Using border gateway protocol to expose maximum segment identifier depth to an external application

Patent metadata

Field	Value
Publication number	US-10673753-B2
Application number	US-201815947737-A
Country	US
Kind code	B2
Filing date	Apr 6, 2018
Priority date	Jul 2, 2015
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

A method implemented by a network device acting as a border gateway protocol (BGP) speaker, of exposing a maximum segment identifier depth (MSD) value of the network device is described. The method comprises encoding the MSD value into a BGP Link State (BGP-LS) extension message. The BGP-LS extension message includes a type, a length and a MSD value. The type indicates the type of the MSD value, the length indicates the length of the MSD value and the MSD value indicates a lowest MSD value supported by the network device for enabling segment routing. The method continues with transmitting the BGP-LS extension message including the type, the length, and the MSD value to a network controller, where the network controller is to use the MSD value to compute a segment routing path including the network device.

First claim

What is claimed is:

1. A method implemented by a network node, of signaling a maximum segment identifier depth (MSD) of the network node to a centralized controller, the method comprising:
encoding the MSD into an attribute Type Length Value (TLV) including a type, a length and a value, wherein the type indicates the type of the MSD, the length indicates the length of the MSD and the value is a number that is a maximum number of segment routing (SR) labels that the network node is capable of imposing, wherein an SR label is used for steering a packet through an SR network, wherein the type of the attribute TLV indicates that the MSD is a link MSD and the value of the attribute TLV is a lowest MSD supported by a link of the network node; and
transmitting the attribute TLV to the centralized controller, wherein the centralized controller is to use the attribute TLV to compute an SR tunnel and the label stack depth of the SR tunnel does not exceed the MSD supported by the network node.

2. The method of claim 1 , wherein the network node is an ingress node of the SR tunnel.

3. The method of claim 1 , wherein the attribute TLV is a border gateway protocol Link State (BGP-LS) extension message.

4. The method of claim 1 , wherein the network node does not support Path Computation Element Communication Protocol (PCEP).

5. The method of claim 1 , wherein the network node does not participate in Interior Gateway Protocol(s) (IGP).

6. A network node for signaling a maximum segment identifier depth (MSD) of the network node to a centralized controller, comprising:
a processor and a memory, said memory containing instructions executable by the processor to cause the network node to:
encode the MSD into an attribute Type Length Value (TLV) including a type, a length and a value, wherein the type indicates the type of the MSD, the length indicates the length of the MSD and the value is a number that is a maximum number of segment routing (SR) labels that the network node is capable of imposing, wherein an SR label is used for steering a packet through an SR network, wherein the type of the attribute TLV indicates that the MSD is a link MSD and the value of the attribute TLV is a lowest MSD supported by a link of the network node; and
transmit the attribute TLV to the centralized controller, wherein the centralized controller is to use the attribute TLV to compute an SR tunnel and the label stack depth of the SR tunnel does not exceed the MSD supported by the network node.

7. The network node of claim 6 , wherein the network node is an ingress node of the SR tunnel.

8. The network node of claim 6 , wherein the attribute TLV is a border gateway protocol Link State (BGP-LS) extension message.

9. The network node of claim 6 , wherein the network node does not support Path Computation Element Communication Protocol (PCEP).

10. The network node of claim 6 , wherein the network node does not participate in Interior Gateway Protocol(s) (IGP).

11. A non-transitory machine-readable storage medium that provides instructions that, if executed by a processor of a network node, will cause said processor to perform operations comprising:
encoding a maximum segment identifier depth (MSD) of the network node into an attribute Type Length Value (TLV) including a type, a length and a value, wherein the type indicates the type of the MSD, the length indicates the length of the MSD and the value is a number that is a maximum number of segment routing (SR) labels that the network node is capable of imposing, wherein an SR label is used for steering a packet through an SR network, wherein the type of the attribute TLV indicates that the MSD is a link MSD and the value of the attribute TLV is a lowest MSD supported by a link of the network node; and
transmitting the attribute TLV to a centralized controller, wherein the centralized controller is to use the attribute TLV to compute an SR tunnel and the label stack depth of the SR tunnel does not exceed the MSD supported by the network node.

12. The non-transitory machine-readable storage medium of claim 11 , wherein the network node is an ingress node of the SR tunnel.

13. The non-transitory machine-readable storage medium of claim 11 , wherein the attribute TLV is a border gateway protocol Link State (BGP-LS) extension message.

14. The non-transitory machine-readable storage medium of claim 11 , wherein the network node does not support Path Computation Element Communication Protocol (PCEP).

15. The non-transitory machine-readable storage medium of claim 11 , wherein the network node does not participate in Interior Gateway Protocol(s) (IGP).

16. A method in a network controller, the method comprising:
receiving from a network node an attribute Type Length Value (TLV) including a type, a length and a value;
decoding the attribute TLV, to extract a maximum segment identifier depth (MSD) of the network node, wherein the type of the attribute TLV indicates the type of the MSD, the length of the attribute TLV indicates the length of the MSD and the value of the attribute TLV is a number that is a maximum number of segment routing (SR) labels that the network node is capable of imposing, wherein an SR label is used for steering a packet through an SR network, and wherein the type of the attribute TLV indicates that the MSD is a link MSD and the value of the attribute TLV is a lowest MSD supported by a link of the network node; and
computing, using the MSD, an SR tunnel including the network node, wherein the SR tunnel has a label stack depth that is lower than or equal to the MSD of the network node.

17. The method of claim 16 , wherein the network node is an ingress node of the SR tunnel.

18. The method of claim 16 , wherein the attribute TLV is a border gateway protocol Link State (BGP-LS) extension message.

19. The method of claim 16 , wherein the network node does not support Path Computation Element Communication Protocol (PCEP).

20. The method of claim 16 , wherein the network node does not participate in Interior Gateway Protocol(s) (IGP).

21. A centralized controller comprising:
a processor and a memory, said memory containing instructions executable by the processor to cause the centralized controller to:
receive from a network node an attribute Type Length Value (TLV) including a type, a length and a value; and
decode the attribute TLV, to extract a maximum segment identifier depth (MSD) of the network node, wherein the type of the attribute TLV indicates the type of the MSD, the length of the attribute TLV indicates the length of the MSD and the value of the attribute TLV is a number that is a maximum number of segment routing (SR) labels that the network node is capable of imposing, wherein an SR label is used for steering a packet through an SR network, and wherein the type of the attribute TLV indicates that the MSD is a link MSD and the value of the attribute TLV is a lowest MSD supported by a link of the network node; and
compute, using the MSD, an SR tunnel including the network node, wherein the SR tunnel has a label stack depth that is lower than or equal to the MSD of the network node.

22. The centralized controller of claim 21 , wherein the network node is an ingress node of the SR tunnel.

23. The centralized controller of claim 21 , wherein the attribute TLV is a border gateway protocol Link State (BGP-LS) extension message.

24. The centralized controller of claim 21 , wherein the network node does not

Assignees

• Ericsson Telefon Ab L M

Inventors

• Tantsura Evgeny
• Mirsky Gregory

Classifications

• H04L45/02

  Topology update or discovery · CPC title

• H04L45/72 Primary

  Routing based on the source address · CPC title

• H04L45/507

  Label distribution · CPC title