FIELD OF INVENTION
[0001] The present subject matter relates to communication between fibre
channel (FC) switches and, particularly, but not exclusively, to establishing 5 a
connection between FC switches.
BACKGROUND
[0002] Storage area networks (SANs) are deployed in enterprises, educational
institutions, data centers, and government institutions for efficient storage and
10 communication of data. Such SANs, typically, implement Fibre Channel (FC)
technology for facilitating high speed data transmission between network elements,
such as storage devices, databases, tape disks, hubs, and servers present in the SANs.
In order to interconnect the network elements present in a SAN, FC switches, i.e.,
switches compatible with the FC technology are deployed in the SAN. The FC
15 switches facilitate in establishing a connection between the network elements for
communication of data and management of network traffic amongst the network
elements.
SUMMARY
[0003] This summary is provided to introduce concepts related to
20 communication between Fibre Channel (FC) switches. This summary is not intended
to identify essential features of the claimed subject matter nor is it intended for use in
determining or limiting the scope of the claimed subject matter.
[0004] In one implementation, a method for establishing a connection
between FC switches is disclosed. The method comprises, receiving, by a relay
25 system, an Exchange Link Parameters (ELP) packet from a first Fibre Channel (FC)
switch, where the first FC switch is connected to the relay system through a first
3
Expansion Port (E_Port) of the relay system. The method further comprises
determining the ELP packet to be indicative of a request to establish a connection
between the first FC switch and a second FC switch, where the second FC switch is
connected to the relay system through a second E_Port of the relay system. Further,
an updated ELP packet is transmitted to the second FC switch through the secon5 d
E_Port for facilitating establishment of the connection, where the updated ELP packet
comprises at least one parameter corresponding to the second E_Port. The method
further comprises receiving, from the second FC switch, a connection establishment
response message responsive to the transmitting the updated ELP packet, where the
10 connection establishment request indicates one of an acceptance and rejection to
establish the connection. Further, an updated connection establishment message is
transmitted to the first FC switch through the first E_Port for establishing the
connection between the first FC switch and the second FC switch, where the updated
connection establishment message comprises at least one parameter corresponding to
15 the first E_Port.
[0005] In another implementation, a relay system is disclosed. The gateway
includes a processor and a packet update module coupled to the processor. In an
implementation, the packet update module receives an Exchange Link Parameters
(ELP) packet from a first Fibre Channel (FC) switch, where the first FC switch is
20 connected to the relay system through a first Expansion Port (E_Port) of the relay
system. The packet update module further determines the ELP packet to be indicative
of a request to establish a connection between the first FC switch and a second FC
switch, where the second FC switch is connected to the relay system through a
second E_Port of the relay system. The packet update module further transmits an
25 updated ELP packet to the second FC switch through the second E_Port for
facilitating establishment of the connection, where the updated ELP packet comprises
at least one parameter corresponding to the second E_Port. The packet update module
further receives from the second FC switch, a connection establishment response
4
message responsive to the transmitting the updated ELP packet, where the connection
establishment request indicates one of an acceptance and rejection to establish the
connection. The packet update module further transmits an updated connection
establishment message to the first FC switch through the first E_Port for establishing
the connection between the first FC switch and the second FC switch, where th5 e
updated connection establishment message comprises at least one parameter
corresponding to the first E_Port.
[0006] In accordance with another implementation of the present subject
matter, a non-transitory computer-readable medium having embodied thereon a
10 computer program for executing a method is disclosed. The method comprises,
receiving, by a relay system, an Exchange Link Parameters (ELP) packet from a first
Fibre Channel (FC) switch, where the first FC switch is connected to the relay system
through a first Expansion Port (E_Port) of the relay system. The method further
comprises determining the ELP packet to be indicative of a request to establish a
15 connection between the first FC switch and a second FC switch, where the second FC
switch is connected to the relay system through a second E_Port of the relay system.
Further, an updated ELP packet is transmitted to the second FC switch through the
second E_Port for facilitating establishment of the connection, where the updated
ELP packet comprises at least one parameter corresponding to the second E_Port.
