# US 2013/0155845 A1 · Method for providing border gateway protocol fast convergence on autonomous system border routers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0155845 A1 - Document ID: US20130155845A1 - Status: Published application - Kind: A1 - Application number: 13/329,113 - Filed: 2011-12-16 - Published: 2013-06-20 - Earliest claimed: 2011-12-16 - Assignees: Cisco Technology, Inc. - Inventors: Keyur Patel; Robert Raszuk - Web page: https://patentgrep.com/patent/US20130155845A1 ## CPC - H04L 45/04: {Interdomain routing, e.g. hierarchical routing} - H04L 45/22: {Alternate routing} - H04L 45/28: using route fault recovery - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Techniques are disclosed for providing fast convergence on Autonomous System Border Routers (ASBRs). In an embodiment, an ASBR receives first Virtual Private Network (VPN) route information including a first route target, a first route distinguisher, and a first network prefix and second VPN route information including a second route target, a second route distinguisher and a second network prefix. The second route distinguisher received by the ASBR is different than the first route distinguisher. The ASBR compares the first route target to the second route target and the first network prefix with the second network prefix. In response to determining that the first route target matches the second route target and the first network prefix matches the second network prefix, the ASBR associates, in a routing table, a first path based on the first VPN route information with a second path based on the second VPN route information. ## Claims ### Claim 1 A method comprising: receiving at an Autonomous System Border Router (ASBR) first Virtual Private Network (VPN) route information including a first route target, a first route distinguisher, and a first network prefix; receiving at the ASBR, second VPN route information including a second route target, a second route distinguisher, and a second network prefix, wherein the second route distinguisher is different than the first route distinguisher; using the ASBR, comparing the first route target to the second route target and the first network prefix to the second network prefix; and in response to determining that the first route target matches the second route target and the first network prefix matches the second network prefix, associating in a routing table of the ASBR a first path based on the first VPN route information with a second path based on the second VPN route information. ### Claim 2 (depends on 1) The method of claim 1, wherein associating comprises computing a primary path and a backup path to a VPN site; wherein the primary path traverses a first provider edge (PE) router associated with the first VPN route information; wherein the backup path traverses a second provider edge (PE) router associated with the second VPN route information; installing the primary path and the backup path in the routing table of the ASBR. ### Claim 3 (depends on 2) The method of claim 2, further comprising: receiving a first network packet at the ASBR; wherein the VPN site is a destination associated with the first network packet; in response to receiving the first network packet, forwarding the first network packet along the primary path; receiving a second network packet at the ASBR; wherein the VPN site is a destination associated with the second network packet; detecting a failure along the primary path; in response to detecting the failure along the first path, forwarding the second packet along the backup path. ### Claim 4 (depends on 1) The method of claim 1, wherein the ASBR stores mapping data that maps route targets to site identifiers and wherein comparing comprises: searching the mapping data using the first route target to find a site identifier associated with the first route target: searching the mapping data using the second route target to find a site identifier associated with the second route target; determining whether the site identifier associated with the first route target and the site identifier associated with the second route target are the same. ### Claim 5 (depends on 1) The method of claim 1, further comprising: in response to determining that the first route target does not match the second route target or the first network prefix does not match the second network prefix, determining that the first path and the second path are not associated as a primary path and a backup path. ### Claim 6 (depends on 1) The method of claim 1, wherein the routing table is at least one of a Routing Information Base (RIB) or a Forwarding Information Base (FIB). ### Claim 7 (depends on 1) The method of claim 1, wherein the ASBR stores a list of disqualified route targets, the method further comprising: comparing the first route target and the second route target to the list of disqualified route targets; in response to determining that the first route target or the second route target is included on the list of disqualified route targets, determining that the first path and the second path are not associated as a primary path and a backup path. ### Claim 8 One or more non-transitory computer-readable storage media comprising one or more sequences of instructions which when executed cause one or more processors to perform: receiving at an Autonomous System Border Router (ASBR) first Virtual Private Network (VPN) route information including a first route target, a first route distinguisher, and a first network prefix; receiving at the ASBR, second VPN route information including a second route target, a second route distinguisher, and a second network prefix, wherein the second route distinguisher is different than the first route distinguisher; using the ASBR, comparing the first route target to the second route target and the first network prefix to the second network prefix; in response to determining that the first route target matches the second route target and the first network prefix matches the second network prefix, associating in a routing table of the ASBR a first path based on the first VPN route information with a second path based on the second VPN route information. ### Claim 9 (depends on 8) The one or more non-transitory computer-readable storage media of claim 8, wherein instructions for associating comprise instructions for: computing a