FIELD OF INVENTION
[0001] The present subject matter relates to connectivity fault management in
communication networks and, more particularly but not exclusively, to discovery o5 f
maintenance end points for connectivity fault management in communication networks.
BACKGROUND
[0002] A communication network typically includes one or more network devices,
such as data switches, gateways, routers, and bridges to which users may connect for using
10 the communication network. Such network devices typically interact with each other over a
communication link for exchanging data associated with the users. Network providers usually
monitor these network devices to ensure a high level of quality of service. One of the
measures taken by the network providers includes implementing a connectivity fault
management (CFM) protocol to monitor the connectivity between the network devices
15 associated with the same communication link. Implementing the CFM protocols involves
installing maintenance end points (MEPs) modules in the network devices installed at the end
points of the communication link and installing maintenance intermediate points (MIPs) in
the network devices installed in between the communication link. The CFM protocol
involves transmission of one or more periodic messages, such as continuity check messages
20 (CCM), loopback messages, and link trace messages between the MEPs and MIPs belonging
to the same communication link. Based on success or failure of the transmission and
reception of these messages between the MEPs, the network provider may determine the
connectivity status of the network devices on which the MEPs are installed.
SUMMARY
25 [0003] This summary is provided to introduce concepts related to systems and
methods for maintenance end points discovery for connectivity fault management in
communication networks. This summary is neither intended to identify features of the
claimed subject matter nor is it intended for use in determining or limiting the scope of the
claimed subject matter.
3
[0004] In one implementation, a method for discovering maintenance end points for
connectivity fault management in a communication network is described. The method
includes generating, by a first maintenance end point (MEP), a loopback message having a
maintenance association identifier (MAID) corresponding to a maintenance association to
which the first MEP belongs. The method further includes multicasting, by the first MEP, th5 e
loopback message to one or more other MEPs registered with a maintenance domain (MD)
level with which the first MEP is registered. Further the method includes receiving, by the
first MEP, a loopback reply message from at least one other MEP from among the one or
more other MEPs, where the at least one other MEP has the same MAID as the first MEP.
10 The method further includes determining, by the first MEP, the at least one other MEP to
belong to the same maintenance association to which the first MEP belongs based on the
receiving, wherein the at least one other MEP is ascertained as a remote MEP with which the
first MEP may exchange connectivity fault management messages for connectivity fault
management.
15 [0005] In another implementation, a network device implementing a first maintenance
end point (MEP) is described. The network device comprises a processor and a message
generation module coupled to the processor to generate a loopback message having a
maintenance association identifier (MAID) corresponding to a maintenance association to
which the first MEP belongs. The network device further includes a networking module
20 coupled to the processor to multicast the loopback message to one or more other network
devices, where each of the one or more network devices implements a MEP registered with a
maintenance domain (MD) level with which the first MEP is registered. The networking
module further receive a loopback reply message from at least one other network device from
among the one or more other network devices, where the at least one other network device
25 implements a second MEP having the same MAID as the first MEP. The network device
further includes a processing module coupled to the processor to determine, based on the
receiving, the second MEP to belong to the same maintenance association to which the first
MEP belongs, where the second MEP is ascertained as a remote MEP with which the first
MEP exchanges connectivity fault management messages for connectivity fault management.
30 [0006] In another implementation, a method for discovering maintenance end points
for connectivity fault management in a communication network is described. The method
includes analyzing, by a first maintenance end point (MEP), a loopback message received
from a second MEP to obtain a maintenance association identifier (MAID) corresponding to
4
a maintenance association to which the second MEP belongs. Further, the method comprises
comparing the MAID of the second MEP with a MAID of the first MEP to determine if the
second MEP and the first MEP belong to the same maintenance association. The method
further comprises transmitting, by the first MEP, a loopback reply (LBR) message to the
second MEP based on the determination, wherein the LBR message includes a MEPID of th5 e
first MEP, where the MEPID of the first MEP is used by the second MEP for exchanging
connectivity fault management messages for connectivity fault management.
[0007] In yet another implementation, a non-transitory computer-readable medium
having embodied thereon a computer program for executing a method for discovering
10 maintenance end points for connectivity fault management in a communication network is
described. The method includes generating, by a first maintenance end point (MEP), a
loopback message having a maintenance association identifier (MAID) corresponding to a
maintenance association to which the first MEP belongs. The method further includes
multicasting, by the first MEP, the loopback message to one or more other MEPs registered
15 with a maintenance domain (MD) level with which the first MEP is registered. Further the
method includes receiving, by the first MEP, a loopback reply message from at least one
other MEP from among the one or more other MEPs, where the at least one other MEP has
the same MAID as the first MEP. The method further includes determining, by the first MEP,
the at least one other MEP to belong to the same maintenance association to which the first
20 MEP belongs based on the receiving, wherein the at least one other MEP is ascertained as a
remote MEP with which the first MEP exchanges connectivity fault management messages
for connectivity fault management.
[0008] In yet another implementation, a non-transitory computer-readable medium
having embodied thereon a computer program for executing a method for discovering
25 maintenance end points for connectivity fault management in a communication network is
described. The method includes analyzing, by a first maintenance end point (MEP), a
loopback message received from a second MEP to obtain a maintenance association identifier
(MAID) corresponding to a maintenance association to which the second MEP belongs.
