Inter-fabric routing

• US 20060034302A1
• Filed: 05/26/2005
• Published: 02/16/2006
• Est. Priority Date: 07/19/2004
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Brocade Communications Systems, Inc. (Broadcom, Inc.)
• Inventors: Peterson, David
• Granted Patent: US 8,018,936 B2
• Time in Patent Office: Days
• US Class Current: 370/401
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/357 Fibre channel switches

Abstract

A method and apparatus is shown for communicating Fibre Channel frames between distinct fabrics. A proxy zone is established in each fabric with a physically present local device and a remote fabric device. A router creates a proxy device in each fabric for every device not physically connected to the fabric. The proxy devices appear to be directly attached to the router. The router handles all address translations between proxy and physical addresses. When multiple routers are encountered, the ingress router does all address translation. No routing or encapsulation headers are used except when routing between two routers. The source ID and the originator exchange identifier are stored at the egress router for all link requests that require special handling. When replies pass through that router, the destination ID and originator exchange identifier are compared with the stored information. On a match, the reply is specially handled.

Claims

1. A router for transmitting Fibre Channel frames between devices having world wide names and physical port addresses, the router comprising:

a) an ingress port that receives a first frame from a first fabric, the first frame having a source ID corresponding to the physical port address of a first device and a destination ID corresponding to a first proxy address for a first proxy device, the first physical port address of the first device and the first proxy address both being Fibre Channel addresses found on the first fabric;

b) an egress port that transmits the first frame to a second device on a second fabric, the second device having

i) a world wide name that is the same as the word wide name of the first proxy device, and

ii) a physical port address that is an address on the second fabric;

c) a fabric router logic component containing programming to

i) translate the destination ID of the first frame from the first proxy address to the physical port address of the second device, and

ii) translate the source ID of the first frame from the physical port address of the first device to a second proxy address, the second proxy address representing an address on the second fabric for a second proxy device, the second proxy device having a world wide name that is the same as the word wide name of the first device;

2. A system of Fibre Channel communication between devices having world wide names comprising

a) a first Fibre Channel fabric having

i) a first device with a first device physical address;

ii) a first proxy device with a first proxy device address;

b) a second Fibre Channel fabric having

i) a second device with a second device physical address, the second device having a world wide name that is the same as the word wide name of the first proxy device;

ii) a second proxy device with a second proxy device address, the second proxy device having a world wide name that is the same as the word wide name of the first device;

c) a Fibre Channel frame being sent from the first device to the second device, the frame have a destination ID and a source ID;

d) an ingress router physically connected to the first fabric, the ingress router having

i) a fabric router logic component containing programming to translate the destination ID of the Fibre Channel frame from the first proxy device address to the second device physical address and to translate the source ID of the Fibre Channel frame from the first device physical address to the second proxy device address,

ii) a first ingress port that receives the Fibre Channel frame from the first fabric, and

iii) a first egress port that transmits the Fibre Channel frame after the destination ID and source ID are translated by the fabric router logic;

e) an egress router physically connected to the second fabric, the egress router having

i) a second ingress port that communicates with the first egress port of the ingress router;

ii) a second egress port that transmits the Fibre Channel frame to the second fabric wherein the egress router does not translate the destination ID or the source ID of the Fibre Channel frame.

3. The system of claim 2, wherein the Fibre Channel frame is transmitted from the first egress port to the second ingress port without any additional header added to the Fibre Channel frame at the ingress router and without any header being removed at the egress router before the Fibre Channel frame is transmitted to the second fabric.

4. The system of claim 2, further comprising a wide area network connecting the first egress port of the ingress router to the second ingress port of the egress router.

5. The system of claim 4, wherein the wide area network has a protocol chosen from the group consisting of SONET and Gigabit Ethernet.

6. The system of claim 2, further comprising a third Fibre Channel fabric connecting the first egress port of the ingress router to the second ingress port of the egress router.

7. The system of claim 6, wherein the fabric router logic of the ingress port adds an inter-fabric routing header to the Fibre Channel frame before the frame is transmitted on the first egress port.

8. The system of claim 7, wherein the inter-fabric routing header comprises a hop count field and an expiration time field.

9. The system of claim 7, wherein the inter-fabric routing header comprises a source fabric identifier field that identifies the first fabric and a destination fabric identifier field that identifies the second fabric.

10. The system of claim 9, further comprising a device on the third Fibre Channel fabric that uses the destination fabric identifier field to route the Fibre Channel frame to the egress router.

11. The system of claim 7, wherein the fabric router logic of the ingress port adds an encapsulation header to the Fibre Channel frame after the inter-fabric routing header has been added to the Fibre Channel frame.

12. The system of claim 2, wherein the Fibre Channel frame is a link service frame containing a port address in a payload, and further wherein the fabric router logic identifies the frame as a link service frame needing special handling by examining a header on the frame.

13. The system of claim 12, wherein the examination of the frame for special handling includes examining a R_CTL value and a command field.

14. The system of claim 12, wherein the egress router contains an egress fabric router logic with programming to determine that the frame is a link service frame that needs special handling, and that stores the source identifier and an exchange identifier in local memory.

15. The system of claim 14, further comprising a link service reply frame being sent from the second device to the first device, and further wherein the egress fabric router logic identifies the link service reply frame by comparing a destination address and an exchange identifier found in the link service reply frame with the stored source identifier and exchange identifier found in the local memory.

16. The system of claim 15, wherein the link service reply frame contains a port identifier in a data payload that is translated by the egress fabric router after the link service reply frame is identified.

17. The system of claim 2, wherein the first device physical address in the first fabric exactly matches a conflicting device physical address in the second fabric.

18. A method for transmitting a Fibre Channel frame from a first device on a first fabric to a second device on a second fabric comprising:

a) at a first router,

i) receiving the frame from the first fabric;

ii) translating a destination address in the frame from a first fabric proxy address for the second device to a second fabric physical device address for the second device;

iii) translating a source address in the frame from a first fabric physical device address for the first device to a second fabric proxy address for the first device

b) next, transmitting the frame from the first router to a second router;

c) at the second router,

i) transmitting the frame to the second device across the second fabric.

19. The method of claim 18, wherein the steps at the first router further comprises identifying that the frame is a link service request requiring special handling and translating a port identifier in a payload of the frame.

20. The method of claim 19, wherein the steps at the second router further comprises identifying the frame as a link service request requiring special handling and storing the source address and an exchange identifier at the second router, and further comprising:

d) receiving a link service reply frame from the second device at the second router;

e) identifying the link service reply frame by comparing a reply destination address and a reply exchange identifier in the link service reply frame with the previously stored source address and exchange identifier from the link service request frame; and

e) translating a reply port identifier in a payload of the link service reply frame.