FIELD OF INVENTION
[0001] The present subject matter relates to packet fragmentation and,
particularly, but not exclusively, to packet fragmentation in internet protocol
netw5 orks.
BACKGROUND
[0002] Packet-switching networks are networks in which data, before its
transmission over the network, is divided in data packets. The data packets can be
transmitted based on Internet Protocol (IP). Such data packets are referred to as IP
10 packets. Each of the IP packets has a packet header or an IP header, that includes
routing information for the respective IP packet. The routing information provides
indication to follow to the intermediate network nodes, or the routers, between a
source node from where the respective packet is originated and a destination node
to where the respective packet is to be transmitted. Based on the routing
15 information in the packet header, the corresponding IP packet can be transmitted
independently through the routers from the source node to the destination node.
[0003] Further, the intermediate network nodes between the source node and
the destination node in an IP network link may have different outlink maximum
transmission units (MTUs) associated therewith. An outlink MTU for a node
20 governs the maximum size of the IP packet that can be transmitted out from the
node. The outlink MTU for a node may also refer to the maximum capacity of a
communication link from the node to the next node. In order to transmit IP
packets from the source node to the destination node, with varying MTUs at the
intermediate network nodes, the IP packets may have to be fragmented in view of
25 the varying MTUs and then reassembled.
SUMMARY
[0004] This summary is provided to introduce concepts related to packet
fragmentation in internet protocol (IP) networks. This summary is not intended to
3
identify features of the claimed subject matter nor is it directed to use in
determining or limiting the scope of the claimed subject matter.
[0005] In an implementation of the present subject matter, a method for
fragmentation of IP packets for transmission between two terminal nodes in an IP
network is disclosed. The method includes obtaining, at a first terminal 5 node,
outlink maximum transmission units (MTUs) of nodes in a packet transmission
path between the first terminal node and a second terminal node in the IP network.
The nodes comprise intermediate network nodes and at least one of the first
terminal node and the second terminal node. The method also includes
10 determining, at the first terminal node, a permissible outlink payload for each of
the nodes. The permissible outlink payload for the each node is a minimum
outlink MTU from amongst the outlink MTU of the respective node and the
outlink MTUs of nodes prior to the respective node in the packet transmission
path. The method also includes determining, at the first terminal node, an MTU
15 degradation factor for each of the nodes. The MTU degradation factor for the each
node is determined based on a ratio of the permissible outlink payload for the
respective node to the permissible outlink payload for a prior node adjacent to the
respective node in the packet transmission path. The MTU degradation factor for
a node indicates whether the node is a bottleneck for the IP packets in the packet
20 transmission path. The method further includes identifying, at the first terminal
node, a set of fragmentation nodal points for fragmentation of IP packets during
transmission between the first terminal node and the second terminal node. The
set of fragmentation nodal points includes one of the first terminal node and the
second terminal node, and the intermediate network nodes having the MTU
25 degradation factor as one of more than and equal to a predefined threshold MTU
degradation factor.
[0006] In accordance with another implementation of the present subject
matter, a terminal node in an IP network is disclosed. The terminal node includes
a processor and a fragmentation nodes identification module coupled to the
30 processor. The fragmentation nodes identification module may obtain outlink
maximum transmission units (MTUs) of nodes in a packet transmission path
4
between the terminal node and other terminal node in the IP network. The nodes
comprise intermediate network nodes and at least one of the terminal node and the
other terminal node. The fragmentation nodes identification module may also
determine a permissible outlink payload for each of the nodes. The permissible
outlink payload for the each node is a minimum outlink MTU from amongst 5 ngst the
outlink MTU of the respective node and the outlink MTUs of nodes prior to the
respective node in the packet transmission path. The fragmentation nodes
identification module may also determine an MTU degradation factor for each of
the nodes. The MTU degradation factor for the each node is determined based on
10 a ratio of the permissible outlink payload for the respective node to the
permissible outlink payload for a prior node adjacent to the respective node in the
packet transmission path. The MTU degradation factor for a node indicates
whether the node is a bottleneck for the IP packets in the packet transmission
path. The fragmentation nodes identification module may further identify a set of
15 fragmentation nodal points for fragmentation of IP packets during transmission
between the terminal node and the other terminal node. The set of fragmentation
nodal points includes one of the terminal node and the other terminal node, and
the intermediate network nodes having the MTU degradation factor as one of
more than and equal to a predefined threshold MTU degradation factor.
20 [0007] In accordance with another implementation of the present subject
matter, a non-transitory computer readable medium comprising instructions to
implement a method for fragmentation of IP packets for transmission between two
terminal nodes in an IP network is disclosed. The method includes obtaining
outlink maximum transmission units (MTUs) of nodes in a packet transmission
25 path between a first terminal node and a second terminal node in the IP network.
The nodes comprise intermediate network nodes and at least one of the first
terminal node and the second terminal node. The method also includes
determining a permissible outlink payload for each of the nodes. The permissible
outlink payload for the each node is a minimum outlink MTU from amongst the
30 outlink MTU of the respective node and the outlink MTUs of nodes prior to the
respective node in the packet transmission path. The method also includes
5
determining an MTU degradation factor for each of the nodes. The MTU
degradation factor for the each node is determined based on a ratio of the
permissible outlink payload for the respective node to the permissible outlink
payload for a prior node adjacent to the respective node in the packet transmission
path. The MTU degradation factor for a node indicates whether the 5 e node is a
bottleneck for the IP packets in the packet transmission path. The method further
includes identifying a set of fragmentation nodal points for fragmentation of IP
packets during transmission between the first terminal node and the second
terminal node. The set of fragmentation nodal points includes one of the first
10 terminal node and the second terminal node, and the intermediate network nodes
having the MTU degradation factor as one of more than and equal to a predefined
threshold MTU degradation factor.
BRIEF DESCRIPTION OF THE FIGURES
[0008] The detailed description is described with reference to the
15 accompanying figures. In the figures, the left-most digit(s) of a reference number
identifies the figure in which the reference number first appears. The same
numbers are used throughout the figures to reference like features and
components. Some implementations of system and/or methods in accordance with
implementations of the present subject matter are now described, by way of
20 examples, and with reference to the accompanying figures, in which:
[0009] Figure 1 schematically illustrates a network communication link in an
IP network having two terminal nodes and intermediate network nodes, in
accordance with an implementation of the present subject matter.
[0010] Figure 2 illustrates a terminal node of an IP network, according to an
25 implementation of the present subject matter.
[0011] Figure 3 illustrates the flow of request message and response message
between a first terminal node and a second terminal node, in accordance with an
implementation of the present subject matter.
6
[0012] Figure 4 illustrates transmission of an IP packet between the first
terminal node and the second terminal node based on fragmentation nodal points,
in accordance with an implementation of the present subject matter.
[0013] Figure 5 illustrates a comparison of bandwidth utilization for IPv4
framework, for IPv6 framework, and selective fragmentation of the 5 present
subject matter, with respect to an example.
[0014] Figures 6(a) and 6(b) illustrate exemplary methods for fragmentation
of IP packets for transmission between two terminal nodes in an IP network, in
accordance with an implementation of the present subject matter.
10 [0015] It should be appreciated by those skilled in the art that any block
diagrams herein represent conceptual views of illustrative systems embodying the
principles of the present subject matter. Similarly, it will be appreciated that any
flow charts, flow diagrams, state transition diagrams, pseudo code, and the like
represent various processes which may be substantially represented in computer
15 readable medium and so executed by a computer or processor, whether or not
such computer or processor is explicitly shown.
DESCRIPTION OF EMBODIMENTS
[0016] The present subject matter relates to methods and devices for
fragmentation of Internet Protocol (IP) packets for transmission between two
20 terminal nodes in an IP network.
[0017] In an IP network, IP packets are typically transmitted between two
terminal nodes, through intermediate network nodes, based on Internet Protocol
version 4 (IPv4) framework or based on Internet Protocol version 6 (IPv6)
framework. The terminal nodes may be understood as the nodes located at the
25 terminal ends of the network. The terminal node from which the IP packets are
transmitted may be referred to as a source node, and the terminal node to which
the IP packets are transmitted may be referred to as a destination node. The
terminal nodes are generally linked to each other through multiple intermediate
network nodes, such as routers. Each node in the link has an outlink maximum
30 transmission unit (MTU) which is the maximum size of the IP packet that can be
7
transmitted out from the respective node. A node at which an IP packet is
fragmented may be referred to as a fragmentation nodal point.
[0018] In IPv4 framework, routers in the network link are involved in
fragmentation of IP packets. In this, if it is determined at a node that the size of a
packet is more than the outlink MTU of the node, the packet is fragmented in5 to
two or more fragments, such that each fragmented packet is of size less than or
equal to the outlink MTU of the node. IPv4 framework mandates each router in
the network link to fragment the IP packet depending on the associated outlink
MTU. Thus, in the IPv4 based transmission of IP packets, the number of
10 fragmentation nodal points that may exist between the terminal nodes is
substantially large. Also, the fragmentation at each router, depending on its
outlink MTU, adds a processing overhead at the router as new packet headers are
generated and incorporated in the fragmented packets. Further, since the
fragmented packets are not reassembled in the routers, but at the destination node,
15 small sized fragmented packets may be transmitted through high capacity nodes,
i.e., through the nodes with higher outlink MTU. With this, the bandwidth across
the network link may be underutilized which may adversely affect the efficiency
of transmission of IP packets over the network link.
