Scalable edge node protection using segment routing

Patent metadata

Field	Value
Publication number	US-9525619-B2
Application number	US-201314078219-A
Country	US
Kind code	B2
Filing date	Nov 12, 2013
Priority date	Oct 17, 2013
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

In one embodiment, a method comprises generating, by a first provider edge router associated with a first segment identifier, a primary label for reaching a destination, and repair information for reaching the destination if a second provider edge router is unavailable to reach the destination; allocating, by the first provider edge router, a first protected next-hop address associated with the first segment identifier for protected reachability to at least the destination; and sending via a core network, by the first provider edge router, an advertisement specifying the label and the repair information, enabling an ingress provider edge router to insert, into a data packet destined for the destination, the labels from the first provider edge router and the second provider edge router based on the repair information, for fast rerouting to the destination via one of the first or second provider edge router if the other is unavailable.

First claim

What is claimed is:

1. A method comprising:
generating, by a first provider edge router associated with a first segment identifier and positioned at a first edge of a core network, a primary multiprotocol label switching (MPLS) label for reaching a destination outside the core network, and repair information for reaching the destination if a second provider edge router positioned at a second edge of the core network is unavailable to reach the destination outside the core network;
allocating, by the first provider edge router, a first protected next-hop address associated with the first segment identifier for protected reachability to at least the destination, and advertising in the core network that the first protected next-hop address is reachable via the first segment identifier; and
sending via the core network, by the first provider edge router, an advertisement specifying the primary MPLS label and the repair information, enabling an ingress provider edge router positioned at a third edge of the core network to insert, into a data packet destined for the destination, one of the primary MPLS label from the first provider edge router and the corresponding repair information from the second provider edge router, or the corresponding primary MPLS label from the second provider edge router and the repair information from the first provider edge router, for MPLS-based multi-hop segment routing of the data packet and fast rerouting of the data packet to the destination via one of the first or second provider edge router if the other is unavailable.

2. The method of claim 1 , further comprising outputting a second advertisement enabling a BGP-free core network router in the core network to route the data packet to one of the first or second provider edge routers based on semantics specified in the second advertisement.

3. The method of claim 2 , wherein:
the primary MPLS label generated by the first provider edge router is for reaching a corresponding virtual private network (VPN) address prefix at the destination;
the core network router is a penultimate hop router for the first provider edge router;
the semantics cause the core network router to expose, in the data packet, the primary MPLS label if the first provider edge router is available;
the semantics further causing the core network router to expose, in the data packet, a label specifying a second segment identifier associated with the second provider edge router if the first provider edge router is unavailable.

4. The method of claim 3 , wherein the semantics further cause the core network router to expose the primary MPLS label if the first provider edge is available based on:
popping a label specifying the first segment identifier and used for the multi-hop segment routing of the data packet from the ingress provider edge router to the core network router via the core network;
popping a label specifying the second segment identifier underlying the label specifying the first segment identifier; and
popping the repair information, implemented as an MPLS repair label, underlying the label specifying the second identifier and overlying the primary MPLS label.

5. The method of claim 2 , wherein the second advertisement is flooded in the core network, the second advertisement specifying the first protected next-hop address, the first segment identifier, and the semantics as an extended service option of a link state data packet, the second advertisement enabling any router device to associate the first protected next-hop address with the first segment identifier.

6. The method of claim 1 , further comprising:
the first provider edge router receiving a data packet generated by the ingress provider edge router;
in response to the first provider edge router detecting the primary MPLS label of the first provider edge router as a top label of the data packet, the first provider edge router popping the top label and forwarding the data packet to the destination;
in response to the first provider edge router detecting the repair information from the first provider edge router as the top label, popping the top label and the primary MPLS label of the second provider edge router, underlying the top label, from the data packet and forwarding the data packet to the destination.

7. The method of claim 1 , wherein the repair information enables the ingress provider edge router to insert repair metadata identifying the one provider edge router if the other provider edge router is unavailable, the repair metadata identifying one of an Internet Protocol (IP) address or the first segment identifier for reaching the one provider edge router, and an MPLS repair label used by the one provider edge router for reaching the destination.

8. A method comprising:
receiving, by an ingress provider edge router positioned at a first edge of a core network, a first advertisement via the core network from a first provider edge router associated with a first segment identifier and positioned at a second edge of the core network, the first advertisement specifying a primary multiprotocol label switching (MPLS) label assigned by the first provider edge router and a first protected next hop address for reaching a destination outside the core network via the first provider edge router, and first repair information associated with reaching the destination;
receiving by the ingress provider edge router, via the core network, a second advertisement from a second provider edge router associated with a second segment identifier and positioned at a third edge of the core network, the second advertisement specifying a corresponding primary MPLS label assigned by the second provider edge router and a second protected next hop address for reaching the destination outside the core network via the second provider edge router, and second repair information associated with reaching the destination; and
selecting, by the ingress provider edge router, one of the first or second provider edge routers as a primary router for reaching the destination, and selecting the other of the first or second provider edge routers as a backup router for reaching the destination; and
inserting, into a data packet destined for the destination, the corresponding primary MPLS label of the primary router and the corresponding segment identifier, and the corresponding repair information of the backup router and the corresponding segment identifier, for MPLS-based multi-hop segment routing of the data packet that enables a core router in the core network to fast reroute the data packet from the primary router to the backup router if the primary router is unavailable.

9. The method of claim 8 , wherein:
the primary MPLS label assigned by the first provider edge router is a virtual private network (VPN) label for reaching a corresponding address prefix at the destination via the first provider edge router;
the first repair information includes a backup MPLS label for reaching the corresponding address prefix associated with the VPN label if the primary router is not available;
the label assigned by the second provider edge router is a corresponding primary MPLS label for reaching the corresponding address prefix at the destination via the second provider edge router;
the second repair information specifies that fast reroute to the destination is supported via the second protected next hop address of the second provider edge router if the primary router is not available.

10. The method of claim 9 , wherein the inserting includes:
inserting the VPN label overlying a destination address for the destination and payload for the data packet;
inserting the backup label overlying the VPN label;
inserting the second segment iden

Assignees

• Cisco Tech Inc

Inventors

• Filsfils Clarence
• Kumar Nagendra
• Bashandy Ahmed R
• Previdi Stefano Benedetto
• Francois Pierre Jean Rene
• Pignataro Carlos M

Classifications

• H04L45/22 Primary

  Alternate routing · CPC title

• H04L45/34

  Source routing · CPC title

• H04L45/02

  Topology update or discovery · CPC title

• H04L45/50

  using label swapping, e.g. multi-protocol label switch [MPLS] · CPC title

• H04L45/28

  using route fault recovery · CPC title