20 The method further comprises receiving, from the second FC switch, a connection
establishment response message responsive to the transmitting the updated ELP
packet, where the connection establishment request indicates one of an acceptance
and rejection to establish the connection. Further, an updated connection
establishment message is transmitted to the first FC switch through the first E_Port
25 for establishing the connection between the first FC switch and the second FC switch,
where the updated connection establishment message comprises at least one
parameter corresponding to the first E_Port.
BRIEF DESCRIPTION OF THE FIGURES
5
[0007] The detailed description is provided with reference to the
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
embodiments of system and/or methods in accordance with embodiments of th5 e
present subject matter are now described, by way of example only, and with reference
to the accompanying figures, in which:
[0008] Figure 1 illustrates an exemplary network environment
implementation for establishing a connection between FC switches, according to an
10 embodiment of the present subject matter;
[0009] Figure 2(a) illustrates a call flow diagram for establishing a connection
between FC switches, according to an embodiment of the present subject matter;
[0010] Figure 2(b) illustrates components of a relay system for establishing a
connection between FC switches, according to an embodiment of the present subject
15 matter; and
[0011] Figure 3 illustrates a method for establishing a connection between FC
switches, according to an embodiment of the present subject matter.
DESCRIPTION OF EMBODIMENTS
[0012] A storage area network (SAN) comprises several network elements,
20 such as servers, databases, and storage devices interconnected with each other
through a plurality of Fibre Channel (FC) switches deployed in the SAN. An FC
switch may be understood as a switch compatible with FC technology implemented
in the SAN for facilitating high speed data transmission amongst the network
elements. As may be understood, for facilitating communication between the network
25 elements, the FC switches present in the SAN are also interconnected via optical fibre
cables. For example, a first FC switch connected to a first set of network elements
may be connected to a second FC switch connected to another set of network
6
elements. Thus, the interconnected FC switches render support for communication
amongst the network elements present in the aforementioned sets of network
elements.
[0013] Typically, there exists a point-to-point connection between each pair
of FC switches present in the SAN. In certain cases, owing to the complexit5 y
associated with deployment, management, and maintenance of the optical fibre
cables, interconnecting the FC switches proves to be a cumbersome task. For
example, in a SAN network having a large number of FC switches, establishing a
point-to-point connection between the FC switches may prove to be a cumbersome
10 task. Moreover, in cases where the FC switches are distantly located, for example, in
different buildings or at different floors of a building, extensive cable may be
deployed for interconnecting the FC switches. As a result, overall cost associated
with interconnection of the FC switches may increase.
[0014] The present subject matter describes systems and methods for
15 establishing a connection between FC switches. In accordance with the present
subject matter, a relay system comprising a plurality of Expansion Ports (E_Ports) for
facilitating establishment of the connection between the FC switches is described. In
an implementation, the FC switches to be interconnected are connected to the relay
system through the E_Ports.
20 [0015] In an implementation, a connection between two FC switches, say, a
first FC switch and a second FC switch is achieved using the relay system. For
example, the first FC switch may be connected to a first E_Port of the FC switch and
the second FC switch may be connected to a second E_Port of the relay system. As
may be understood, in order to establish the connection, one or more control packets
25 based on an Exchange Link Parameters (ELP) protocol are exchanged between the
two FC switches. In said implementation, the relay system facilitates the
establishment of the connection by tunneling the control packets received from the
first FC switch to the second FC switch and vice-versa.
7
[0016] In operation, the relay system may receive an ELP packet from the
first FC switch. The ELP packet may be understood as a control packet used for
initiating establishment of a connection between FC switches based on the ELP
protocol. In said example, based on the contents of the ELP packet, the relay system
may determine the ELP packet to be indicative of a request for establishing th5 e
connection between the first FC switch and the second FC switch. The ELP packet
further comprises one or more parameters corresponding to a port of the first FC
switch from which the ELP packet was transmitted. As may be understood, the
parameters correspond to a port through which they are transmitted and indicate a
10 capacity of the port to handle network traffic in accordance with a known flow
control mechanism. The flow control mechanism is typically implemented for
ensuring guaranteed delivery of control packets and data packets between the FC
switches. The ELP packet may then be transmitted to the second FC switch.