[0019] In IPv6 framework, routers in the network link are not involved in
20 fragmentation of IP packets. The fragmentation of IP packets and the reassembly
of the fragmented packets are done at the terminal nodes, i.e., at the source node
and the destination node, respectively. According to IPv6 framework, the smallest
outlink MTU from amongst the outlink MTUs of the nodes in the network link is
determined. The smallest outlink MTU is also referred to as path MTU across the
25 network link with respect to IPv6 framework. Each IP packet is fragmented at the
source node, such that each fragmented packet is of size less than or equal to this
determined smallest outlink MTU. With this, although the processing overhead,
due to fragmentation at the routers is eliminated, the number of fragmented
packets that are processed and transmitted over the network link is substantially
30 large. With the large number of fragmented packets, the probability or the chances
of packet drops is also large. A large number of packets may thus have to be
8
resent, which may result in poor performance of packet transmission over the
network link. Further, since the fragmentation of IP packets is done at the source
node based on a fixed minimum outlink MTU and the fragmented packets are
reassembled at the destination node, small sized fragmented packets may be
transmitted through the nodes with higher outlink MTU. With this, the band5 width
across the network link may be underutilized which may adversely affect the
efficiency of transmission of IP packets over the network link.
[0020] Further, the use of IPv6 framework may affect the performance and
efficiency of multicasting of IP packets in a multicast network that includes core
10 networks and multiple edge networks. The core networks may not have bandwidth
constraints, but the edge networks generally have bandwidth constraints. Thus, in
a multicast network, if a node, for example, in an edge network has a relatively
smaller outlink MTU with respect to the outlink MTUs of the nodes in the core
networks, then the source nodes in the core networks may have to fragment the IP
15 packets based on that smallest outlink MTU. This may lead to processing of large
number of fragmented packets at each node in the multicast network, with a
higher probability of packet drops or loss. Further, the higher bandwidth sections
within the core network may remain under utilized.
[0021] The present subject matter describes methods and devices for
20 fragmentation of IP packets for transmission in an IP network. The devices,
according to the present subject matter, may be network devices located at the
terminal ends of the IP network and referred to as terminal nodes. Each of the
terminal nodes can function as a source node or a destination node for the IP
packets, depending on the direction of transmission of IP packets between the
25 terminal nodes. Further, the terminal nodes can communicate with each other
through multiple intermediate network nodes, such as routers, for the transmission
of IP packets.
[0022] With the devices and the methods of the present subject matter, the
fragmentation of IP packets follows selective fragmentation, where the IP packets
30 are selectively fragmented at a set of nodes identified for fragmentation. The
nodes for fragmentation, also referred to as fragmentation nodal points, are
9
identified from amongst all the nodes between the two terminal nodes in
accordance with the present subject matter, such that the bandwidth utilization and
the packet transmission throughput across the IP network link is optimum. The
selective fragmentation of the present subject matter is unlike the IPv4 framework
which mandates fragmentation at each router on a need basis, depending 5 g on the
associated outlink MTU and also unlike the IPv6 framework in which
fragmentation is done at a terminal node and not at the routers in the network link.
Thus, in accordance with the present subject matter, the number of fragmentation
nodal points over the IP network link may be smaller in comparison to that in the
10 case of IPv4 framework and the number of fragmented packets transmitted over
the IP network link may not be large in comparison to that in the case of IPv6
framework. With this, the processing overhead on the routers in the IP network
link is also substantially reduced and a relatively smaller probability of packet
drops or loss can be substantially ensured.
15 [0023] In accordance with the methodology of the present subject matter,
outlink MTUs of nodes in a packet transmission path between the two terminal
nodes in the IP network are obtained. The two terminal nodes may be referred to
as a first terminal node and a second terminal node. The packet transmission may
be understood as a route for transmission of IP packets between the two terminal
20 nodes. The nodes in the packet transmission path may include the intermediate
network nodes, for example the routers, between the two terminal nodes, and
include one of the terminal nodes whichever is indicative of a source node for
transmission of IP packets.
[0024] In an implementation, the outlink MTUs may be obtained for the nodes
25 in a packet transmission path in a direction from the first terminal node (source
node) to the second terminal node (destination node). For such a case, the nodes
for which the outlink MTUs are obtained include the first terminal node. In an
implementation, the outlink MTUs may be obtained for the nodes in a packet
transmission path in a direction from the second terminal node (source node) to
30 the first terminal node (destination node). For such a case, the nodes for which the
outlink MTUs are obtained include the second terminal node.
10
[0025] After obtaining the outlink MTUs of the nodes, a permissible outlink
payload is determined for each of the nodes. The permissible outlink payload for
each node is a minimum outlink MTU from amongst the outlink MTU of the
respective node and the outlink MTUs of nodes prior to the respective node in the
packet transmission path. In other words, the permissible outlink payload 5 oad for a
node is a minimum outlink MTU from amongst the outlink MTUs of the nodes
from the source node to that node. The permissible outlink payload for a node is
indicative of the maximum size of IP packet that may be transmitted out from the
node, in view of the outlink MTUs of the nodes prior to that node.
10 [0026] Further, after determining the permissible outlink payloads for the
nodes, an MTU degradation factor is determined for each of the nodes. The MTU
degradation factor for each node is determined based on a ratio of the permissible
outlink payload for the respective node to the permissible outlink payload for a
prior node adjacent to the respective node in the packet transmission path. In an
15 implementation, the MTU degradation factor for a node is determined based on
one minus the ratio of the permissible outlink payloads as mentioned above.
[0027] The MTU degradation factor for a node is indicative of by how much
the outlink MTU of the node has reduced with respect to the prior adjacent node.
The MTU degradation factor for a node indicates the extent to which the node is a
20 bottleneck for the IP packets to be fragmented at the node. The larger the value of
MTU degradation factor for a node the larger is the degree of bottleneck posed by
the node in terms of payload carrying capacity from the node.
[0028] After determining the MTU degradation factor for the nodes, a set of
fragmentation nodal points are identified. The set of fragmentation nodal points
25 includes nodes, from amongst the nodes in the packet transmission path between
the terminal nodes, at which IP packets may be fragmented during the
transmission. The set of fragmentation nodal points includes the first terminal
node or the second terminal node, whichever acts as a source node for
transmission of IP packets. The set of fragmentation nodal points also includes the
30 routers for which the MTU degradation factor is more than or equal to a
predefined threshold MTU degradation factor. The predefined threshold MTU
11
degradation factor may be a reference for identification or selection of a node in
the set of fragmentation nodal points. The nodes for which the MTU degradation
factor is less than the predefined threshold MTU degradation factor may pose
relatively smaller bottleneck for the IP packets, and the nodes for which the MTU
degradation factor is more than or equal to the predefined threshold 5 old MTU
degradation factor may pose relatively large bottleneck for the IP packets. Further,
the nodes for which the MTU degradation factor is zero may not pose any
bottleneck for the IP packets. The set of fragmentation nodal points, as mentioned
above, may be an initial set of fragmentation nodal points. This initial set of
10 fragmentation nodal points may be normalized to determine a final set of
fragmentation nodal points that may be considered for the packet fragmentation
and transmission.
[0029] In an implementation, the initial set of fragmentation nodal points may
be normalized based on one or more normalization conditions. The normalization
15 is performed to optimize the number of fragmentation nodal points at which the IP
packets may be fragmented during the transmission. In an example, a
normalization condition may convey that when the set of fragmentation nodal
points includes consecutive intermediate network nodes, one of the consecutive
intermediate network nodes that is closer to a destination node in the packet
20 transmission path is retained and other nodes of the consecutive intermediate
network nodes are dropped from the set of fragmentation nodal points.
[0030] In an example, a normalization condition may convey that when the set
of fragmentation nodal points has two vicinity intermediate network nodes
separated by at most a predefined number of intermediate network nodes, then
25 one of the two vicinity intermediate network nodes that is closer to the destination
node in the packet transmission path is retained and other of the two vicinity
intermediate network nodes is dropped from the set of fragmentation nodal points.
The predefined number of intermediate network nodes, for example, may be one.
[0031] In an example, a normalization condition may convey that when a
30 number of fragmentation nodal points is more than a predefined permissible
number of fragmentation nodal points, then the intermediate network nodes with
12
least MTU degradation factors are dropped till the number of fragmentation nodal
points is equal to the predefined permissible number of fragmentation nodal
points. The predefined permissible number of fragmentation nodal points, for
example, may be equal to half of the total number of nodes in the packet
transmission 5 path.
[0032] After identifying and normalizing the fragmentation nodal points, a
revised permissible outlink MTU (RP-MTU) is determined for each of the
fragmentation nodal points. The RP-MTU of a fragmentation nodal point
indicates the maximum size of the IP packet that can be transmitted out from the
10 fragmentation nodal point, without the IP packet being fragmented further in the
packet transmission path till the next fragmentation nodal point. The RP-MTU of
a fragmentation nodal point can be referred to as the path MTU for the packet
transmission path from that fragmentation nodal point to the next fragmentation
nodal point from the set. In an implementation, the RP-MTU for each
15 fragmentation nodal point, except the last fragmentation nodal point, is the
permissible outlink payload of a node prior to a subsequent fragmentation nodal
point. Further, the RP-MTU for the last fragmentation nodal point is the
permissible outlink payload of last intermediate network node prior to the
destination node in the packet transmission path.
20 [0033] In an implementation, the set of fragmentation nodal points and the
RP-MTUs for the fragmentation nodal points in the set may be determined
individually for the packet transmission path in the direction from the first
terminal node to the second terminal node and for the packet transmission path in
the direction from the second terminal node to the first terminal node.
25 [0034] In an implementation, the information of the fragmentation nodal
points and the corresponding RP-MTUs may be available at the terminal node
before the IP packets are transmitted out from that terminal node to the other
terminal node. During packet transmission sessions, the terminal node may utilize
the information of the set of fragmentation nodal points and the corresponding
30 RP-MTUs for fragmentation and transmission of IP packets to the other terminal
node.
