Resource reservation protocol (RSVP) U-turn detour label switched path (LSP)
AssigneeJuniper Networks, Inc.
InventorsBalaji Rajagopalan, Chandrasekar Ramachandran, Vali Mohammed Sunesara
Life of this patent
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Abstract
U-Turn detour paths, though the head-end router of a primary label switched path (LSP), are configured and used to enable fast failover to a secondary LSP, while avoiding reserving bandwidth (e.g., on links unused by primary and secondary paths) unnecessarily.
Claims20
A computer-implemented method for use by a head-end router, the computer-implemented method being associated with establishing detours in a primary path of an RSVP tunnel from the head-end router to an egress router, the primary path to include at least one transit router between the head-end router and the egress router, the computer-implemented method comprising:
- a) configuring the primary path to use detour local protection;
- b) generating, by the head-end router, a message including (1) first data indicating whether or not a “U-Turn” label switched path (LSP) is available in the head-end router, and (2) second data indicating that the head-end router would like each of the at least one transit router in the primary path to perform a U-Turn when computing a detour LSP such that the detour LSP may only include routers on the primary path between the transit router and the head-end router and may only include links on the primary path between the transit router and the head-end router that already have bandwidth reserved for the primary path;
- and
- c) transmitting the message for receipt by each of the at least one transit router in the primary path.
A computer-implemented method for use by a transit router, the computer-implemented method being associated with establishing detours in a primary path, to include the transit router, in an RSVP tunnel from a head-end router to an egress router, the computer-implemented method comprising:
- a) receiving, by the transit router, a message including (1) first data indicating that a “U-Turn” label switched path (LSP) is available in the head-end router, and (2) second data indicating that the head-end router would like the transit router in the primary path to perform a U-Turn when computing a detour LSP such that the detour LSP may only include routers on the primary path between the transit router and the head-end router and may only include links on the primary path between the transit router and the head-end router that already have bandwidth reserved for the primary path;
- b) responsive to receiving the message, computing, by the transit router, a U-Turn detour LSP
- 1) using a reverse path of the primary path, from the transit router to the head-end router, and
- 2) leaving a last hop of the U-turn detour LSP “loose” so that the head-end router can merge it with a secondary path in the RSVP tunnel.
A system comprising:
- a) a head-end router with (1) a primary path of an RSVP tunnel to an egress router, and (2) a secondary path of the RSVP tunnel to the egress router, wherein the secondary path is disjoint from the primary path;
- and
- b) at least one transit router on the primary path between the head-end router and the egress router,
- wherein one of the at least one transit router on the primary path is configured such that, responsive to determining that a next link or a next node on the primary path is unavailable for forwarding, the one of the at least one transit router performs a U-Turn detour of any packets received on the primary path so that the packets are sent back to the head-end router without using nodes or links not on the primary path whereby the links on the primary path already have bandwidth reserved for the primary path.
Dependencies are inferred from the claim text.