[0017] As mentioned previously, the second FC switch is connected to the
15 relay system through the second E_Port. Thus, prior to transmittal of the ELP packet,
in an implementation, the parameters of the ELP packet may be modified in a manner
such that at least one parameter, from among the parameters, corresponds to the
second E_Port. For example, an initial value, corresponding to the port of the first FC
switch, of the at least one parameter may be replaced with a value corresponding to
20 the second E_Port. As a result, an updated ELP frame may be obtained. Thereafter,
the updated ELP frame is transmitted to the second FC switch through the second
E_Port for facilitating establishment of the connection.
[0018] Upon receiving the updated ELP packet, the second FC switch may
transmit a connection establishment response message to the relay system. In an
25 example, the connection establishment response message may indicate whether the
second FC switch has accepted/ rejected the request for establishment of the
connection. For instance, in a case where the second FC switch may agree to establish
the connection, the connection establishment response message may be a SW_ACC
8
message. As may be understood, the SW_ACC message indicates an acceptance to
establish the connection. Further, the connection establishment response message
may also include one or more parameters corresponding to a port of the second FC
switch through which the connection establishment response message is transmitted.
[0019] In an example, upon receiving the connection establishment respons5 e
message, the one or more parameters of the connection establishment response
message may be modified in a manner as described above in reference to the
modified ELP frame to obtain an updated connection establishment response
message. In said example, at least one parameter of the updated connection
10 establishment response message corresponds to the first E_Port. The updated
connection establishment response message may then be transmitted to the first FC
switch for establishment of the connection. Once the connection is established, data
packets may be exchanged between the first FC switch and the second FC switch
over the connection.
15 [0020] Thus, the relay system facilitates in establishing a connection between
the two switches. As may be understood from the foregoing description, the relay
system provides for a centric solution for interconnecting the FC switches. Thus,
interlinking of the FC ports via a point-to-point optical fibre connection is averted. As
a result, the complexity associated with deployment, management, and maintenance
20 of the optical fibre cable is reduced. Further, the relay system, as described herein,
facilitates establishment of the connection in accordance with the existing flow
control mechanisms. Thus, the present subject matter provides a less complex
approach for interconnecting FC switches without addition of any computational
overheads.
25 [0021] 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
9
are included within its spirit and scope. Further, all examples recited herein are
principally intended expressly to be only 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 be construed as being
without limitation to such specifically recited examples and conditions. Moreover, al5 l
statements herein reciting principles, aspects, and embodiments of the present subject
matter, as well as specific examples thereof, are intended to encompass equivalents
thereof.
[0022] The manner in which the systems and the methods for communication
10 between FC switches shall be implemented has been explained in details with respect
to the Figures 1, 2(a), 2(b), and 3. While aspects of described systems and methods
for communication between FC switches can be implemented in any number of
different computing systems, transmission environments, and/or configurations, the
embodiments are described in the context of the following exemplary system(s).
15 [0023] Figure 1 illustrates a network environment 100 for establishing a
connection between FC switches. The network environment 100 includes a relay
system 102 comprising a plurality of E_Ports 104-1, 104-2, 104-3, 104-4, 104-5, ....,
104-N, hereinafter collectively referred to as E_Ports 104 and individually referred to
as E_Port 104. In an implementation, the relay system 102 may comprise one or more
20 relay devices not shown in the figure for the sake of brevity. In said implementation,
each of the relay device may comprise one or more of the E_ports 104.
[0024] The E_Ports 104 facilitate a plurality of FC switches 106-1, 106-2,
106-3, ...., 106-N, hereinafter collectively referred to as FC switches 106 and
individually referred to as FC switch 106, to connect to the relay system 102. In an
25 example, the FC switches 106 may pertain to a single Storage Area Network (SAN).
In another example, the FC switches 106 may pertain to different SANs. The FC
switches 106 interconnect storage devices (not shown) and processing devices (not
shown) present in the SAN/SANs.
10
[0025] In an implementation, the relay system 102 may be configured to
facilitate interconnection of the FC switches 102. For example, the relay system 102
may be configured to facilitate establishment of a connection between the FC switch
106-1 and the FC switch 106-3. In said example, as shown in the figure, the FC
switch 106-1 is connected to the relay system 102 through the E_Port 104-1 and th5 e
FC switch 106-3 is connected to the relay system 102 through the E_Port 104-4. As
may be understood, the connection between the FC switches 102 and the relay system
102 may be connected via fibre optical cables.