Further, the method comprises comparing the MAID of the second MEP with a MAID of the
30 first MEP to determine if the second MEP and the first MEP belong to the same maintenance
association. The method further comprises transmitting, by the first MEP, a loopback reply
(LBR) message to the second MEP based on the determination, wherein the LBR message
includes a MEPID of the first MEP, where the MEPID of the first MEP is used by the second
5
MEP for exchanging connectivity fault management messages for connectivity fault
management.
BRIEF DESCRIPTION OF THE FIGURES
[0009] The detailed description is described with reference to the accompanying
figures. In the figures, the left-most digit(s) of a reference number identifies the figure i5 n
which the reference number first appears. The same numbers are used throughout the figures
to reference like features and components. Some embodiments of system or methods in
accordance with embodiments of the present subject matter are now described, by way of
example, and with reference to the accompanying figures, in which:
10 [0010] Fig. 1 illustrates a network environment implementing one or more network
devices for discovery of maintenance end points, in accordance with an embodiment of the
present subject matter;
[0011] Fig. 2 illustrates a method for discovery of maintenance end points for
connectivity fault management, in accordance with an embodiment of the present subject
15 matter; and
[0012] Fig. 3 illustrates a method for discovery of maintenance end points for
connectivity fault management, in accordance with an embodiment of the present subject
matter.
[0013] It should be appreciated by those skilled in the art that any block diagrams
20 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 readable medium and so executed by a computer or
processor, whether or not such computer or processor is explicitly shown.
25 DESCRIPTION OF EMBODIMENTS
[0014] Systems and methods for maintenance end points discovery for connectivity
fault management (CFM) in communication networks are described. CFM is a well known
protocol defining a number of proactive and diagnostic fault localization procedures for
monitoring and troubleshooting a communication network, such as an Ethernet network. The
6
CFM protocol is typically implemented using two types of networking entities, the
maintenance end points (MEPs) and maintenance intermediate points (MIPs). The MEPs and
MIPs may be understood as networking entities operating within a network device, such as
data switches, gateways, routers, and bridges. The MEPs are implemented in network device
installed at a boundary of the communication network and interacting with each other over 5 a
communication link for exchanging data. The MIPs are implemented in the network devices
installed in between the communication links. As will be understood, the CFM protocol is
typically implemented to identify any faults in connectivity between two MEPs, i.e., to
determine whether a network connection between two MEPs or MIPs is working properly or
10 not. In case there is any fault in the connection, the CFM protocol also helps in identifying a
faulty section of the network that is causing the network connectivity problem. Further, such
connectivity checks are typically periodic checks conducted by exchanging one or more CFM
messages between two MEPs. The CFM messages, however, may also be sent based on
network requirements, for example, on receiving complaints of data loss.
15 [0015] Further as specified in IEEE 802.1ag standard, the MEPs and MIPs are
grouped into one or more maintenance associations (MAs), and each of such MAs are further
grouped into one or more maintenance domain levels. A maintenance domain (MD) may be
defined as a management space on a communication network, typically owned and operated
by a single entity, say, a service provider, and defined by a set of internal boundary ports or
20 network devices. The maintenance domains are classified into eight levels ranging from level
0 to level 7 depending upon the size of the maintenance domain. Therefore larger the
maintenance domain, higher is its level. For instance, in a scenario where a customer may
subscribe to the services offered by a service provider and the service provider, in turn, may
subscribe to the services of multiple operators, a customer domain owing to its size may be at
25 a MD level 7, a service provider domain may be at a MD level 3, and an operator domain
may be at a MD level 0. Further, each MD level includes one or more maintenance
associations such that all MEPs implemented at the particular MD level are grouped in the
one or more maintenance associations belonging to the particular MD level.
[0016] In order to check network connectivity as per the CFM protocols, the MEPs
30 and MIPs belonging to the same maintenance association exchange one or more CFM
messages, such as continuity check messages (CCM), loopback messages, and link trace
messages with each other. The CCM are periodic messages transmitted at a predetermined
7
rate by an MEP within a maintenance association to detect connectivity failures and also
detect other MEPs. The CCM are multicast messages received by all MIPs and MEPs in the
maintenance domain receive. The loopback message is transmitted by a first MEP to a second
MEP or MIP to identify a precise fault location in the MA to which the MEP belongs. If the
second MEP or MIP responds with a loopback reply, the first MEP determines that th5 e
second MEP is located before the fault, otherwise the first MEP determines that second MEP
is located after the fault in case the first MEP does not receive any message. The link trace
message is used by the first MEP to trace a path to the second MEP or MIP in the same
maintenance domain. All intermediate MIPs between the first MEP and the second MEP
10 respond back to the first MEP with a linktrace reply based on which the first MEP may
determine the media access control (MAC) address of all MIPs along the MA, and their
precise location with respect to the first MEP.
[0017] Detecting network failures using the CFM messages, especially the loopback
messages and the linktrace messages, however, requires the first MEP to know an MEP
15 identifier (MEPID) of the second MEP in order to send the CFM message to the second
MEP. Conventional methods used for determining MEPID of the second MEP involves a
remote access login of all MEPs by the first MEP to determine whether the MEP belongs to
the same MA as of the first MEP. In case the MEP belongs to the same MA, the first MEP
may obtain the MEPID from internal storage of the MEP. Remote login of the other MEPs,
20 however, requires the first MEP to know access information, such as a username, a password,
and an IP address of each of the MEP. Such access information may, however, not always be
available with first MEP making it difficult for the MEP to determine the MEPIDs of the
other MEP. Further, provisioning engine/management systems may be implemented by the
network providers to determine access the MEPs for obtaining the MEPIDs. Such systems
25 may however not be able to efficiently obtain the MEPIDs due to unavailability of login
credentials, such as username and password of the MEPs with the provisioning
engine/management systems.
