SEGMENT ROUTING EXTENSION HEADERS

• US 20150256456A1
• Filed: 03/14/2014
• Published: 09/10/2015
• Est. Priority Date: 03/06/2014
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Previdi, Stefano B., Filsfils, Clarence
• Granted Patent: US 9,762,488 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 45/308 Route determination based on user's profile, e.g. premium users
• CPC Class Codes: H04L 45/745 Address table lookup; Address filtering
• CPC Class Codes: H04L 69/166 IP fragmentation; TCP segmentation
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers

Abstract

A system and method are disclosed for using segment routing (SR) in native IP networks. The method involves receiving a packet. The packet is an IP packet and includes an IP header. The method also involves updating the packet. Updating the packet involves writing information, including a segment routing segment identifier, to the destination address of the packet.

Claims

1. A method comprising:

receiving a packet, wherein

the packet comprises an internet protocol (IP) header; and

updating the packet, wherein

the updating comprises writing information to a destination address of the IP header, and

the information comprises a segment identifier (SID).

2. The method of claim 1, further comprising:

writing a first segment routing (SR) extension header to the packet.

3. The method of claim 2, wherein

the first SR extension header comprises a segment list and a policy list.

4. The method of claim 2, further comprising:

writing a second SR extension header to the packet.

5. The method of claim 4, further comprising:

updating the first SR extension header, wherein

the updating the first SR extension header comprises calculating an offset; and

updating the second extension header, wherein

the updating the second SR extension header comprises pushing a segment list element onto a segment list included in the second extension header.

6. The method of claim 3, further comprising:

calculating a length of a segment list element of the segment list.

7. The method of claim 1, further comprising:

detecting whether the packet comprises a segment routing protocol identifier (SRPID).

8. The method of claim 4, further comprising:

determining whether the packet has traversed a path specified by the first SR extension header,

wherein

the determining is based on the second SR extension header.

9. The method of claim 3, further comprising:

writing an IP destination address into a final segment list element of the segment list.

10. A system comprising:

a first node configured to

receive a packet, wherein

the packet comprises an internet protocol (IP) header; and

update the packet, wherein

updating the packet comprises writing information to a destination address of the IP header, and

the information comprises a segment identifier (SID).

11. The system of claim 10, wherein the first node is further configured to:

write a first segment routing (SR) extension header to the packet, wherein

the first SR extension header comprises a segment list and a policy list.

12. The system of claim 11, wherein the first node is further configured to:

write a second SR extension header to the packet.

13. The system of claim 12, wherein the first node is further configured to:

update the first SR extension header, wherein

updating the first SR extension header comprises calculating an offset; and

update the second extension header, wherein

updating the second SR extension header comprises pushing a segment list element onto a segment list included in the second extension header.

14. The system of claim 11, wherein the first node is further configured to:

calculate a length of a segment list element of the segment list.

15. The system of claim 12, wherein the first node is further configured to:

determine, based on the second SR extension header whether the packet has traversed a path specified by the first SR extension header.

16. A non-transitory computer readable medium comprising executable instructions, wherein a method is implemented in response to executing the instructions, the method comprising:

receiving a packet, wherein

the packet comprises an internet protocol (IP) header; and

updating the packet, wherein

the updating comprises writing information to a destination address of the IP header, and

the information comprises a segment identifier (SID).

17. The non-transitory computer readable medium of claim 16 wherein the method further comprises:

writing a first segment routing (SR) extension header to the packet, wherein

the first SR extension header comprises a segment list and a policy list; and

writing a second SR extension header to the packet.

18. The non-transitory computer readable medium of claim 17 wherein the method further comprises:

updating the first SR extension header, wherein

the updating the first SR extension header comprises calculating an offset; and

updating the second extension header, wherein

the updating the second SR extension header comprises pushing a segment list element onto a segment list included in the second extension header.

19. The non-transitory computer readable medium of claim 17 wherein the method further comprises:

calculating a length of a segment list element of the segment list.

20. The non-transitory computer readable medium of claim 17 wherein the method further comprises:

determining, based on the second SR extension header whether the packet has traversed a path specified by the first SR extension header.