13
[0035] According to the methodology of the present subject matter, groups of
consecutive nodes with high bandwidths, which lie closer to the source node in
the packet transmission path, are determined, and fragmentation nodal points
which pose a substantially larger degree of bottlenecks in between the identified
groups are selectively identified. This facilitates in optimizing the number o5 f
fragmentation nodal points in the packet transmission path between the terminal
nodes and in utilization of high bandwidth capabilities of the nodes, based on the
identified groups, in the packet transmission path. The methodology of the present
subject matter may also enable in increasing the performance and efficiency of
10 multicast networks, where high bandwidth core networks interface with low
bandwidth edge networks.
[0036] The above methods and devices are further described in conjunction
with the following figures. It should be noted that the description and figures
merely illustrate the principles of the present subject matter. It will thus be
15 appreciated that those skilled in the art will be able to devise various arrangements
that, although not explicitly described or shown herein, embody the principles of
the present subject matter. Furthermore, all examples recited herein are principally
intended to aid the reader in understanding the principles of the present subject
matter. Moreover, all statements herein reciting principles, aspects, and
20 implementations of the present subject matter, as well as specific examples
thereof, are intended to encompass equivalents thereof.
[0037] The methods and devices for fragmentation of IP packets for
transmission in an IP network shall be explained in details with respect to Figures
1 to 6(b). While aspects of described methods and devices for fragmentation of IP
25 packets for transmission in an IP network can be implemented in any number of
different computing devices, network environments, and/or configurations, the
implementations are described in the context of the following exemplary
device(s).
[0038] Figure 1 schematically illustrates a network communication link 100 in
30 an IP network having two terminal nodes 102-1, 102-2 and multiple intermediate
network nodes 104-1, 104-2, … , 104-N, in accordance with an implementation of
14
the present subject matter. The network communication link 100 is also referred
to as an IP network link. The two terminal nodes, namely a first terminal node
102-1 and second terminal node 102-2, may be network devices located at the
terminal ends of the IP network. The terminal nodes 102-1, 102-2 may include,
but are not restricted to, personal computers, tablets, smartphones, servers, an5 d
such. The intermediate network nodes 104-1, 104-2, … , 104-N may include
network devices, such as routers. The intermediate network nodes 104-1, 104-2,
… , 104-N hereinafter are collectively referred to as intermediate network nodes
104 and individually referred to as an intermediate network node 104. For the
10 purposes of description herein, the intermediate network node(s) 104 are
interchangeably referred to router(s) 104.
[0039] As shown in Figure 1, the first terminal node 102-1 includes a
fragmentation nodes identification module 106 which is configured to identify a
set of fragmentation nodal points, in accordance with the present subject matter,
15 for the purposes of fragmentation of IP packets during transmission between the
terminal nodes 102-1, 102-2. The first terminal node 102-1, as shown, also
includes outlink MTU data 108, permissible payload data 110, and degradation
factor data 112 that respectively store outlink MTUs, permissible outlink
payloads, and MTU degradation factors associated with nodes in the network
20 communication link 100. The fragmentation nodes identification module 106
obtains or determines the outlink MTUs, the permissible outlink payloads, and the
MTU degradation factors for the nodes, and then identifies the set of
fragmentation nodal points based on the obtained or determined parameters for
the nodes. The details of identification of the set of fragmentation nodal points are
25 described later with reference to the description of Figure 2.
[0040] For the sake of simplicity, Figure 1 shows that the first terminal node
102-1 includes the fragmentation nodes identification module 106, the outlink
MTU data 108, the permissible payload data 110, and the degradation factor data
112. However, in various implementations, the fragmentation nodes identification
30 module 106, the outlink MTU data 108, the permissible payload data 110, and the
15
degradation factor data 112 may be included in the second terminal node 102-2, or
in both the first terminal node 102-1 and the second terminal node 102-2.
[0041] Figure 2 illustrates a terminal node 102 of an IP network, according to
an implementation of the present subject matter. The terminal node 102 can be the
first terminal node 102-1 or the second terminal node 102-2. It may be understoo5 d
that, in an implementation, both the terminal nodes 102-1 and 102-2 may have
similar components as shown in Figure 2.
[0042] In an implementation, the terminal node 102 includes processor(s) 202,
I/O interface(s) 204, and a memory 206 coupled to the processor(s) 202. The
10 processor(s) 202 may be implemented as one or more microprocessors,
microcomputers, microcontrollers, digital signal processors, central processing
units, state machines, logic circuitries, and/or any devices that manipulate signals
based on operational instructions. Among other capabilities, the processor(s) 202
are configured to fetch and execute computer-readable instructions stored in the
15 memory 206.
[0043] The functions of the various elements shown in the figure, including
any functional blocks labeled as “processor(s)”, may be provided through the use
of dedicated hardware as well as hardware capable of executing computerreadable
instructions. When provided by a processor, the functions may be
20 provided by a single dedicated processor, by a single shared processor, or by a
plurality of individual processors, some of which may be shared. Moreover,
explicit use of the term “processor” should not be construed to refer exclusively to
hardware capable of executing software, and may implicitly include, without
limitation, digital signal processor (DSP) hardware, network processor,
25 application specific integrated circuit (ASIC), field programmable gate array
(FPGA), read only memory (ROM) for storing software, random access memory
(RAM), and non volatile storage. Other hardware, conventional and/or
customized, may also be included.
[0044] The I/O interface(s) 204 may include a variety of software and
30 hardware interfaces, for example, interfaces for peripheral device(s), such as data
input output devices, referred to as I/O devices, storage devices, network devices,
16
etc. The I/O device(s) may include Universal Serial Bus (USB) ports, Ethernet
ports, host bus adaptors, etc., and their corresponding device drivers. The I/O
interface(s) 204 facilitate the communication of the terminal node 102 with
various network devices, such as routers 104, and communication devices, such as
servers, computers, tablets, and sm5 artphones.
[0045] The memory 206 may include any computer-readable medium
including volatile memory, such as Static Random Access Memory (SRAM) and
Dynamic Random Access Memory (DRAM), and/or non-volatile memory, such
as read only memory (ROM), erasable programmable ROM, flash memories, hard
10 disks, optical disks, and magnetic tapes.
[0046] The terminal node 102 may also include module(s) 208 and data 210.
The module(s) 208, amongst other things, are coupled to, and executable by, the
processor(s) 202. The module(s) 208 include routines, programs, objects,
components, data structures, etc., which perform particular tasks or implement
15 particular abstract data types. The module(s) 208 may also be implemented as,
signal processor(s), state machine(s), logic circuitries, and/or any other device or
component that manipulate signals based on operational instructions.
[0047] Further, the module(s) 208 can be implemented in hardware,
instructions executed by a processing unit, or by a combination thereof. The
20 processing unit can comprise a computer, a processor, such as the processor 202, a
state machine, a logic array or any other suitable devices capable of processing
instructions. The processing unit can be a general-purpose processor which
executes instructions to cause the general-purpose processor to perform the tasks,
or the processing unit can be dedicated to perform the functions, in accordance
25 with the present subject matter.
[0048] In another aspect of the present subject matter, the module(s) 208 may
be machine-readable instructions which, when executed by a processor/processing
unit, perform any of the described functionalities. The machine-readable
instructions may be stored on an electronic memory device, hard disk, optical disk
30 or other machine-readable storage medium or non-transitory medium. In one
17
implementation, the machine-readable instructions can be also be downloaded to
the storage medium via a network connection.
[0049] In an implementation, the module(s) 208 includes the fragmentation
nodes identification module 106, a packet processing module 212, and other
module(s) 214. The other module(s) 214 may include programs or code5 d
instructions that supplement applications and functions of the terminal node 102.
The data 210 amongst other things, serves as a repository for storing data
processed, received, associated, and generated by one or more of the module(s)
208. The data 210 includes, for example, nodes data 216 that stores the outlink
10 MTU data 108, the permissible payload data 110, and the degradation factor data
112. The data 210 may also include fragmentation nodal points data 218 that
stores node identifier data 220 and RP-MTU data 222. The data 210 may further
include other data 224 that stores data generated as a result of the execution of one
or more modules in the other module(s) 214. Although the data 210 is shown
15 internal to the terminal node 102, it may be understood that the data 210 can
reside in an external memory which is coupled to the processor(s) 202 of the
terminal node 102.
[0050] The description hereinafter describes the procedure of identifying the
set of fragmentation nodal points in the network communication link 100 and then
20 utilizing the information associated with the set of fragmentation nodal points for
fragmentation and transmission of IP packets between the two terminal nodes
102-1 and 102-2 in the network communication link 100. As an example, the
description herein describes the procedure of identifying the set of fragmentation
nodal points at the first terminal node 102-1, which functions as a source node for
25 the IP packets transmitted to the second terminal node 102-2 and functions as a
destination node for the IP packets transmitted from the second terminal node
102-2. Separate sets of fragmentation nodal points may be identified at the first
terminal node 102-1, one for the fragmentation and the transmission of IP packets
in a direction from the first terminal node 102-1 to the second terminal node 102-
30 2, and the other for the fragmentation and the transmission of IP packets in a
direction from the second terminal node 102-2 to the first terminal node 102-1. It
18
may be understood that the procedure can be performed in a similar manner in the
second terminal node 102-2.
[0051] Further, in an implementation, the procedure may be performed at the
terminal node 102 in two phases: (1) pre-packet transmission session phase; and
(2) packet transmission session phase. In the pre-packet transmission 5 session
phase the terminal node 102 identifies the set of fragmentation nodal points, and
in the packet transmission session phase the terminal node 102 utilizes the
information associated with the set of fragmentation nodal points for the
fragmentation and the transmission of IP packets.