[0018] Another conventional method used, by an MIP, for discovering the MEPs
belonging to the same MA and their corresponding MEPIDs involves analyzing the CCM
30 messages transmitted by the MEPs. As previously described, the CCM messages are periodic
multicast messages transmitted by an MEP within its MA. The CCM message typically
includes the MEPID of the transmitting MEP that maybe used by the receiving MEP to
8
update an internal database of the MEPIDs of the MEPs belonging the same MA. The CCM
messages are, however, optional CFM messages that some maintenance domain may not
implement. The MEPs in such a case may thus not be able to automatically determine the
MEPID of the MEPs belonging to the same MA.
[0019] According to an implementation of the present subject matter, systems an5 d
methods for discovering maintenance end points for connectivity fault management in
communication networks are described. In one embodiment, a first MEP intending to
discover all MEPs that belong to the same MA to which the first MEP belongs sends a
multicast message to all MEPs belonging to the same maintenance domain. On receiving the
10 multicast message, the MEPs belonging to the same MA as the first MEP may send a reply to
the first MEP. The first MEP may then analyze the reply to obtain an MEPID of the MEP
from which it received the reply. Each MEP may thus automatically discover remote MEPs,
belonging to the same MA as theirs, for conducting connectivity fault management.
[0020] According to one embodiment of the subject matter, one or more network
15 devices, such as data switches, gateways, routers, and bridges installed in a communication
network and having installed the MEP may utilize an MEP discovery mechanism to discover
MEPs that belong to the same MA as that of the MEP initiating the MEP discovery
mechanism. As will be understood, the MEPs are grouped into one or more different MAs
which are further grouped into one or more MD levels, such that all MEPs belonging to the
20 same MA at the same MD level interact with each other for connectivity fault management.
Further, each MEP is assigned an MEPID, unique to the MEP, and an MA identifier (MAID)
common to all MEPs belonging to the same MA.
[0021] In order to discover the MEPs that belong to the same MA, i.e., having the
same MAID, the first MEP may generate a loopback message having the MAID of the MA to
25 which the MEP belongs. The first MEP may then multicast the loopback message to all the
MEPs belonging to the same MD. Upon receiving the loopback message, each of the MEP
may analyze the loopback message to obtain the MAID transmitted by the first MEP. Each of
the MEPs may then compare the MAID with the MAID assigned to it to determine whether
the first MA and the MEP share the same MAID. The MEPs, say a second MEP and a third
30 MEP who have the same MAID as that of the first MEP may then determine that the first
MEP belongs to the same MA as the MEP. The second MEP and the third MEP may then
9
generate a loopback reply (LBR) message having the MAID and the MEPID assigned to
them. The second MEP and the third MEP may then transmit the LBR message to the first
MEP.
[0022] On receiving the LBR message, the first MEP may obtain the MEPID
corresponding to the second MEP and the third MEP from the LBR message and update a5 n
MEP database. In one implementation, the first MEP may initially update an internal MEP
table having MEPID and MAC address of the MEPs having the same MAID as the first
MEP. Once updated, the first MEP may access the internal MEP or the MEP database to
determine the MEPID and the MAC address of all the MEPs to which it may send CFM
10 messages for connectivity fault management.
[0023] The present subject matter thus facilitates maintenance end point discovery in
a communication network. Facilitating the MEPs to transmit a modified loopback message
along with the MAID allows the MEP to automatically discover the remote MEPs. Further,
using a modified loopback message allows the MEPs to discover the remote MEPs without
15 depending on possible periodic updates or costly and resource consuming provisioning
engines and management systems. Additionally, modifying an existing CFM for the
discovery mechanism helps in avoiding implementation of additional protocols or CFM
messages for the MEP discovery mechanism. Furthermore, allowing the MEPs to determine
the MEPIDs of other MEPs belonging to the same MA facilitates in determining whether two
20 or more MEPs have been assigned the same MEPID. In case an MEP determines that an LBR
message received by it has an MEPID same as its MEPID, the MEP may notify a system
administrator that two MEPs belonging to a single MA have been assigned the same MEP.
The system administrator, in such a case, may take one or more pre-determined corrective
measures to ensure that all MEPs belonging to a single MEP are assigned unique MEPIDs.
25 [0024] It should be noted that the description and figures merely illustrate the
principles of the present subject matter. It will thus be 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 and are included within its spirit
and scope. Furthermore, all examples recited herein are principally intended expressly to be
30 for pedagogical purposes to aid the reader in understanding the principles of the present
subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to
10
be construed as being without limitation to such specifically recited examples and conditions.
Moreover, all statements herein reciting principles, aspects, and embodiments of the present
subject matter, as well as specific examples thereof, are intended to encompass equivalents
thereof.
[0025] It will also be appreciated by those skilled in the art that the words during5 ,
while, and when as used herein are not exact terms that mean an action takes place instantly
upon an initiating action but that there may be some small but reasonable delay, such as a
propagation delay, between the initial action and the reaction that is initiated by the initial
action. Additionally, the words “connected” and “coupled” are used throughout for clarity of
10 the description and can include either a direct connection or an indirect connection.
