Patent ID: 7986695

Claim:
A method comprising: receiving a plurality of routing protocol advertisements with a first network device from a plurality of other network devices within an existing virtual private network (VPN) to which the first network device belongs, wherein the advertisements include site-IDs currently used by the plurality of other network devices for identifying customer sites that are already configured on the plurality of other network devices for the VPN; configuring a new customer site of the VPN on the first network device; automatically selecting, from a set of unused site-IDs, a unique site-ID for the new customer site of the VPN based on the site-IDs included within the received advertisements; transmitting a claim advertisement for the selected site-ID with the first network device to the plurality of other network devices within the VPN; and determining, with the first network device, that a collision of site identifiers has occurred and that the site-ID selected for the new customer site conflicts with a site identifier currently used by one of the other routers for a different customer site of the VPN when the first network device receives a routing protocol advertisement from one of the plurality of other network devices that includes the selected site identifier during a predetermined period of time after transmitting the claim advertisement; upon determining that a collision has occurred, perform collision resolution by: comparing values of configuration flags included in the claim advertisement from the first network device and the one of the received advertisements from one of the plurality of other network devices within the VPN; resolving the collision in favor of the network device with the advertisement that includes the configuration flag indicating a manually configured site-ID when the configuration flags do not have the same value; comparing types of label blocks included in the claim advertisement and the one of the received advertisements when the configuration flags have the same value; resolving the collision in favor of the network device with the advertisement that includes the type of label block indicating a real advertisement with a non-zero label block size when the types of label blocks are not the same; comparing local preference values included in the claim advertisement and the one of the received advertisements when the types of label blocks are the same; resolving the collision in favor of the network device with the advertisement that includes a higher local preference value when the local preference values are not the same; comparing next-hop values included in the claim advertisement and the one of the received advertisements when the local preference values are the same; and resolving the collision in favor of the network device with the advertisement that includes a lower next-hop value.