10 [0052] Further, the procedure described herein is with reference to an example
where the network communication link 100 between the first terminal node 102-1
and the second terminal node 102-2 includes ten routers 104, referenced by R1,
R2, … , R10. The first terminal node 102-1 and the second terminal node 102-2
are referenced by T1 and T2. The example considered here is for the purposes of
15 the explaining the procedure; however, the same procedure can be performed for
the network communication link 100 having N number of routers 104.
Pre-Packet Transmission Session Phase
[0053] For the purpose of identifying the set of fragmentation nodal points,
the fragmentation nodes identification module 106 obtains outlink MTUs and
20 node identifiers of the nodes in a packet transmission path in a direction from the
first terminal node 102-1 to the second terminal node 102-2. The nodes for which
the outlink MTUs and the node identifiers are obtained include the first terminal
node 102-1 and the routers 104 from R1 to R10.
[0054] In an implementation, for obtaining the outlink MTUs, the
25 fragmentation nodes identification module 106 may send an Internet Control
Message Protocol (ICMP) based request message to the second terminal node
102-2 through the routers 104, where the ICMP based request message has a type
value of one of 41 to 255. Such a type value is configured in the ICMP based
request message to indicate to include, at each of the nodes, the outlink MTU and
30 a node identifier of the respective node in the ICMP based request message. The
19
node identifier of a node is code that uniquely identifies the node. With this, when
the ICMP based request message reaches a node, for example, router R4, the
router R4 checks for the type value in the ICMP based request message. If the
type value is one of 41 to 255, as the case maybe, the outlink MTU and the node
identifier of the router R4 are included in the ICMP based request message an5 d
forwarded to the next node, i.e., router R5. The same procedure is performed at
each of the nodes till the second terminal node 102-2. Thus, the ICMP based
request message at the second terminal node 102-2 includes the outlink MTUs and
the node identifiers of the nodes that are in the packet transmission path from the
10 first terminal node 102-1 to the second terminal node 102-2. In an
implementation, a node, i.e., a router 104, may not add its node identifier and the
outlink MTU in the ICMP based request message, even if the type value is one of
41 to 255, and thus may not be considered for identification of fragmentation
nodal points.
15 [0055] After this, in response to the ICMP based request message, the second
terminal node 102-2 may send an ICMP based response message to the first
terminal node 102-1, where the ICMP based response message includes the
outlink MTUs and the node identifiers of the nodes as included in the ICMP based
request message. The fragmentation nodes identification module 106 in the first
20 terminal node 102-1 may receive the ICMP response message to obtain the node
identifiers and the outlink MTUs. The node identifiers and the outlink MTUs of
the nodes may be stored in the outlink MTU data 108.
[0056] Table 1 illustrates examples of node identifiers and outlink MTUs of
the nodes that may be included in the ICMP based request message at the second
25 terminal node 102-2 and obtained at the first terminal node 102-1 through the
ICMP based response message. IDT1 refers to the node identifier for the first
terminal node T1, and IDR1 to IDR10 refer to the node identifiers for the router
nodes R1 to R10. The values of the outlink MTUs are example values for the
purposes of explanation herein. Other values are also possible.
30 Table 1
Node Identifier Outlink MTU (bytes)
20
IDT1 9000
IDR1 8000
IDR2 6000
IDR3 5500
IDR4 3000
IDR5 1400
IDR6 1450
IDR7 1480
IDR8 1500
IDR9 1470
IDR10 576
[0057] After obtaining the node identifiers and the outlink MTUs of the
nodes, the fragmentation nodes identification module 106 determines a
permissible outlink payload and an MTU degradation factor for each of the nodes.
The permissible outlink payload for a node is a minimum outlink MTU 5 from
amongst the outlink MTUs of the nodes from the first terminal node 102-1 to that
node. The permissible outlink payload for a node Rn, in the direction from the
first terminal node 102-1 T1 to the second terminal node 102-2 T2, can be
determined by Equation 1.
10 POPRn (T1 → T2) = min (MTUT1, MTUR1, … , MTURn) , … (1)
where POP denotes the permissible outlink payload and MTU denotes the outlink
MTU.
[0058] The MTU degradation factor for a node is determined as one minus the
ratio of the permissible outlink payload for that node to the permissible outlink
15 payload for a prior node adjacent to that node. In an implementation, the value of
one minus the ratio may be multiplied by 100 to determine the MTU degradation
factor for the node in percentage. The MTU degradation factor for a node Rn, in
the direction from the first terminal node 102-1 T1 to the second terminal node
102-2 T2, can be determined by Equation 2.
21
MTU-DFRn (T1 → T2) = [1 – (POPRn/POPRn-1)] x 100 % , … (2)
where MTU-DF denotes the MTU degradation factor.
[0059] The permissible outlink payloads and the MTU degradation factors for
the nodes are stored in the permissible payload data 110 and the degradation
factor data 112, respectively5 .
[0060] After this, the fragmentation nodes identification module 106
compares the MTU degradation factor of each of the nodes with a predefined
threshold MTU degradation factor to identify a set of fragmentation nodal points.
In an implementation, the nodes for which the MTU degradation factor is more
10 than or equal to the predefined threshold MTU degradation factor are identified in
the set. This identified set of fragmentation nodal points may be an initial set of
fragmentation nodal points, before performing the normalization based on one or
more normalization conditions, as described later in the description.
[0061] Table 2 illustrates examples of permissible outlink payloads and MTU
15 degradation factors of the nodes with reference to the example values of outlink
MTUs of the nodes as illustrated in Table 1. Based on the above description for
permissible outlink payload, the permissible outlink payload for router R1 is 8000
bytes, which is the minimum outlink MTU from amongst the outlink MTUs of T1
to R1. Similarly, the permissible outlink payload for router R4 is 3000 bytes,
20 which is the minimum outlink MTU from amongst the outlink MTUs of T1 to R4.
Similarly, the permissible outlink payload for router R8 is 1400 bytes, which is
the minimum outlink MTU from amongst the outlink MTUs of T1 to R8. Further,
based on the description for MTU degradation factor, the MTU degradation factor
for router R1 is 11.11 %, which is based on (1 – (8000/9000)) x 100 %. Similarly,
25 the MTU degradation factor for router R4 is 45.45 %, which is based on (1 –
(3000/5500)) x 100 %. Similarly, the MTU degradation factor for router R8 is 0
%, which is based on (1 – (1400/1400)) x 100 %. It may be noted that the MTU
degradation factor for the first terminal node 102 T1 is not computed as there is
no node prior to T1.
30 Table 2
22
Node
Identifier
Outlink
MTU (bytes)
Permissible
Outlink
Payload (bytes)
MTU
degradation
factor (%)
Flag
IDT1 9000 9000 - 1
IDR1 8000 8000 11.11 % 0
IDR2 6000 6000 25 % 0
IDR3 5500 5500 8.33 % 0
IDR4 3000 3000 45.45 % 1
IDR5 1400 1400 53.33 % 1
IDR6 1450 1400 0 % 0
IDR7 1480 1400 0 % 0
IDR8 1500 1400 0 % 0
IDR9 1470 1400 0 % 0
IDR10 576 576 58.86 % 1
[0062] Further, considering that the predefined threshold MTU degradation
factor is 40 %, routers R3, R4, and R10 are determined to be fragmentation nodal
points in the initial set. It may be noted that the initial set includes, by default, the
first terminal node 102 T1, as the source node has to be a fragmentation 5 nodal
point. In an implementation, a flag is set for the nodes that are identified in the set
of fragmentation nodal points based on the respective MTU degradation factors.
As illustrated in Table 2, the flags for the first terminal node 102 T1, and the
routers R4, R5, and R10 are set.
10 [0063] After identifying the initial set of fragmentation nodal points, in an
implementation, the fragmentation nodes identification module 106 may
normalize the initial set of fragmentation nodal points based on one or more
normalization conditions. In an example, the fragmentation nodes identification
module 106 may scan the flag of each node to determine whether the respective
15 node is in the initial set of fragmentation nodal points, for the purpose of
normalization.
23
[0064] In an example, a first normalization condition may convey that when
the set of fragmentation nodal points includes consecutive intermediate network
nodes, one of the consecutive intermediate network nodes that is closer to a
destination node in the packet transmission path is retained and other nodes of the
consecutive intermediate network nodes are dropped from the set of fragmentatio5 n
nodal points. In an example, a second normalization condition may convey that
when the set of fragmentation nodal points has two vicinity intermediate network
nodes separated by at most a predefined number of intermediate network nodes,
then one of the two vicinity intermediate network nodes that is closer to the
10 destination node in the packet transmission path is retained and other of the two
vicinity intermediate network nodes are dropped from the set of fragmentation
nodal points. The predefined number of intermediate network nodes, for example,
may be one, two, or more. In an example, a third normalization condition may
convey that when a number of fragmentation nodal points is more than a
15 predefined permissible number of fragmentation nodal points, then the
intermediate network nodes with least MTU degradation factors are dropped till
the number of fragmentation nodal points is equal to the predefined permissible
number of fragmentation nodal points. The predefined permissible number of
fragmentation nodal points, for example, may be equal to half of the total number
20 of nodes in the packet transmission path.
[0065] In an implementation, the fragmentation nodes identification module
106 may apply the above normalization conditions in the order of the first
normalization condition then the second normalization condition and then the
third normalization, for normalizing the initial set of fragmentation nodal points.