[0026] The manner in which the systems and the methods of channel resource
allocation for device-to-device communication may be implemented has been explained in
details with respect to the Figures 1 to 3. While aspects of described system(s) and method(s)
of the present subject matter can be implemented in any number of different computing
15 systems, environments, and/or configurations, the embodiments are described in the context
of the following system(s).
[0027] Fig. 1 illustrates a network environment 100 implementing one or more
network devices for discovery of maintenance end points, in accordance with an embodiment
of the present subject matter. In said embodiment, one or more network devices 102-1, 102-2,
20 102-3, …., 102-n, hereinafter collectively referred to as network devices 102 and individually
referred to as a network device 102 interact with each other over a communication network
104. In one implementation, the communication network 104 may be an Ethernet network.
Examples of the network devices 102 include, but are not limited to, data switches, gateways,
routers, and bridges to which users may connect for using the communication network.
25 [0028] According to an embodiment of the present subject matter, the network
devices 102 may be installed at a boundary of the communication network 104 and be
accessed by one or more user devices (not shown in the figure) for exchanging data over the
communication network 104. Further a maintenance end point (MEP) 106 may be installed in
each of the network devices 102 for implementing a connectivity fault management (CFM)
30 protocol for the communication network 104. For instance, a MEP 106-1, 106-2, 106-3, ….,
106-n may be installed in the network devices 102-1, 102-2, 102-3, …, 102-n, respectively.
11
Further, as previously described, based on the IEEE 802.1ag standard, the MEPs 106-1, 106-
2, 106-3, …., 106-n, hereinafter collectively referred to as MEPs 106 and individually
referred to as MEP 106, are grouped into one or more maintenance associations (MAs). The
maintenance associations are further grouped into one or more maintenance domain levels
ranging from level 0 to level 7 such that all MEPs 106 implemented at a particular MD leve5 l
are grouped in the one or more maintenance associations belonging to the particular MD
level. Further, each maintenance level may be assigned a unique MA identifier (MAID) such
that all the MEPs 106 belonging to a particular maintenance association may share the same
MAID. Each of the MEPs 106 may be further assigned a MEP identifier (MEPID) such that
10 all MEPs 106 belonging to the same maintenance association have a different MEPID, while
MEPs 106 belonging to different maintenance associations may have same MEPID.
[0029] In one implementation, each of the network devices 102 includes processor(s),
device I/O interface(s), and a device memory coupled to the device processors. For example,
the network device 102-1 includes processor(s) 108-1, I/O interface(s) 110-1, and memory
15 112-1 coupled to the processor 108-1; while the network device 102-2 includes processor(s)
108-2, I/O interface(s) 110-2, and memory 112-2 coupled to the processor 108-2. The
processors for all the network devices 102 are hereinafter collectively referred to as the
processor(s) 108. The I/O interface(s) for all the network devices 102 are hereinafter
collectively referred to as the I/O interface(s) 110 and similarly, the memory for all the
20 network devices 102 are hereinafter collectively referred to as the memory 112. The
processors 108 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) is configured to fetch and execute computer25
readable instructions stored in the memory.
[0030] 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 software in association with appropriate
software. When provided by a processor, the functions may be provided by a single dedicated
30 processor, by a single shared processor, or by a plurality of individual processors, some of
which may be shared.
12
[0031] The I/O interfaces 110 may include a variety of software and hardware
interfaces that allow the network devices 102 to interact with each other and the
communication network 104. Further, the I/O interfaces 110 may enable the network devices
102 to communicate with other communication and computing devices, such as web servers
and external repositories. The memory 112 may include any computer-readable mediu5 m
known in the art including, for example, volatile memory (e.g., RAM), and/or non-volatile
memory (e.g., EPROM, flash memory, etc.).
[0032] Further, each of the network devices 102 includes modules and data. For
example, the network device 102-1 and the network device 102-2 include modules 114-1,
10 114-2 and data 116-1, 116-2, respectively, collectively referred to as modules 114 and data
116, respectively. The modules 114 include routines, programs, objects, components, data
structures, and the like, which perform particular tasks or implement particular abstract data
types. The modules 114 further include modules that supplement applications on the network
devices 102, for example, modules of an operating system.
15 [0033] Further, the modules 114 can be implemented in hardware, instructions
executed by a processing unit, or by a combination thereof. The processing unit can comprise
a computer, a processor, such as the processor 108, a state machine, a logic array or any other
suitable devices capable of processing instructions. The processing unit can be a generalpurpose
processor which executes instructions to cause the general-purpose processor to
20 perform the tasks or, the processing unit can be dedicated to perform the functions.
[0034] In another aspect of the present subject matter, the modules 114 may be
machine-readable instructions (software) 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 or other machine-readable
25 storage medium or non-transitory medium. In one implementation, the machine-readable
instructions can be also be downloaded to the storage medium via a network connection. The
data 116 serves, amongst other things, as a repository for storing data that may be fetched,
processed, received, or generated by one or more of the modules 114.
