Patent ID: 8228786

Claim:
A method for dynamically discovering shared risk node group (SRNG) membersips of a plurality of interconnected edge devices in a first routing domain, at least some of the plurality of interconnected edge devices being attached to peer devices located in a second routing domain, the method comprising: determining, at a first edge device of the plurality of interconnected edge devices in the first routing domain, a first set of identities of each peer device in the second routing domain attached to the first edge device in the first routing domain; receiving, in one or more advertisements from a second edge device of the plurality of interconnected edge devices in the first routing domain, at the first edge device, a second set of identities of each peer device in the second routing domain attached to the second edge device; storing the first set of identities and the second set of identities in a table that includes a plurality of entries, wherein each entry of the plurality of entries associates an address prefixes reachable in the second routing domain, with an identity of a peer device in the second routing domain which advertised the address prefix and with one or more attached edge devices of the plurality of interconnected edge devices in the first routing domain that represent a next-hop for the address prefix; determining a set of entries from the plurality of entries stored in the table by identifying entries with a same address prefix; determining a subset of entries from the set of entries by identifying entries of the set of entries with a same identity of a peer device in the second routing domain; identifying different edge devices of the plurality of interconnected edge devices in the first routing domain that are associated with each entry of the subset of entries as members of a SRNG, wherein the SRNG indicates that each edge device of the different edge devices would be impacted by a single failure; and using an edge device's membership in the SRNG in an application.