25 [0066] With reference to the example illustrated through Table 2, the
fragmentation nodes identification module 106 may normalize the initial set of
fragmentation nodal points including T1, R4, R5, and R10, for which the flag is
set. Based on the first normalization condition, the fragmentation nodes
identification module 106 may determine R4 and R5 as two consecutive nodes
30 and thus retain R5 and drop R4 from the set of fragmentation nodal points, as R5
24
is closer to the second terminal node 102-2 (destination node in the direction from
T1 to T2).
[0067] Further, considering that the predefined number of intermediate
network nodes is one, the second normalization condition may not apply for the
example described herein, as there may not be any vicinity nodes identified 5 d by the
fragmentation nodes identification module 106. Further, the third normalization
condition may also not apply for the example described herein, as the number of
fragmentation nodal points in the set is less than half of the total number of nodes
in the network communication link 100.
10 [0068] Table 3 illustrates the set of fragmentation nodal points that are
identified after the normalization with reference to the example illustrated in
Table 2. As illustrated, the first terminal node 102 T1, and the routers R5 and R10
are identified as the fragmentation nodal points in the set. The node identifiers of
the fragmentation nodal points in the normalized set may be stored in the node
15 identifier data 220.
Table 3
Node
Identifier
Outlink
MTU (bytes)
Permissible
Outlink
Payload (bytes)
MTU
degradation
factor (%)
Flag
IDT1 9000 9000 - 1
IDR5 1400 1400 53.33 % 1
IDR10 576 576 58.86 % 1
[0069] After identifying the normalized set of fragmentation nodal points, the
fragmentation nodes identification module 106 determines a RP-MTU for each of
20 the fragmentation nodal points in the set. In an implementation, the fragmentation
nodes identification module 106 determines the RP-MTU for each fragmentation
nodal point, except the last fragmentation nodal point, as equal to the permissible
outlink payload of the node prior to the next fragmentation nodal point from the
respective fragmentation nodal point. Further, the fragmentation nodes
25 identification module 106 determines the RP-MTU for the last fragmentation
25
nodal point equal to the permissible outlink payload of last intermediate network
node prior to the destination node in the packet transmission path.
[0070] Table 4 illustrates examples of RP-MTUs for the fragmentation nodal
points in the set, with reference to the example illustrated through Table 2 and
Table 3. Based on the above description of the RP-MTU for fragmentation 5 nodal
points, the RP-MTU for the first fragmentation nodal point T1 is 3000 bytes,
which is the permissible outlink payload of R4, as R4 is the node prior to the
subsequent fragmentation nodal point R5. Similarly, the RP-MTU for the second
fragmentation nodal point R5 is 1400 bytes which is the permissible outlink
10 payload of R9, as R9 is the node prior to the subsequent fragmentation nodal point
R10. Further, the RP-MTU for the last fragmentation nodal point R10 is 576 bytes
which is the permissible outlink payload of R10, as R10 is the last router node
prior to the second terminal node 102-2 (the destination node in the direction from
T1 to T2). It may be noted that the MTUs for the nodes in between any two
15 fragmentation nodal points may be same as the RP-MTU of the earlier of the two
fragmentation nodal points. The RP-MTUs of the fragmentation nodal points in
the normalized set may be stored in the RP-MTU data 222.
Table 4
Node
Identifier
Outlink
MTU
(bytes)
Permissible
Outlink Payload
(bytes)
MTU
degradation
factor (%)
Flag RP-MTU
(bytes)
IDT1 9000 9000 - 1 3000
IDR5 1400 1400 53.33 % 1 1400
IDR10 576 576 58.86 % 1 576
20 [0071] It may be noted that the set of fragmentation nodal points, as described
above, is for the fragmentation and the transmission of IP packets in the direction
from the first terminal node 102-1 to the second terminal node 102-2. The
description below describes the procedure of identifying, at the first terminal node
102-1, a set of fragmentation nodal points for the fragmentation and the
26
transmission of IP packets in the direction from the second terminal node 102-2 to
the first terminal node 102-1.
[0072] For this, the fragmentation nodes identification module 106 of the first
terminal node 102-1 obtains the node identifiers and the outlink MTUs of the
nodes in a packet transmission path in the direction from the second terminal 5 inal node
102-2 to the first terminal node 102-1. The nodes herein include the second
terminal node 102-2 and the routers 104 from R10 to R1. In an implementation,
the node identifiers and the outlink MTUs of the nodes for this direction may be
obtained in the ICMP based response message which is received at the first
10 terminal node 102-1 from the second terminal node 102-2, as mentioned earlier.
In an implementation, the ICMP based response message is sent from the second
terminal node 102-2 to the first terminal node 102-1 through the routers 104,
where the ICMP based response message has a type value of one of 41 to 255.
Such a type value is configured in the ICMP based response message to indicate
15 to include, at each of the nodes, the outlink MTU and the node identifier of the
respective node in the ICMP based response message, in a similar manner as done
for the ICMP based request message, as describe earlier. Thus, the ICMP based
response message at the first terminal node 102-1 includes the outlink MTUs and
the node identifiers of the nodes that are in the packet transmission path from the
20 second terminal node 102-2 to the first terminal node 102-1. It may be understood
that this information in the ICMP based response message may be in addition to
the information of the nodes in the direction from the first terminal node 102-1 to
the second terminal node 102-2, as described earlier. The node identifiers and the
outlink MTUs of the nodes in the direction from the second terminal node 102-2
25 to the first terminal node 102-1 may be stored in the outlink MTU data 108.
[0073] Table 5 illustrates examples of node identifiers and outlink MTUs of
the nodes that may be included in the ICMP based response message and obtained
at the first terminal node 102-1. IDT2 refers to the node identifier for the second
terminal node T2 and IDR1 to IDR10 refer to the node identifiers for the router
30 nodes R1 to R10. The values of the outlink MTUs are example values for the
purposes of explanation herein. Other values are also possible.
27
Table 5
Node Identifier Outlink MTU (bytes)
IDT2 4000
IDR10 3500
IDR9 3800
IDR8 2000
IDR7 1500
IDR6 1400
IDR5 1200
IDR4 800
IDR3 900
IDR2 850
IDR1 576
[0074] After obtaining the node identifiers and the outlink MTUs of the nodes
in accordance with Table 5, the fragmentation nodes identification module 106
may identify the set of fragmentation nodal points for the direction from 5 the
second terminal node 102-2 to the first terminal node 102-1 in the same manner as
described earlier for the direction from the first terminal node 102-1 to the second
terminal node 102-2. The permissible outlink payload for a node Rn, in the
direction from the second terminal node 102-2 T2 to the first terminal node 102-1
10 T1, can be determined by Equation 3. The MTU degradation factor for a node Rn,
in the direction from the second terminal node 102-2 T2 to the first terminal node
102-1 T1, can be determined by Equation 4.
POPRn (T2 → T1) = min (MTUT2, MTUR10, … , MTURn) , … (3)
where POP denotes the permissible outlink payload and MTU denotes the outlink
15 MTU.
MTU-DFRn (T2 → T1) = [1 – (POPRn/POPRn+1)] x 100 % , … (4)
where MTU-DF denotes the MTU degradation factor.
28
Packet Transmission Session Phase
[0075] For the purpose of transmitting the IP packets from the first terminal
node 102-1 to the second terminal node 102-2, the packet processing module 212
processes each of the IP packets to compare the payload size of the each IP packet
with the minimum RP-MTU from amongst the RP-MTUs for the fragmentatio5 n
nodal points in the set for the direction from the first terminal node 102-1 to the
second terminal node 102-2. With reference to the example illustrated above
through Table 4, the minimum RP-MTU is 576 bytes associated with R10. When
the payload size of an IP packet is more than the minimum RP-MTU, the packet
10 processing module 212 unsets the do-not-fragment bit in a packet header of the IP
packet. When the payload size of an IP packet is less than or equal to the
minimum RP-MTU, the packet processing module 212 sets the do-not-fragment
bit in a packet header of the IP packet. The status of the do-not-fragment bit in a
packet header is indicative of whether the packet may be fragmented at any node
15 in the packet transmission path from the first terminal node 102-1 to the second
terminal node 102-2. The setting of the do-not-fragment bit may indicate
transmission without fragmentation, and the unsetting of the do-not-fragment bit
may indicate transmission with a possible fragmentation.
[0076] In an implementation, if the do-not-fragment bit in the packet header
20 of an IP packet is unset, the packet processing module 212 adds the node
identifiers and the RP-MTUs associated with the fragmentation nodal points in the
packet header of each of the IP packets, so that the IP packets can be fragmented
at each fragmentation nodal point in accordance with the corresponding RP-MTU.
[0077] For example, after processing the IP packets to set or unset the do-not25
fragment bit and accordingly including the information associated with the set of
fragmentation nodal points in the packet headers of the IP packets, at the first
terminal node 102-1 if the payload size of the IP packet is less than or equal to the
minimum RP-MTU, then the IP packet is transmitted to the next node, i.e., router
R1 without any fragmentation. Else, if the payload size of the IP packet is more
30 than the minimum RP-MTU, then the payload size of the IP packet is compared
with the RP-MTU for the first terminal node 102-1. If the payload size of the IP
29
packet is less than or equal to the RP-MTU, then the IP packet is transmitted to
router R1 without fragmentation, and if the payload size is more than the RPMTU,
then the IP packet is fragmented according to the RP-MTU. It may be
noted that the information associated with the do-not-fragment bit and the set of
fragmentation nodal points is included in the packet headers of the fragmented 5 nted IP
packets for assessment at subsequent nodes in the packet transmission path.