[0026] In an example, the FC switches 102 may establish the connection
10 based on an ELP protocol. Thus, in accordance with the ELP protocol, the FC switch
106-1 and the FC switch 106-3 may seek to exchange one or more control packets,
for example, an ELP packet, with each other for establishment of the connection. In
an implementation, the relay system 102 may be configured to transmit the control
packets received from the FC switch 106-1 to the FC switch 106-3.
15 [0027] Fig. 2(a) illustrates a call-flow diagram indicating a procedure for
establishing a connection between the FC switches, in accordance with an
embodiment of the present subject matter. The various arrow indicators used in the
call-flow diagram depict the transfer of signal/information between the FC switch
106-1, the relay system 102, and the FC switch 106-3. For the sake of brevity, the
20 description of Figure 2(a) has been described below in conjunction with description
of Figure 1.
[0028] In operation, the relay system 102 may receive an ELP packet 202
from the FC switch 106-1 through the E_Port 104-1. The relay system 102 may then
determine the ELP packet 202 to be indicative of a request to establish the connection
25 between the FC switch 106-1 and the FC switch 106-3. Based on the determination,
the relay system 102 may subsequently seek to transmit the ELP packet 202 to the FC
switch 106-3 for facilitating establishment of the connection.
11
[0029] Prior to transmittal of the ELP packet 202, the relay system 102 may
update the ELP packet to obtain an updated ELP packet 204. In an example, the
updated ELP packet 204 may comprise at least one parameter corresponding to the
E_Port 104-4. As may be understood, the at least one parameter corresponds to a port
through which the ELP packet is transmitted. For example, the relay system 102 ma5 y
replace an initial value of BB_Credits and BB_SC-N parameters of the ELP packet
with a value corresponding to the E_Port 104-4. As may be understood, the initial
value of the BB_Credits and BB_SC-N parameter may correspond to a port of the FC
switch 106-1. The relay system 102 may subsequently transmit the updated ELP
10 packet 204 to the FC switch 106-3 through the E_Port 104-4.
[0030] Upon receiving the updated ELP packet 204, the FC switch 106-3 may
transmit an acknowledgement (ACK) message, such as the ACK-1 206 to the first FC
switch 106-1 to indicate successful reception of the updated ELP packet 204. In an
example, the relay system 102 may receive the ACK-1 206 and may subsequently
15 transmit the ACK-1 206 to the first FC switch 106-1.
[0031] In an implementation, the relay system 102 may receive a connection
establishment response message 208 from the FC switch 106-3 through the E_Port
104-4. The connection establishment response message 208 indicates whether the FC
switch 106-3 has accepted/rejected the request to establish the connection with the FC
20 switch 106-1. For example, in a case where the FC switch 106-3 ascertains to
establish the connection, the connection establishment response message 208 may
include an SW_ACC packet. In another case where the FC switch 106-3 ascertains
not to establish the connection, the connection establishment response message 208
may include an SW_RJT packet.
25 [0032] The relay system 102 may subsequently seek to transmit the
connection establishment response message 208 to the FC switch 106-1. In an
implementation, prior to the transmission of the connection establishment response
message 208, the relay system 102 may update an initial value of at least one
12
parameter of the connection establishment response message 208 to obtain an
updated connection establishment response message 210. In said implementation, a
value of the at least one parameter of the updated connection establishment response
message 210 corresponds to the E_Port 104-1. The relay system 102 may
subsequently transmit the updated connection establishment response message 210 t5 o
the FC switch 106-1 through the E_Port 104-1 for establishment of the connection
between the FC switch 106-1 and the FC switch 106-3.
[0033] Upon receiving the updated connection establishment response
message 210, the FC switch 106-1 may transmit an acknowledgment message, say,
10 ACK-2 212, to the FC switch 106-3. The ACK-2 may be similar to the
acknowledgement message sent by the FC switch 106-3 and may indicate a
successful reception of the updated connection establishment response message 210.
The ACK-2 212 may be received by the relay system 102 and may subsequently be
transmitted to the FC switch 106-3.
15 [0034] Based on the updated connection establishment response message 210,
the FC switch 106-1 may then establish the connection with the FC switch 106-3.