[0035] In an implementation, each of the modules 114 includes the MEP 106 and
30 other modules. For example, network device 102-1 and the network device 102-2 include the
MEP 106-1, 106-2 and other module(s) 118-2, 118-2, respectively, collectively referred to as
the MEP 106 and the other module(s) 118. Further, each of the MEPs 106 includes a message
13
generation module, a networking module, and a processing module. For example, the
network device 102-1 includes a message generation module 120-1, a networking module
122-1, and a processing module 124-1; while the network device 102-2 includes a message
generation module 120-2, a networking module 122-2, and a processing module 124-2. The
message generation modules for all the network devices 102 are hereinafter collectivel5 y
referred to as the message generation module 120. The networking modules for all the
network devices 102 are hereinafter collectively referred to as the networking module 122
and similarly, the processing modules for all the network devices 102 are hereinafter
collectively referred to as the processing module 124.
10 [0036] Further, data 116 for each of the network devices 102 includes MEP data,
network data and other data. For example, network device 102-1 includes MEP data 126-1,
network data 128-1, and other data 130-1; while the network device 102-2 includes MEP data
126-2, network data 128-2, and other data 130-2. The MEP data for all the network devices
102 is hereinafter collectively referred to as the MEP data 126. The network data for all the
15 network devices 102 is hereinafter collectively referred to as the network data 128 and
similarly, the other data for all the network devices 102 is hereinafter collectively referred to
as the other data 130. The other data 130 comprise data corresponding to one or more other
module(s) 118.
[0037] According to an embodiment of the present subject matter, a first network
20 device, say the network device 102-1, having installed a first MEP, say, the MEP 106-1
intending to connect with other MEPs for implementing CFM may utilize a MEP discovery
mechanism to discover all MEPs that belong to the same maintenance association as that of
the first MEP 106-1. In order to initiate the MEP discovery mechanism, the message
generation module 120 of the first network device 102-1 may generate a loopback message
25 (LBM). In one implementation, the loopback message may include a common CFM header, a
LBM opcode, a loopback transaction identifier, an end type-length-value (TLV), and the
MAID corresponding to first MEP 106, i.e., the MAID of the maintenance association to
which the first MEP 106 belongs. As will be understood, the common CFM header, the LBM
opcode, the loopback transaction identifier, and the end type-length-value (TLV) are
30 conventional fields that are present in a loopback message conventionally exchanged between
the MEPs. In order to generate the loopback message, the message generation module 120
may initially access the MEP data 126-1 to obtain the MAID corresponding to first MEP 106
14
and subsequently generate the loopback message having the MAID. The message generation
module 120 may further save the loopback message in the network data 128-1.
[0038] The networking module 122 of the first network device 102-1 may
subsequently multicast the loopback message to all the other network devices 102 having
other MEPs 106 belonging to the same maintenance domain level as the first MEP 106. Fo5 r
instance, in case the MEP 106 residing in the first network device 102-1 is registered with a
MD level three, i.e., the service provider domain, then the networking module 122 may
multicast the loopback message such that it is received by all the network devices 102 having
MEPs 106 that are registered with the MD level three. In one example, let a second MEP,
10 say, the MEP 106-2 residing in the network devices 102-2 also be registered with the MD
level three. In such a case the networking module 122 of the network device 102-2,
interchangeably referred to as a second network device 102, may receive the loopback
message from the first network device 102.
[0039] Upon receiving the loopback message, the networking module 122 of the
15 network device 102-2 may save the loopback message in the networking data 128-2 of the
second network device 102. Subsequently, the processing module 124 of the second network
device 102 may obtain the loopback message and analyze the loopback message to determine
if the second MEP 106 and the first MEP 106 belong to the same maintenance association. In
one implementation, the processing module 124-2 may initially obtain the MAID
20 corresponding to the first MEP 106 from loopback message and the MAID assigned to the
second MEP 106 from the MEP data 126-2. The processing module 124-2 may then compare
the MAID received in the loopback message with the MAID assigned to it to determine
whether the first MEP 106 and the second MEP 106 share the same MAID. In case the MAID
received in the loopback message is same as the MAID assigned to the second MEP 106, the
25 processing module 124-2 may ascertain that the first MEP 106 belongs to the same
maintenance association as the second MEP 106.
[0040] Based on the above assertion, the message generation module 120-2 of the
network device 102-2 may generate a loopback reply (LBR) message having the MAID and a
MEPID corresponding to the second MEP 106. In one implementation, the LBR message
30 may include the common CFM header, the LBM opcode, the loopback transaction identifier,
the end TLV, the MEPID corresponding to the second MEP 106, and the MAID
15
corresponding to second MEP 106, i.e., the MAID of the maintenance association to which
the second MEP 106 and the first MEP 106 belongs. As will be understood, the common
CFM header, the LBM opcode, the loopback transaction identifier, and the end TLV are
conventional fields that are present in a LBR message conventionally exchanged between
MEPs. The message generation module 120-2 may further save the LBR message in th5 e
network data 128-2.