[0078] Further, at each of the routers 104 in the packet transmission path the
do-not-fragment bit of each IP packet, received at the respective router 104, is
checked. If the do-not-fragment bit is set in an IP packet, then the IP packet is
10 transmitted to the next node without any fragmentation. Else, if the do-notfragment
bit is unset, then the packet header of the IP packet is scanned to check
whether the respective router 104 is a fragmentation nodal point. If the respective
router 104 is a fragmentation nodal point, the RP-MTU associated with the
respective router 104 is derived from the packet header. Subsequently, the
15 payload size of the IP packet is compared with the RP-MTU for the respective
router 104. If the payload size of the IP packet is less than or equal to the RPMTU,
then the IP packet is transmitted without fragmentation, and if the payload
size is more than the RP-MTU, then the IP packet is fragmented according to the
RP-MTU.
20 [0079] Further, in an implementation, if a router 104 is a fragmentation nodal
point, then, at the router 104, the RP-MTU for the router 104 is compared with the
outlink MTU of the router 104. If the outlink MTU of the router 104 is less than
its RP-MTU, then IP packets may be fragmented and transmitted based on default
framework, i.e., one of the IPv4 or IPv6 frameworks. In an example, if the IPv6
25 framework is the default framework for the IP network, then an error message is
sent to the source node, which may indicate to the failure of transmission of IP
packets. In an example, if the IPv4 framework is the default framework for the IP
network, then the IP packet may be fragmented based on the outlink MTU of the
router 104.
30 [0080] Further, in order to enable the fragmentation and transmission of IP
packets during the transmission from the second terminal node 102-2 to the first
30
terminal node 102-1, the information associated with the set of fragmentation
nodal points for the direction from the second terminal node 102-2 to the first
terminal node 102-1 may have to be provided to the second terminal node 102-2.
For this, in an implementation, the packet processing module 212 of the first
terminal node 102-1 adds the node identifiers and the RP-MTUs 5 s associated with
the set of fragmentation nodal points, for said direction, in the packet header of
each of the IP packets, so that the IP packets can be fragmented at each
fragmentation nodal point in accordance with the corresponding RP-MTU, during
the transmission from the second terminal node 102-2 to the first terminal node
10 102-1.
[0081] Figure 3 illustrates the flow of request message and response message
between a first terminal node T1 and a second terminal node T2, in accordance
with an implementation of the present subject matter. In an example, the request
message and the response message may be an ICMP based request message and
15 an ICMP based response message, as mentioned earlier in the description. In
Figure 3, the examples values of node identifiers and outlink MTUs are with
reference to the values in Table 1 and Table 5. As illustrated in Figure 3, the
arrows in the direction from the first terminal node T1 to the second terminal node
T2 are indicative of the request message, with the node identifier and the outlink
20 MTU of each node included in the request message at the respective node. The
arrows in the direction from the second terminal node T2 to the first terminal node
T1 are indicative of the response message, with the node identifier and the outlink
MTU of each node included in the response message at the respective node.
[0082] Figure 4 illustrates transmission of an IP packet between the first
25 terminal node T1 and the second terminal node T2 based on the set of
fragmentation nodal points for the direction from the first terminal node T1 to the
second terminal node T2, in accordance with an implementation of the present
subject matter. In Figure 4, the examples of fragmentation nodal points and the
corresponding RP-MTUs are with reference to the values in Table 4. As
30 illustrated in Figure 4, with reference to Table 4, the first terminal node T1, router
R5, and R10 are the fragmentation nodal points. The IP packets from T1 to R5
31
may be fragmented based on the RP-MTU of 3000 bytes. The IP packets from R5
to R10 may be fragmented based on the RP-MTU of 1400 bytes. And, the IP
packets from R10 to T2 may be fragmented based on the RP-MTU of 576 bytes.
[0083] Tables 6 and 7 illustrates data for comparing the total number of
fragmentation nodal points that may exist, and the total number of fragments 5 or
fragmented packets that may move in a packet transmission path in case of IPv4
framework implementation, IPv6 framework implementation, and selective
fragmentation implementation of the present subject matter. The example
described through Tables 6 and 7 is for fragmentation and transmission of IP
10 packets in the direction from the first terminal node T1 to the second terminal
node T2.
[0084] Table 6 illustrates the RP-MTUs applicable at each of the nodes in the
packet transmission path for the selective fragmentation implementation with
reference to the example described through Tables 1 to 4. Table 6 also illustrates
15 the outlink MTUs applicable at each of the nodes for the IPv4 framework
implementation and for the IPv6 framework implementation, with reference to the
same example. Considering an example payload size of 20000 bytes for the initial
IP packets to be transmitted across the packet transmission path, Table 7
illustrates the number of fragments handled at each node for the selective
20 fragmentation implementation, IPv4 framework implementation, and IPv6
framework implementation.
Table 6
Node
Identifier
Outlink
MTU (bytes)
RP-MTU
(bytes)
Outlink
MTU for
IPv4 (bytes)
Outlink
MTU for
IPv6 (bytes)
IDT1 9000 3000 9000 576
IDR1 8000 3000 8000 576
IDR2 6000 3000 6000 576
IDR3 5500 3000 5500 576
IDR4 3000 3000 3000 576
32
IDR5 1400 1400 1400 576
IDR6 1450 1400 1400 576
IDR7 1480 1400 1400 576
IDR8 1500 1400 1400 576
IDR9 1470 1400 1400 576
IDR10 576 576 576 576
Table 7
Number of fragments at each node when payload size of
initial IP packet of 20000 bytes
Node
Identifier
For selective
fragmentation
For IPv4 For IPv6
IDT1 7 3 35
IDR1 7 3 35
IDR2 7 4 35
IDR3 7 4 35
IDR4 7 7 35
IDR5 15 15 35
IDR6 15 15 35
IDR7 15 15 35
IDR8 15 15 35
IDR9 15 15 35
IDR10 35 35 35
[0085] It can be noted from Table 6 that for the selective fragmentation
implementation, the number of fragmentation nodal points are three, i.e., at 5 T1,
R5, and R10, as identified in accordance with the present subject matter. The RPMTU
of 3000 bytes, 1400 bytes, and 576 bytes are applicable for the nodes from
T1 to R4, for the nodes from R5 to R9, and at R10, as determined in accordance
with the present subject matter. For the IPv4 framework implementation, the IP
33
packets are fragmented at each node depending on the outlink MTU of the
respective node. Thus, the outlink MTUs applicable at the nodes for the IPv4
framework are the same as the actual outlink MTUs of the nodes. With this, the
number of fragmentation nodal points for the IPv4 framework implementation are
seven, i.e., at T1, R1, R2, R3, R4, R5, and R10. Further, for the 5 e IPv6 framework
implementation, the IP packets are fragmented at the source node depending on
the minimum outlink MTU. Thus, the outlink MTUs applicable at each node for
the IPv6 framework implementation is the outlink MTU of 576 bytes for R10, and
the number of the fragmentation nodal points is one.
10 [0086] Further, it can be noted from Table 7 that the aggregate of total number
of fragments that moves in the packet transmission path for the selective
fragmentation implementation of the present subject matter is 145. The aggregate
of total number of fragments for the IPv4 framework implementation is 131, and
the same for the IPv6 framework implementation is 385.
15 [0087] Thus, to compare the data from Tables 6 and 7, the total number of
fragmentation nodal points for the selective fragmentation implementation of
present subject matter is much less than that for the IPv4 framework
implementation. Further, the total number of fragments for the selective
fragmentation implementation of the present subject matter is much less than that
20 for the IPv6 framework implementation.
[0088] Figure 5 illustrates a comparison of bandwidth utilization for IPv4
framework, for IPv6 framework, and selective fragmentation of the present
subject matter, with respect to an example considered in the description herein.
The bandwidth utilization for the IPv4 framework is depicted by 502, where the
25 IP packets are fragmented at T1, R1, R2, R3, R4, R5, and R10. The bandwidth
utilization for the IPv6 framework is depicted by 504, where the IP packets are
fragmented only at T1. The bandwidth utilization for the selective fragmentation
is depicted by 506. It may be noted that the bandwidth utilization with respect to
the number of fragmentation nodal points is substantially efficient for the
30 selective fragmentation of the present subject matter in comparison to that for the
IPv4 and IPv6 frameworks.
34
[0089] Figures 6(a) and 6(b) illustrate an exemplary method 600 for
fragmentation of IP packets for transmission between two terminal nodes in an IP
network, in accordance with an implementation of the present subject matter. The
order in which the method 600 is described is not intended to be construed as a
limitation, and any number of the described method blocks can be combined 5 ed in
any order to implement the method 600 or any alternative method. Additionally,
individual blocks may be deleted from the method 600 without departing from the
scope of the subject matter described herein. Furthermore, the method 600 can be
implemented in any suitable hardware, software, firmware, or combination
10 thereof.
[0090] The method 600 may be described in the general context of computer
executable instructions. Generally, computer executable instructions can include
routines, programs, objects, components, data structures, procedures, modules,
functions, etc., that perform particular functions or implement particular abstract
15 data types. The method 600 may also be practiced in a distributed computing
environment where functions are performed by remote processing devices that are
linked through a communications network. In a distributed computing
environment, computer executable instructions may be located in both local and
remote computer storage media, including memory storage devices.
20 [0091] A person skilled in the art will readily recognize that steps of the
method 600 can be performed by programmed computers. Herein, some
implementations are also intended to cover program storage devices or computer
readable medium, for example, digital data storage media, which are machine or
computer readable and encode machine-executable or computer-executable
25 programs of instructions, where said instructions perform some or all of the steps
of the described method. The program storage devices may be, for example,
digital memories, magnetic storage media, such as a magnetic disks and magnetic
tapes, hard drives, or optically readable digital data storage media. The
implementations are also intended to cover both communication network and
30 communication devices to perform said steps of the method.