primary path and a backup path to a VPN site; wherein the primary path traverses a first provider edge (PE) router associated with the first VPN route information; wherein the backup path traverses a second provider edge (PE) router associated with the second VPN route information; installing the primary path and the backup path in the routing table of the ASBR. ### Claim 10 (depends on 9) The one or more non-transitory computer-readable storage media of claim 9, wherein the instructions, when executed, further cause: receiving a first network packet at the ASBR; wherein the VPN site is a destination associated with the first network packet; in response to receiving the first network packet, forwarding the first network packet along the primary path; receiving a second network packet at the ASBR; wherein the VPN site is a destination associated with the second network packet; detecting a failure along the primary path; in response to detecting the failure along the first path, forwarding the second packet along the backup path. ### Claim 11 (depends on 8) The one or more non-transitory computer-readable storage media of claim 8, wherein the ASBR stores mapping data that maps route targets to site identifiers and wherein instructions for comparing comprise instructions for: searching the mapping data using the first route target to find a site identifier associated with the first route target: searching the mapping data using the second route target to find a site identifier associated with the second route target; determining whether the site identifier associated with the first route target and the site identifier associated with the second route target are the same. ### Claim 12 (depends on 8) The one or more non-transitory computer-readable storage media of claim 8, wherein the instructions, when executed, further cause: in response to determining that the first route target does not match the second route target or the first network prefix does not match the second network prefix, determining that the first path and the second path are not associated as a primary path and a backup path. ### Claim 13 (depends on 8) The one or more non-transitory computer-readable storage media of claim 8, wherein the routing table is at least one of a Routing Information Base (RIB) or a Forwarding Information Base (FIB). ### Claim 14 (depends on 8) The one or more non-transitory computer-readable storage media of claim 8, wherein the ASBR stores a list of disqualified route targets, wherein the instructions, when executed, further cause comparing the first route target and the second route target to the list of disqualified route targets; in response to determining that the first route target or the second route target is included on the list of disqualified route targets, determining that the first path and the second path are not associated as a primary path and a backup path. ### Claim 15 An apparatus comprising: one or more digital electronic central processing units (CPUs); a communications interface coupled to the one or more CPUs and configured to: connect a first autonomous system to a second autonomous system; receive first Virtual Private Network (VPN) route information including a first route target, a first route distinguisher, and a first network prefix; receive second VPN route information including a second route target, a second route distinguisher, and a second network prefix, wherein the second route distinguisher is different than the first route distinguisher; electronic digital memory coupled to the one or more CPUs and comprising a routing table configured to store routing information identifying paths within the first autonomous system; logic coupled to the one or more CPUs and configured to: compare the first route target to the second route target and the first network prefix to the second network prefix; in response to determining that the first route target matches the second route target and the first network prefix matches the second network prefix, associate in the routing table a first path based on the first VPN route information with a second path based on the second VPN route information. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the logic for associating comprises logic for: computing a primary path and a backup path to a VPN site; wherein the primary path traverses a first provider edge (PE) router associated with the first VPN route information; wherein the backup path traverses a second provider edge (PE) router associated with the second VPN route information; installing the primary path and the backup path in the routing table. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the logic is further configured to: detect a failure along the primary path and wherein the communications interface is further configured to: receive a first network packet; wherein the VPN site is a destination associated with the first network packet; in response to receiving the first network packet, forward the first network packet along the primary path; receive a second network packet; wherein the VPN site is a destination associated with the second network packet; in response to the detected failure along the first path, forward the second packet along the backup path. ### Claim 18 (depends on 15) The apparatus of claim 15, further comprising mapping data that maps route targets to site identifiers and wherein logic for comparing comprise logic for: searching the mapping data using the first route target to find a site identifier associated with the first route target: searching the mapping data using the second route target to find a site identifier associated with the second route target; determining whether the site identifier associated with the first route target and the site identifier associated with the second route target are the same. ### Claim 19 (depends on 15) The apparatus of claim 15, wherein logic is further configured to: in response to determining that the first route target does not match the second route target or the first network prefix does not match the second network prefix, determine that the first path and the second path are not associated as a primary path and a backup path. ### Claim 20 (depends on 15) The apparatus of claim 15, wherein the routing table is at least one of a Routing Information Base (RIB) or a Forwarding Information Base (FIB).