Subsequently, data packets between the FC switch 106-1 and the FC switch 106-3
may be exchanged over the connection.
[0035] Figure 2(b) illustrates components of a relay system, such as the relay
20 system 102, for establishing a connection between FC switches, according to an
embodiment of the present subject matter.
[0036] In an implementation, the relay system 102 includes one or more
processor(s) 214, I/O interface(s) 216, and a memory 218 coupled to the processor(s)
214. The processor(s) 214 may be implemented as one or more microprocessors,
25 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) 214 are
13
configured to fetch and execute computer-readable instructions stored in the memory
218.
[0037] The functions of the various elements shown in the figures, 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 associatio5 n
with appropriate software. When provided by a processor, the functions may be
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
10 capable of executing software, and may implicitly include, without limitation, digital
signal processor (DSP) hardware, network processor, 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 custom, may also be included.
15 [0038] The I/O interface(s) 216 may include a variety of software and
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, etc.
Such interfaces facilitate the relay system 102 to communicate with the FC switches
106. Further, in an example, the I/O device(s) may include Universal Serial Bus
20 (USB) ports, Ethernet ports, host bus adaptors, etc., and their corresponding device
drivers.
[0039] The memory 218 may include any computer-readable medium known
in the art including, for example, volatile memory, such as static random access
memory (SRAM) and dynamic random access memory (DRAM), and/or non-volatile
25 memory, such as read only memory (ROM), erasable programmable ROM, flash
memories, hard disks, optical disks, and magnetic tapes.
14
[0040] The relay system 102 may also include various module(s) 220. The
module(s) 220, amongst other things, include routines, programs, objects,
components, data structures, etc., which perform particular tasks or implement
particular abstract data types. The module(s) 220 may also be implemented as, signal
processor(s), state machine(s), logic circuitries, and/or any other device or componen5 t
that manipulate signals based on operational instructions.
[0041] Further, the module(s) 220 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(s) 214, a
10 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 required tasks or,
the processing unit can be dedicated to perform the required functions.
[0042] In another aspect of the present subject matter, the module(s) 220 may
15 be machine-readable instructions (software) which, when executed by a
processor/processing unit, perform any of the described functionalities. The machinereadable
instructions may be stored on an electronic memory device, hard disk,
optical disk or other machine-readable storage medium or non-transitory medium. In
one implementation, the machine-readable instructions can be also be downloaded to
20 the storage medium via a network connection.
[0043] The module(s) 220 further includes a packet update module 224 and
other module(s) 226. The other module(s) 226 may include programs or coded
instructions that supplement applications and functions of the relay system 102. The
relay system 102 may further include data 222, which amongst other things, serves as
25 a repository for storing data processed, received, associated, and generated by one or
more of the module(s) 220. The data 222 includes, for example, port data 228 and
other data 230. The other data 230 includes data generated as a result of the execution
of one or more modules in the other module(s) 226.
15
[0044] In an implementation, the relay system 102 may be configured for
facilitating establishment of a connection between two FC switches, say, a first FC
switch and a second FC switch. In said implementation, the first FC switch may be
connected to the relay system through a first E_Port (not shown in figure). Similarly,
the second FC switch may be connected to the relay system 102 through a secon5 d
E_Port (not shown in figure).
[0045] In operation, the packet update module 224 may receive an ELP
packet from the first FC switch. The packet update module 224 may then analyze the
contents of the ELP packet to determine the ELP packet to be indicative of a request
10 to establish the connection with the second FC switch. Based on the determining, the
packet update module 224 may consume, i.e., store the ELP packet in an internal
memory (not shown) of the relay system 102.
[0046] Thereafter, the packet update module 224 may seek to transmit the
ELP packet to the second FC switch. As mentioned previously, one or more
15 parameters of the ELP packet may correspond to a port through which the ELP
packet is transmitted. Thus, the packet update module 224, prior to transmitting the
ELP packet, may replace an initial value of at least one parameter of the ELP packet
with a value corresponding to the second E_Port to obtain an updated ELP packet. As
may be understood, the initial value of the at least one parameter may correspond to a
20 port of the first FC switch through which the ELP packet was transmitted by the first
FC switch. In an example, the packet update module 224 may replace an initial value