35
[0092] Although the method 600 for fragmentation of IP packets may be
implemented in a variety of computing devices working in different network
environments; in an implementation described in Figures 6(a) and 6(b), the
method 600 is explained in context of the aforementioned terminal node 102 in
the network communication link 100 of an IP network for the ease of explan5 ation.
[0093] Referring to Figure 6(a), at block 602, outlink MTUs of nodes in a
packet transmission path between a first terminal node 102-1 and a second
terminal node 102-2 in the IP network are obtained, wherein the nodes include
routers 104 and at least one of the first terminal node 102-1 and the second
10 terminal node 102-2. In an implementation, the outlink MTUs are obtained for the
nodes in a direction from the first terminal node 102-1 to the second terminal node
102-2, or from the second terminal node 102-2 to the first terminal node 102-1, or
both. The node identifiers of the nodes may also be obtained in addition to the
outlink MTUs. In an implementation, the node identifiers and the outlink MTUs
15 of the nodes may be obtained at the first terminal node 102-1 based on the ICMP
based request message and the ICMP based response message as described earlier
in the description.
[0094] At block 604, a permissible outlink payload for each of the nodes is
determined. The permissible outlink payload for the each node may be determined
20 at the first terminal node 102-1 based on the outlink MTUs of the nodes as
described earlier in the description.
[0095] At block 606, an MTU degradation factor is determined for each of the
nodes. The MTU degradation factor for the each node may be determined at the
first terminal node 102 based on the permissible outlink payloads as described
25 earlier in the description.
[0096] Further, at block 608, a set of fragmentation nodal points is identified
for fragmentation of IP packets during transmission between the first terminal
node 102-1 and the second terminal node 102-2. The set of fragmentation nodal
points includes one of the first terminal node and the second terminal node, and
30 the routers for which the MTU degradation factor is one of more than and equal to
a predefined threshold MTU degradation factor. In an implementation, the set of
36
fragmentation nodal points may be identified at the first terminal node 102-1 in a
manner as described earlier in the description. The sets of fragmentation nodal
points for the direction from the first terminal node 102-1 to the second terminal
node 102-2 and for the direction from the second terminal node 102-2 to the first
terminal node 102-1 may be identified separately5 .
[0097] Further, at block 610, the set of fragmentation nodal points is
normalized based on at least one of the normalization conditions, as described
earlier in the description. In an implementation, the normalization of the set of
fragmentation nodal points may be done at the first terminal node 102-1. Further,
10 at block 612, a RP-MTU is determined for each fragmentation nodal point in the
set. In an implementation, the RP-MTUs may be determined at the first terminal
node 102-1. The normalized set of fragmentation nodal points refers to the nodes
at which the IP packets may be fragmented in the packet transmission path
between the terminal nodes 102-1 and 102-2, and the RP-MTUs associated with
15 the fragmentation nodal points refer to the outlink MTUs based on which the IP
packets may be fragmented at the fragmentation nodal points.
[0098] Referring to Figure 6(b), at block 614, it is check whether a payload
size of an IP packet is more than a minimum RP-MTU from amongst RP-MTUs
for the fragmentation nodal points. If the payload size is less (‘no’ branch from
20 block 614), then a do-not-fragment bit in a packet header of the IP packet is set at
block 616. If the payload size is more (‘yes’ branch from block 614), then the donot-
fragment bit in a packet header of the IP packet is unset at block 618. At block
620, the node identifiers and the RP-MTUs associated with the fragmentation
nodal points are added in the packet header of the IP packet for the purposes of
25 fragmentation of the IP packet over the packet transmission path. The node
identifiers and the RP-MTUs for the set of fragmentation nodal points identified
for the direction from the first terminal node 102-1 to the second terminal node
102-2, and for the set of fragmentation nodal points identified for the direction
from the second terminal node 102-2 to the first terminal node 102-1 may be
30 added in the packet header of the IP packet.
37
[0099] After setting or unsetting the do-not-fragment bit and accordingly
including the information associated with the set of fragmentation nodal points in
the packet headers of the IP packets, at the first terminal node 102-1 if the payload
size of the IP packet is less than or equal to the minimum RP-MTU, then the IP
packet is transmitted to the next node, i.e., router R1 without any fragmentation5 .
Else, if the payload size of the IP packet is more than the minimum RP-MTU,
then the payload size of the IP packet is compared with the RP-MTU for the first
terminal node 102-1. If the payload size of the IP packet is less than or equal to
the RP-MTU, then the IP packet is transmitted to router R1 without
10 fragmentation, and if the payload size is more than the RP-MTU, then the IP
packet is fragmented according to the RP-MTU.
[00100] Further, at each of the routers 104 in the packet transmission path the
do-not-fragment bit of each IP packet, received at the respective router 104, is
checked. If the do-not-fragment bit is set in an IP packet, then the IP packet is
15 transmitted to the next node without any fragmentation. Else, if the do-notfragment
bit is unset, then the packet header of the IP packet is scanned to check
whether the respective router 104 is a fragmentation nodal point. If the respective
router 104 is a fragmentation nodal point, the RP-MTU associated with the
respective router 104 is derived from the packet header. Subsequently, the
20 payload size of the IP packet is compared with the RP-MTU for the respective
router 104. If the payload size of the IP packet is less than or equal to the RPMTU,
then the IP packet is transmitted without fragmentation, and if the payload
size is more than the RP-MTU, then the IP packet is fragmented according to the
RP-MTU.
25 [00101] Further, in an implementation, if a router 104 is a fragmentation nodal
point, then, at the router 104, the RP-MTU for the router 104 is compared with the
outlink MTU of the router 104. If the outlink MTU of the router 104 is less than
its RP-MTU, then IP packets may be fragmented and transmitted based on default
framework, i.e., one of the IPv4 or IPv6 frameworks. In an example, if the IPv6
30 framework is the default framework for the IP network, then an error message is
sent to the source node, which may indicate to the failure of transmission of IP
38
packets. In an example, if the IPv4 framework is the default framework for the IP
network, then the IP packet may be fragmented based on the outlink MTU of the
router 104.
[00102] Although implementations for fragmentation of IP packets for
transmission between two terminal nodes in an IP network have been described 5 d in
a language specific to structural features or method(s), it is to be understood that
the present subject matter is not limited to the specific features or method(s)
described. Rather, the specific features and methods are disclosed as
implementations for fragmentation of IP packets for transmission between two
10 terminal nodes in an IP network.

CLAIMS:1. A method for fragmentation of internet protocol (IP) packets for transmission between two terminal nodes (102-1, 102-2) in an IP network, the method comprising:
obtaining, at a first terminal node (102-1), outlink maximum transmission units (MTUs) of nodes in a packet transmission path between the first terminal node (102-1) and a second terminal node (102-2) in the IP network, wherein the nodes comprise intermediate network nodes (104) and at least one of the first terminal node (102-1) and the second terminal node (102-2);
determining, at the first terminal node (102-1), a permissible outlink payload for each of the nodes, wherein the permissible outlink payload for the each node is a minimum outlink MTU from amongst the outlink MTU of the respective node and the outlink MTUs of nodes prior to the respective node in the packet transmission path;
determining, at the first terminal node (102-1), an MTU degradation factor for each of the nodes, wherein the MTU degradation factor for the each node is determined based on a ratio of the permissible outlink payload for the respective node to the permissible outlink payload for a prior node adjacent to the respective node in the packet transmission path, wherein the MTU degradation factor for a node indicates whether the node is a bottleneck for the IP packets in the packet transmission path; and
identifying, at the first terminal node (102-1), a set of fragmentation nodal points for fragmentation of IP packets during transmission between the first terminal node (102-1) and the second terminal node (102-2), the set of fragmentation nodal points comprising:
one of the first terminal node (102-1) and the second terminal node (102-2); and
the intermediate network nodes (104) having the MTU degradation factor as one of more than and equal to a predefined threshold MTU degradation factor.
2. The method as claimed in claim 1, wherein the identifying the set of fragmentation nodal points comprises normalizing the set of fragmentation nodal points based on at least one of:
when the set of fragmentation nodal points comprises consecutive intermediate network nodes, retaining one of the consecutive intermediate network nodes that is closer to a destination node in the packet transmission path and dropping other nodes of the consecutive intermediate network nodes from the set of fragmentation nodal points;
when the set of fragmentation nodal points has two vicinity intermediate network nodes separated by at most a predefined number of intermediate network nodes, retaining one of the two vicinity intermediate network nodes that is closer to the destination node in the packet transmission path and dropping other of the two vicinity intermediate network nodes from the set of fragmentation nodal points; and
when a number of fragmentation nodal points is more than a predefined permissible number of fragmentation nodal points, dropping the intermediate network nodes with least MTU degradation factors till the number of fragmentation nodal points is equal to the predefined permissible number of fragmentation nodal points.
3. The method as claimed in claim 1 further comprising:
determining, at the first terminal node (102-1), a revised permissible outlink MTU (RP-MTU) for each fragmentation nodal point in the set,
wherein the RP-MTU for the each fragmentation nodal point, except last fragmentation nodal point, is the permissible outlink payload of a node prior to a subsequent fragmentation nodal point,
wherein the RP-MTU for the last fragmentation nodal point is the permissible outlink payload of last intermediate network node prior to a destination node in the packet transmission path, and
wherein the fragmentation of IP packets is based on the RP-MTU of fragmentation nodal points in the set.