[0041] Further, the networking module 122-2 may transmit the LBR message to the
first network device 102-1 over the communication network 104 so that the first MEP 106
may use the MEPID of the second MEP 106 for exchanging connectivity fault management
10 messages for connectivity fault management. In one implementation, the networking module
122-1 may receive the LBR message from the networking module 122-2 and save the LBR
message in the MEP data 126 for further processing. The processing module 124-1, on
receiving the LBR message, may determine that the second MEP 106 installed in the network
device 102-2 belongs to the same maintenance association to which the first MEP 106
15 belongs. The first MEP 106 may thus ascertain the second MEP 106 as a remote MEP with
which the first MEP 106 may exchange connectivity fault management messages for
connectivity fault management. The processing module 124-1 may thus update an internal
MEP table stored in the MEP data 126-1 to include details of the second MEP 106 and in turn
the network device 102-2. The MEP table may be understood as an internal table having
20 MEPID and MAC address of the MEPs having the same MAID as the first MEP 106 that
may be used by the first MEP 106 to exchange CFM messages for connectivity fault
management. The processing module 124-1 may initially analyze the LBR message to obtain
the MEPID and a MAC address corresponding to the second MEP 106 and in turn the
network device 102-2.
25 [0042] The processing module 124-1 may then update the internal MEP table by
adding the MEPID and MAC address of the second MEP 106 and in turn the network device
102. The processing module 124-1 may further update a MEP database 132 coupled to the
network device 102 over the communication network 104. The MEP database 132 may be
understood as a common MEP database shared by the network devices 102 connected to the
30 communication network 104. In one implementation, the processing module 124 may update
the MEP database 132 periodically. In another implementation, the processing module 124
may update the MEP database 132 each time it discovers a new MEP.
16
[0043] Further, in one implementation, each time the processing module 124
discovers a new MEP 106, the processing module 124 compares the MEPID of the new MEP
106 with a MEPID of the first MEP 106 in order to determine whether the new MEP 106 and
the first MEP 106 have been assigned the same MEPID. For instance, on receiving the LBR
from the network device 102-2, the processing module 124 may compare the MEPID of th5 e
second MEP 106 with the MEPID of the first MEP 106 to ascertain whether the first MEP
106 and the second MEP have been assigned the same MEPID by mistake. In case the two
MEPs 106 have been assigned the same MEPID, the processing module 124 notifies a central
server (not shown in the figure) or a system administrator about an erroneous allocation of
10 the same MEPID to two MEPs 106 belonging to the same maintenance association. The
central server or the system administrator, in such a case, may take one or more predetermined
corrective measures to ensure that all MEPs 106 belonging to a single
maintenance association are assigned unique MEPIDs.
[0044] Figure 2 and 3 illustrate a method 200 and a method 300, respectively, for
15 discovery of maintenance end points for connectivity fault management, according to an
embodiment of the present subject matter. The order in which the method is described is not
intended to be construed as a limitation, and any number of the described method blocks can
be combined in any order to implement the methods 200 and 300 or any alternative methods.
Additionally, individual blocks may be deleted from the methods without departing from the
20 spirit and scope of the subject matter described herein. Furthermore, the method(s) can be
implemented in any suitable hardware, software, firmware, or combination thereof.
[0045] The method(s) 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
25 perform particular functions or implement particular abstract data types. The methods 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.
30 [0046] A person skilled in the art will readily recognize that steps of the method(s)
200 and 300 can be performed by programmed computers. Herein, some embodiments are
17
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 machineexecutable
or computer-executable 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 magneti5 c
tapes, hard drives, or optically readable digital data storage media. The embodiments are also
intended to cover both communication network and communication devices to perform said
steps of the method(s).
[0047] Figure 2 illustrates the method 200 a method for discovery of maintenance end
10 points for connectivity fault management, according to an embodiment of the present subject
matter.
[0048] At block 202, a loopback message is generated. In one implementation, the
loopback message is generated by a first maintenance end point (MEP), say the first MEP
106 of the network device 102. The first MEP intends to discover remote MEPs belonging to
15 the same maintenance association to which the first MEP belongs. The first MEP generates
the loopback message having a maintenance association identifier (MAID) corresponding to
the maintenance association to which the first MEP belongs. The loopback message may
include a common CFM header, a LBM opcode, a loopback transaction identifier, an end
type-length-value (TLV), and the MAID corresponding to first MEP 106, i.e., the MAID of
20 the maintenance association to which the first MEP 106 belongs.
[0049] At block 204, the loopback message is transmitted to one or more other MEPs.
In one implementation, the first MEP may transmit the loopback message as a multicast
message to the MEPs that are registered with a maintenance domain (MD) level with which
the first MEP is registered. For instance, in case the first MEP is registered with MD level
25 two, the loopback message may be multicast to all the MEPs that are registered with the MD
level two.
[0050] At block 206, a loopback reply (LBR) message is received from at least one
MEP from among the one or more other MEPs. In one implementation, upon receiving the
loopback message, the one or more other MEPs may analyze the loopback message to obtain
30 the MAID of the first MEP. The at least one MEP, having the same MAID as the first MEP,
may then generate and transmit the LBR message to the first MEP. The LBR message may
include the common CFM header, the LBM opcode, the loopback transaction identifier, the
18
end TLV, the MEPID corresponding to the second MEP 106, and the MAID corresponding to
second MEP 106, i.e., the MAID of the maintenance association to which the second MEP
106 and the first MEP 106 belongs.
[0051] At block 208, LBR message is analyzed to obtain a MEP identifier (MEPID)
corresponding to the at least one MEP. Upon receiving the LBR message, the first MEP ma5 y
ascertain that the at least one MEP and the first MEP belong to the same maintenance
association. The first MEP may thus determine that the at least one MEP is a remote MEP
with which the first MEP may exchange connectivity fault management messages for
connectivity fault management. The first MEP may then obtain the MEPID of the at least one
10 MEP for interacting with the MEP.
[0052] At block 210, a MEP database is updated using the MEPID of the at least one
MEP. In one implementation, the first MEP may initially update an internal MEP table
having MEPID and MAC address of the MEPs having the same MAID as the first MEP.