of BB_Credits and BB_SC-N parameters of the ELP packet. The BB_Credits and
BB_SC-N parameters correspond to a port through which the ELP packet is
transmitted. Subsequently, the packet update module 224 may transmit the updated
25 ELP frame to the second FC switch through the second E_Port.
[0047] Upon receiving the ELP packet, the second FC switch may transmit an
acknowledgement (ACK) packet to indicate a successful reception of the updated
ELP frame to the first FC switch. The packet update module 224 may receive the
16
ACK message and may subsequently transmit the ACK message to the first FC
switch. Subsequently, the second FC switch may either accept or reject the request
for establishing the connection and may transmit a connection establishment response
message to the first FC switch. The connection establishment response message may
indicate one of an acceptance and rejection to establish the connection5 .
[0048] In an implementation, the packet update module 224 may receive the
connection establishment response message from the second FC switch. In a case
where the second FC switch ascertains to establish the connection, the connection
establishment response message may include an SW_ACC packet. In another case
10 where the second FC switch ascertains not to establish the connection, the connection
establishment response message may include an SW_RJT packet. In an example, the
packet update module 224 may also consume the connection establishment response
message.
[0049] Thereafter, the packet update module 224 may seek to transmit the
15 connection establishment response message to the first FC switch. In an
implementation, prior to transmitting the connection establishment response message,
the packet update module 224 may modify the connection establishment response
message to obtain an updated connection establishment response message. The
updated connection establishment response message comprises at least one parameter
20 corresponding to the first E_Port. As may be understood, the at least one parameter
includes a value corresponding to the first E_Port. In an example, the value
corresponding to the first E_Port and the second E_Port may be stored in the port
data 228.
[0050] The packet update module 224 may subsequently transmit the update
25 connection establishment response message to the first FC switch. Upon receiving the
updated connection establishment response message, the first FC switch may transmit
an ACK message to the second FC switch for indicating successful reception of the
updated connection establishment response message. Further, in the case where the
17
updated connection establishment response message includes the SW_ACC packet,
the first FC switch may then establish the connection with the second FC switch.
Subsequently, data packets may be exchanged between the first FC switch and the
second FC switch over the connection.
[0051] Figure 3 illustrates a method 300 for establishing a connectio5 n
between FC switches, in accordance with an embodiment of the present subject
matter. The order in which the method 300 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 method 300, or an alternative method.
10 Additionally, individual blocks may be deleted from the method without departing
from the spirit and scope of the subject matter described herein. Furthermore, the
method can be implemented in any suitable hardware, software, firmware, or
combination thereof.
[0052] The method(s) may be described in the general context of computer
15 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 data
types. The method may also be practiced in a distributed computing environment
where functions are performed by remote processing devices that are linked through a
20 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.
[0053] A person skilled in the art will readily recognize that steps of the
method 300 can be performed by programmed computers. Herein, some
25 embodiments are also intended to cover program storage devices, for example, digital
data storage media, which are machine or computer readable and encode machineexecutable
or computer-executable programs of instructions, wherein said
instructions perform some or all of the steps of the described method. The program
18
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 embodiments are also intended to cover all the communication
networks and communication devices configured to perform said steps of the
exemplary method5 .
[0054] At block 302, an ELP packet indicative of a request for establishing a
connection with a second switch is received from a first switch. In an example, a
relay system may receive the ELP packet from the first FC switch. In said example,
the first FC switch may be connected to the relay system through a first E_Port of the
10 relay system. Similarly, the second FC switch may be connected to the relay system
through a second E_Port of the relay system. Upon receiving the ELP packet, the
relay system may analyze the ELP packet and may determine the ELP packet to be
indicative of the request for establishing the connection between the first FC switch
and the second FC switch. In an implementation, the packet update module 224 of the
15 relay system 102 may receive the ELP packet 202 from the FC switch 106-1.
[0055] At block 304, an initial value of at least one parameter of the ELP
packet is replaced to obtain an updated ELP packet. The initial value may correspond
to a port of the first FC switch through which the ELP packet was transmitted. In an
example, the initial value may be replaced by a value corresponding to the second
20 E_Port to obtain the updated ELP packet. In an implementation, the packet update
module 224 may modify the ELP packet 202 to obtain the updated ELP packet 204.