4. The method as claimed in claim 3, wherein the outlink MTUs of the nodes are for packet transmission from the first terminal node (102-1) to the second terminal node (102-2), wherein the obtaining the outlink MTUs comprises:
sending an internet control message protocol (ICMP) based request message from the first terminal node (102-1) to the second terminal node (102-2) through the nodes in the packet transmission path, wherein the ICMP request message has a type value of one of 41 to 255 indicating to include, at the each node, the outlink MTU and a node identifier of the respective node in the ICMP based request message; and
receiving an ICMP based response message at the first terminal node (102-1) from the second terminal node (102-2), wherein the ICMP based response message comprises the outlink MTUs and node identifiers of the nodes from the first terminal node (102-1) to the second terminal node (102-2).
5. The method as claimed in claim 4, wherein the set of fragmentation nodal points comprise the first terminal node (102-1) and indicate nodes for fragmentation of IP packets for packet transmission from the first terminal node (102-1) to the second terminal node (102-2), and wherein the method further comprises:
when a payload size of an IP packet is more than a minimum RP-MTU from amongst RP-MTUs for the fragmentation nodal points, unsetting a do-not-fragment bit in a packet header of the IP packet; and
adding node identifiers and the RP-MTUs associated with the fragmentation nodal points in the packet header of the IP packet for fragmentation of the IP packet.
6. The method as claimed in claim 3, wherein the outlink MTUs of the nodes are for packet transmission from the second terminal node (102-2) to the first terminal node (102-1), wherein the obtaining the outlink MTUs comprises:
sending an ICMP based request message from the first terminal node (102-1) to the second terminal node (102-2); and
receiving an ICMP based response message at the first terminal node (102-1) from the second terminal node (102-2) through the nodes in the packet transmission path, wherein the ICMP based response message has a type value of one of 41 to 255 indicating to include, at the each node, the outlink MTU and a node identifier of the respective node in the ICMP based response message.
7. The method as claimed in claim 6, wherein the set of fragmentation nodal points comprise the second terminal node (102-2) and indicate nodes for fragmentation of IP packets for packet transmission from the second terminal node (102-2) to the first terminal node (102-1), and wherein the method further comprises:
adding node identifiers and the RP-MTUs associated with the fragmentation nodal points in a packet header of an IP packet for fragmentation of the IP packet for the packet transmission from the second terminal node (102-2) to the first terminal node (102-1).
8. The method as claimed in claim 1, wherein the MTU degradation factor for the each node is based on one minus the ratio of the permissible outlink payload for the respective node to the permissible outlink payload for a prior node adjacent to the respective node in the packet transmission path.
9. A terminal node (102) in an IP network, the terminal node (102) comprising:
a processor (202); and
a fragmentation nodes identification module (106) coupled to the processor (202) to
obtain outlink maximum transmission units (MTUs) of nodes in a packet transmission path between the terminal node (102) and other terminal node in the IP network, wherein the nodes comprise intermediate network nodes (104) and at least one of the terminal node (102) and the other terminal node;
determine a permissible outlink payload for each of the nodes, wherein the permissible outlink payload for the each node is a minimum outlink MTU from amongst the outlink MTU of the respective node and the outlink MTUs of nodes prior to the respective node in the packet transmission path;
determine an MTU degradation factor for the each of the nodes, wherein the MTU degradation factor for the each node is determined based on a ratio of the permissible outlink payload for the respective node to the permissible outlink payload for a prior node adjacent to the respective node in the packet transmission path, wherein the MTU degradation factor for a node indicates whether the node is a bottleneck for IP packets in the packet transmission path; and
identify a set of fragmentation nodal points for fragmentation of IP packets during transmission between the terminal node (102) and the other terminal node, the set of fragmentation nodal points comprising:
one of the terminal node (102) and the other terminal node; and
the intermediate network nodes (104) having the MTU degradation factor as one of more than and equal to a predefined threshold MTU degradation factor.
10. The terminal node (102) as claimed in claim 9, wherein the fragmentation nodes identification module (106) is coupled to the processor (202) to normalize the set of fragmentation nodal points based on at least one of:
when the set of fragmentation nodal points comprises consecutive intermediate network nodes, retaining one of the consecutive intermediate network nodes that is closer to a destination node in the packet transmission path and dropping other nodes of the consecutive intermediate network nodes from the set of fragmentation nodal points;
when the set of fragmentation nodal points has two vicinity intermediate network nodes separated by at most a predefined number of intermediate network nodes, retaining one of the two vicinity intermediate network nodes that is closer to the destination node in the packet transmission path and dropping other of the two vicinity intermediate network nodes from the set of fragmentation nodal points; and
when a number of fragmentation nodal points is more than a predefined permissible number of fragmentation nodal points, dropping the intermediate network nodes with least MTU degradation factors till the number of fragmentation nodal points is equal to the predefined permissible number of fragmentation nodal points.
11. The terminal node (102) as claimed in claim 9, wherein the fragmentation nodes identification module (106) is coupled to the processor (202) to determine a revised permissible outlink MTU (RP-MTU) for each fragmentation nodal point in the set, wherein the RP-MTU for the each fragmentation nodal point, except last fragmentation nodal point, is the permissible outlink payload of a node prior to a subsequent fragmentation nodal point, and wherein the RP-MTU for the last fragmentation nodal point is the permissible outlink payload of last intermediate network node prior to a destination node in the packet transmission path, and wherein the fragmentation of IP packets is based on the RP-MTU of fragmentation nodal points in the set.
12. The terminal node (102) as claimed in claim 11, wherein the outlink MTUs of the nodes are for packet transmission from the terminal node (102) to the other terminal node, wherein the fragmentation nodes identification module (106) is coupled to the processor (202) to:
send an internet control message protocol (ICMP) based request message to the other terminal node through the nodes in the packet transmission path, wherein the ICMP request message has a type value of one of 41 to 255 indicating to include, at the each node, the outlink MTU and a node identifier of the respective node in the ICMP based request message; and
receive an ICMP based response message from the other terminal node, wherein the ICMP based response message comprises the outlink MTUs and node identifiers of the nodes from the terminal node (102) to the other terminal node.
13. The terminal node (102) as claimed in claim 12, wherein the set of fragmentation nodal points comprise the terminal node (102) and indicate nodes for fragmentation of IP packets for packet transmission from the terminal node (102) to the other terminal node, and wherein the terminal node (102) further comprises a packet processing module (212) coupled to the processor (202) to:
unset a do-not-fragment bit in a packet header of an IP packet when a payload size of the IP packet is more than a minimum RP-MTU from amongst RP-MTUs for the fragmentation nodal points; and
add node identifiers and the RP-MTUs associated with the fragmentation nodal points in the packet header of the IP packet for fragmentation of the IP packet.
14. The terminal node (102) as claimed in claim 11, wherein the outlink MTUs of the nodes are for packet transmission from the other terminal node to the terminal node (102), wherein the fragmentation nodes identification module (106) is coupled to the processor (202) to:
send an ICMP based request message to the other terminal node; and
receive an ICMP based response message from the other terminal node through the nodes in the packet transmission path, wherein the ICMP based response message has a type value of one of 41 to 255 indicating to include, at the each node, the outlink MTU and a node identifier of the respective node in the ICMP based response message.
15. The terminal node (102) as claimed in claim 14, wherein the set of fragmentation nodal points comprise the other terminal node and indicate nodes for fragmentation of IP packets for packet transmission from the other terminal node to the terminal node (102), and wherein the terminal node (102) further comprises a packet processing module (212) coupled to the processor (202) to:
add node identifiers and the RP-MTUs associated with the fragmentation nodal points in a packet header of an IP packet for fragmentation of the IP packet for the packet transmission from the other terminal node to the terminal node (102).
16. A non-transitory computer-readable medium having embodied thereon a computer program for executing a method for fragmentation of internet protocol (IP) packets for transmission between two terminal nodes (102-1, 102-2) in an IP network, the method comprising:
obtaining outlink maximum transmission units (MTUs) of nodes in a packet transmission path between a first terminal node (102-1) and a second terminal node (102-2) in the IP network, wherein the nodes comprise intermediate network nodes (104) and at least one of the first terminal node (102-1) and the second terminal node (102-2);
determining a permissible outlink payload for each of the nodes, wherein the permissible outlink payload for the each node is a minimum outlink MTU from amongst the outlink MTU of the respective node and the outlink MTUs of nodes prior to the respective node in the packet transmission path;
determining an MTU degradation factor for each of the nodes, wherein the MTU degradation factor for the each node is determined based on a ratio of the permissible outlink payload for the respective node to the permissible outlink payload for a prior node adjacent to the respective node in the packet transmission path, wherein the MTU degradation factor for a node indicates whether the node is a bottleneck for the IP packets in the packet transmission path; and
identifying a set of fragmentation nodal points for fragmentation of IP packets during transmission between the first terminal node (102-1) and the second terminal node (102-2), the set of fragmentation nodal points comprising:
one of the first terminal node (102-1) and the second terminal node (102-2); and
the intermediate network nodes (104) having the MTU degradation factor as one of more than and equal to a predefined threshold MTU degradation factor.
17. The non-transitory computer-readable medium as claimed in claim 16, wherein the method further comprises:
determining a revised permissible outlink MTU (RP-MTU) for each fragmentation nodal point in the set, wherein the RP-MTU for the each fragmentation nodal point, except last fragmentation nodal point, is the permissible outlink payload of a node prior to a subsequent fragmentation nodal point, and wherein the RP-MTU for the last fragmentation nodal point is the permissible outlink payload of last intermediate network node prior to a destination node in the packet transmission path, and wherein the fragmentation of IP packets is based on the RP-MTU of fragmentation nodal points in the set.
18. The non-transitory computer-readable medium as claimed in claim 16, wherein the MTU degradation factor for the each node is based on one minus the ratio of the permissible outlink payload for the respective node

to the permissible outlink payload for a prior node adjacent to the respective node in the packet transmission path.