Once updated, the first MEP may access the internal MEP or the MEP database to determine
15 the MEPID and the MAC address of all the MEPs to which it may send CFM messages for
connectivity fault management.
[0053] Figure 3 illustrates a method 300 a method for discovery of maintenance end
points for connectivity fault management, according to an embodiment of the present subject
matter.
20 [0054] At block 302, a loopback message is received. In one implementation, the
loopback message is received by a first maintenance end point (MEP), say the first MEP 106
of the network device 102-1 from a second MEP, say the second MEP 106 of the network
device 102-2.
[0055] At block 304, the loopback message is analyzed to obtain a maintenance
25 association identifier (MAID). In one implementation, the MAID corresponds to a
maintenance association to which the second MEP belongs.
[0056] At block 306, a determination is made to ascertain whether the MAID of the
second MEP is same as a MAID of the first MEP or not. If the MAID of the second MEP is
different from the MAID of the first MEP, which is the 'No' path from the block 306, the
30 method moves to the block 308 where the first MEP may ignore the loopback message.
19
[0057] In case at block 306, it is determined that the MAID of the second MEP is
same as the MAID of the first MEP, which is the 'Yes' path from the block 306, the second
MEP is determined to belong to the same maintenance association with which the first MEP
is registered at block 310.
[0058] At block 312, a loopback reply (LBR) message is generated. In on5 e
implementation, the LBR message may include a common CFM header, a LBM opcode, a
loopback transaction identifier, an end TLV, the MEPID corresponding to the second MEP
106, and the MAID corresponding to first MEP 106, i.e., the MAID of the maintenance
association to which the first MEP 106 and the first MEP 106 belong.
10 [0059] At block 314, the LBR message is transmitted to the second MEP. In one
implementation, the first MEP may transmit the LBR message to the second MEP so that the
second MEP may use the MEPID of the first MEP for exchanging connectivity fault
management messages for connectivity fault management.
[0060] Although embodiments for the present subject matter have been described in a
15 language specific to structural features or method(s), it is to be understood that the invention
is not necessarily limited to the specific features or method(s) described. Rather, the specific
features and methods are disclosed as embodiments for the present subject matter.
20

I/We claim:
1. A method for discovering maintenance end points in a communication network (104)
for connectivity fault management within the communication network (104), the method
comprising:
generating, by a first maintenance end point (MEP) (106-1), a loopback messag5 e
having a maintenance association identifier (MAID) corresponding to a maintenance
association to which the first MEP (106-1) belongs;
multicasting, by the first MEP (106-1), the loopback message to one or more other
MEPs (106) registered with a maintenance domain (MD) level with which the first MEP
10 (106-1) is registered;
receiving, by the first MEP (106-1), a loopback reply message from at least one other
MEP (106) from among the one or more other MEPs (106), wherein the at least one other
MEP (106) has the same MAID as the first MEP (106-1); and
determining, by the first MEP (106-1), the at least one other MEP (106-2) to belong to
15 the same maintenance association to which the first MEP (106-1) belongs based on the
receiving, wherein the at least one MEP (106-1) is ascertained as a remote MEP with which
the first MEP (106-1) exchanges connectivity fault management messages for connectivity
fault management.
2. The method as claimed in claim 1 further comprising:
20 analyzing, based on the determining, the loopback reply message to obtain a MEP
identifier (MEPID) corresponding to the at least one other MEP (106-2); and
updating a MEP database (132) using at least the MEPID of the at least one MEP
(106).
3. The method as claimed in claim 2, wherein the analyzing further comprises obtaining
25 a media access control (MAC) address of the at least one other MEP (106-2) based on
loopback reply message.
4. The method as claimed in claim 1 further comprising:
comparing, based on the determination by the first MEP (106-1), the MEPID of the at
least one other MEP (106-2) with a MEPID of the first MEP (106-1) to determine whether
30 the at least one other MEP (106-2) and the first MEP (106-1) have the same MEPID; and
notifying, by the first MEP (106), a central server about an erroneous allocation of the
same MEPID to the first MEP (106-1) and the at least one other MEP (106-2) belonging to
the same maintenance association.
21
5. A network device (102) implementing a first maintenance end point (MEP) (106-1)
comprising:
a processor (108);
a message generation module (120) coupled to the processor (108) to generate a
loopback message having a maintenance association identifier (MAID) corresponding to 5 a
maintenance association to which the first MEP (106-1) belongs;
a networking module (122) coupled to the processor (108) to:
multicast the loopback message to one or more other network devices (102-2),
wherein each of the one or more network devices (102) implements a MEP (106)
10 registered with a maintenance domain (MD) level with which the first MEP (106-1) is
registered; and
receive a loopback reply message from at least one other network device (102)
from among the one or more other network devices (102), wherein the at least one
network device (102) implements a second MEP (106-2) having the same MAID as
15 the first MEP (106-1); and
a processing module (124) coupled to the processor (108) to determine, based on the
receiving, the second MEP (106-2) to belong to the same maintenance association to which
the first MEP (106-1) belongs, wherein the second MEP (106-2) is ascertained as a remote
MEP with which the first MEP (106-1) exchanges connectivity fault management messages
20 for connectivity fault management.