[0056] At block 306, the updated ELP packet is transmitted to the second FC
switch. In an example, the update ELP packet is transmitted to the second FC switch
through the second E_Port of the relay system. For example, the E_Port 104-4 may
25 transmit the updated ELP packet 204 to the FC switch 106-3.
[0057] At block 308, a connection establishment response message
responsive to the updated ELP packet is received from the second FC switch. The
19
connection establishment response message indicates one of an acceptance and
rejection to establish the connection. In an example, the E_Port 104-4 may receive
the connection establishment response message 208 from the FC switch 106-3.
[0058] At block 310, an initial value of at least one parameter of the
connection establishment response message is replaced to obtain an update5 d
connection establishment response message. The initial value of the at least one
parameter may correspond to a port of the second FC switch through which the
connection establishment response message was transmitted. In an example, the
initial value may be replaced by a value corresponding to the first E_Port to obtain
10 the updated connection establishment response message. In an implementation, the
packet update module 224 may modify the connection establishment response
message 206 to obtain the updated connection establishment response message 208.
[0059] At block 312, the updated connection establishment response message
is transmitted to the first FC switch for establishing the connection between the first
15 FC switch and the second FC switch. In an example, the updated connection
establishment response message may be transmitted through the first E_Port. For
example, the E_Port 104-1 may transmit the updated connection establishment
response message 208 to the FC switch 106-1. In a case where, the updated
connection establishment response message indicates an acceptance to establish the
20 connection, the first FC switch may establish the connection with the second FC
switch. Thereafter, data packets may be exchanged between the first FC switch and
the second FC switch over the connection.
[0060] Although implementations for communication between FC switches
have been described in a language specific to structural features and/or methods, it is
25 to be understood that the appended claims are not necessarily limited to the specific
features or methods described. Rather, the specific features and methods are disclosed
as exemplary implementations for communication between FC switches.

I/We claim:
1. A method for establishing a connection between two Fibre Channel (FC)
switches (106), the method comprising:
receiving, by a relay system (102), an Exchange Link Parameters (ELP)
packet from a first Fibre Channel (FC) switch (106-1), wherein the first F5 C
switch (106-1) is connected to the relay system (102) through a first
Expansion Port (E_Port) (104-1) of the relay system (102);
determining the ELP packet to be indicative of a request to establish a
connection between the first FC switch (106-1) and a second FC switch (106-
10 3), wherein the second FC switch (106-3) is connected to the relay system
(102) through a second E_Port (104-4) of the relay system (102);
transmitting an updated ELP packet to the second FC switch (106-3)
through the second E_Port (104-4) for facilitating establishment of the
connection, wherein the updated ELP packet comprises at least one parameter
15 corresponding to the second E_Port (104-4);
receiving, from the second FC switch (106-3), a connection
establishment response message responsive to the transmitting the updated
ELP packet, wherein the connection establishment request indicates one of an
acceptance and rejection to establish the connection; and
20 transmitting an updated connection establishment message to the first FC
switch (106-1) through the first E_Port (104-1) for establishing the connection
between the first FC switch (106-1) and the second FC switch (106-3),
wherein the updated connection establishment message comprises at least one
parameter corresponding to the first E_Port (104-1).
25 2. The method as claimed in claim 1, wherein the method further comprises
replacing an initial value of the at least one parameter of the ELP packet with
a value corresponding to the second E_Port (104-4) for obtaining the updated
21
ELP packet, wherein the initial value of the at least one parameter of the ELP
packet corresponds to a port of the first FC switch (106-1).
3. The method as claimed in claim 1, wherein the method further comprises
replacing an initial value of the at least one parameter of the connection
establishment response message with a value corresponding to the first E_Por5 t
(104-1) for obtaining the updated connection establishment response message,
wherein the initial value of the at least one parameter of the connection
establishment response message corresponds to a port of the second FC
switch (106-3).
10 4. The method as claimed in claim 1, wherein the method further comprises:
receiving, from the second FC switch (106-3), an acknowledgement
message responsive to the transmitting the updated ELP packet, wherein the
acknowledge message indicates a successful reception of the updated ELP
packet; and
15 transmitting the acknowledgement message to the first FC switch (106-
1).
5. The method as claimed in claim 1, wherein the method further comprises:
receiving, from the first FC switch (106-1), another acknowledgement
message responsive to the connection establishment response message,
20 wherein the acknowledge message indicates a successful reception of the
updated connection establishment response message; and
transmitting the other acknowledgement message to the second FC
switch (106-3).
6. A relay system (102) comprising:
25 a processor; and
a packet update module coupled to the processor to,
22
receive an Exchange Link Parameters (ELP) packet from a first
Fibre Channel (FC) switch, wherein the first FC switch (106-1) is
connected to the relay system (102) through a first Expansion Port
(E_Port) of the relay system (102);
determine the ELP packet to be indicative of a request to establis5 h
a connection between the first FC switch (106-1) and a second FC switch
(106-3), wherein the second FC switch (106-3) is connected to the relay
system (102) through a second E_Port (104-4) of the relay system (102);
transmit an updated ELP packet to the second FC switch (106-3)
10 through the second E_Port (104-4) for facilitating establishment of the
connection, wherein the updated ELP packet comprises at least one
parameter corresponding to the second E_Port (104-4);
receiving, from the second FC switch (106-3), a connection
establishment response message responsive to the transmitting the
15 updated ELP packet, wherein the connection establishment request
indicates one of an acceptance and rejection to establish the connection;
and
transmit an updated connection establishment message to the first
FC switch (106-1) through the first E_Port (104-1) for establishing the
20 connection between the first FC switch (106-1) and the second FC switch
(106-3), wherein the updated connection establishment message
comprises at least one parameter corresponding to the first E_Port (104-
1).
7. The relay system (102) as claimed in claim 6, wherein the packet update
25 module further is to,
replace an initial value of the at least one parameter of the ELP packet
with a value corresponding to the second E_Port (104-4) for obtaining the
23
updated ELP packet, wherein the initial value of the at least one parameter of
the ELP packet corresponds to a port of the first FC switch (106-1); and
replace an initial value of the at least one parameter of the connection
establishment response message with a value corresponding to the first E_Port
(104-1) for obtaining the updated connection establishment response message5 ,
wherein the initial value of the at least one parameter of the connection
establishment response message corresponds to a port of the second FC
switch (106-3).
8. The relay system (102) as claimed in claim 6, wherein the packet update
10 module further is to,
receive an acknowledgement message responsive to the updated ELP
packet from the second FC switch (106-3), wherein the acknowledge message
indicates a successful reception of the updated ELP packet; and
transmit the acknowledgement message to the first FC switch (106-1).
15 9. The relay system (102) as claimed in claim 6, wherein the packet update
module further is to,
receive another acknowledgement message responsive to the connection
establishment response message from the first FC switch (106-1), wherein the
acknowledge message indicates a successful reception of the updated
20 connection establishment response message; and
transmit the other acknowledgement message to the second FC switch
(106-3).
10. The relay system (102) as claimed in claim 6, wherein the relay system (102)
comprises a plurality of E_Ports.
25 11. A non-transitory computer-readable medium having embodied thereon a
computer program for executing a method comprising:
24
receiving, by a relay system (102), an Exchange Link Parameters (ELP)
packet from a first Fibre Channel (FC) switch (106-1), wherein the first FC
switch (106-1) is connected to the relay system (102) through a first
Expansion Port (E_Port) of the relay system (102);
determining the ELP packet to be indicative of a request to establish 5 a
connection between the first FC switch (106-1) and a second FC switch (106-
3), wherein the second FC switch (106-3) is connected to the relay system
(102) through a second E_Port (104-4) of the relay system (102);
transmitting an updated ELP packet to the second FC switch (106-3)
10 through the second E_Port (104-4) for facilitating establishment of the
connection, wherein the updated ELP packet comprises at least one parameter
corresponding to the second E_Port (104-4);
receiving, from the second FC switch (106-3), a connection
establishment response message responsive to the transmitting the updated
15 ELP packet, wherein the connection establishment request indicates one of an
acceptance and rejection to establish the connection; and
transmitting an updated connection establishment message to the first FC
switch (106-1) through the first E_Port (104-1) for establishing the connection
between the first FC switch (106-1) and the second FC switch (106-3),
20 wherein the updated connection establishment message comprises at least one
parameter corresponding to the first E_Port (104-1).