6. The network device (102) as claimed in claim 5, wherein the processing module (124)
further:
analyzes the loopback reply message to obtain a MEP identifier (MEPID)
corresponding to the second MEP (106-2); and
25 updates a MEP database (132) using at least the MEPID of the second MEP (106-2).
7. The network device (102) as claimed in claim 5, wherein the processing module (124)
further:
compares the MEPID of the second MEP (106-2) with a MEPID of the first MEP
(106-1) to determine whether the second MEP (106-2) and the first MEP (106-1) have the
30 same MEPID; and
notifies a central server about an erroneous allocation of the same MEPID to the first
MEP (106-1) and the second MEP (106-2).
22
8. A method for discovering maintenance end points in a communication network for
connectivity fault management within the communication network, the method comprising:
analyzing, by a first maintenance end point (MEP) (106-1), a loopback message
received from a second MEP (106-2) to obtain a maintenance association identifier (MAID)
corresponding to a maintenance association to which the second MEP (106-2) belongs5 ;
comparing the MAID of the second MEP (106-2) with a MAID of the first MEP (106-
1) to determine if the second MEP (106-2) and the first MEP (106-1) belong to the same
maintenance association; and
transmitting, by the first MEP (106-1), a loopback reply (LBR) message to the second
10 MEP (106-2) based on the determination, wherein the LBR message includes a MEPID of the
first MEP (106-1), wherein the MEPID of the first MEP (106-2) is used by the second MEP
(106-2) for exchanging connectivity fault management messages for connectivity fault
management.
9. The method as claimed in claim 8 further comprising receiving, by the first MEP
15 (106-1), the loopback message from the second MEP (106-2) as a multicast message.
10. The method as claimed in claim 8, wherein the transmitting comprises generating the
LBR message having the MEPID and the MAID corresponding to the second MEP (106-2).
11. A network device (102) implementing a first maintenance end point (MEP) (106-1)
comprising:
20 a processor (108);
a processing module (124) coupled to the processor (108) to:
analyze a loopback message received from a second network device (102-2)
implementing a second MEP (106-2) to obtain a maintenance association identifier
(MAID) corresponding to a maintenance association to which the second MEP (106-
25 2) belongs; and
compare the MAID of the second MEP (106-2) with a MAID of the first MEP
(106-1) to determine if the second MEP (106-2) and the first MEP (106-1) belong to
the same maintenance association; and
a networking module (122) coupled to the processor (108) to:
30 transmit a loopback reply (LBR) message to the second network device (102-
2) based on the determination, wherein the LBR message includes a MEPID of the
first MEP (106-1), wherein the MEPID of the first MEP (106-1) is used by the second
23
MEP (106-2) for exchanging connectivity fault management messages for
connectivity fault management.
12. The network device (102) as claimed in claim 11, wherein the network device (102)
further includes a message generation module (120) coupled to the processor (108) to
generate the LBR message having the MEPID and the MAID corresponding to the secon5 d
MEP (106-2).
13. The network device (102) as claimed in claim 11, wherein the networking module
(122) receives the loopback message as a multicast message from the second network device
(102-2).
10 14. A non-transitory computer-readable medium having embodied thereon a computer
program for executing a method for discovering maintenance end points in a communication
network for connectivity fault management within the communication network, the method
comprising:
generating, by a first maintenance end point (MEP) (106-1), a loopback message
15 having a maintenance association identifier (MAID) corresponding to a maintenance
association to which the first MEP (106-1) belongs;
multicasting, by the first MEP (106-1), the loopback message to one or more other
MEPs (106) registered with a maintenance domain (MD) level with which the first MEP
(106-1) is registered;
20 receiving, by the first MEP (106-1), a loopback reply message from at least one other
MEP (106-2) from among the one or more other MEPs (106), wherein the at least one other
MEP (106-2) has the same MAID as the first MEP (106-1); and
determining, by the first MEP (106-1), the at least one other MEP (106-2) to belong to
the same maintenance association to which the first MEP (106-1) belongs based on the
25 receiving, wherein the first MEP (106-1) is ascertained as a remote MEP with which the first
MEP (106-1) exchanges connectivity fault management messages for connectivity fault
management.
15. A non-transitory computer-readable medium having embodied thereon a computer
program for executing a method for discovering maintenance end points in a communication
30 network for connectivity fault management within the communication network, the method
comprising:
24
analyzing, by a first maintenance end point (MEP) (106-1), a loopback message
received from a second MEP (106-2) to obtain a maintenance association identifier (MAID)
corresponding to a maintenance association to which the second MEP (106-2) belongs;
comparing the MAID of the second MEP (106-2) with a MAID of the first MEP (106-
1) to determine if the second MEP (106-2) and the first MEP (106-1) belong to the sam5 e
maintenance association; and
transmitting, by the first MEP (106-1), a loopback reply (LBR) message to the second
MEP (106-2) based on the determination, wherein the LBR message includes a MEPID of the
first MEP (106-1), wherein the MEPID of the first MEP (106-1) is used by the second MEP
10 (106-2) for exchanging connectivity fault management messages for connectivity fault
management.
15 Date 15 January 2014
JAYA PANDEYA
IN/PA-1345
Agent for the Applicant
20 To,
The Controller of Patents
The Patent Office at New Delhi