Patent ID: 7865615
Filing Date: 2011-01-04
Classification: H04L

Abstract:
1. A method for maintaining Interior Gateway Protocol (IGP) transparency of Virtual Private Network (VPN) routes when Border Gateway Protocol (BGP) is used as a Provider Edge Device (PE) to Customer Edge Device (CE) protocol, the method comprising: generating a BGP advertisement at a first CE to advertise one or more internal VPN routes from the first CE to a second CE, wherein the first and second CEs are in the same customer network, the BGP advertisement having one or more transitive attributes that carry IGP path attributes for the advertised routes; sending the BGP advertisement from the first CE to a first PE; propagating the BGP advertisement from the first PE among devices of a provider network while maintaining the transitive attributes that carry IGP path attributes, one of the devices being a second PE; sending the BGP advertisement from the second PE to a second CE, along with the transitive attributes that carry IGP path attributes; receiving, at the second CE the BGP advertisement of VPN routes of the same customer network via the second PE; and in response, converting the BGP advertisement and transitive attributes that carry IGP path attributes at the second CE into corresponding IGP advertisements of the one or more internal VPN routes, wherein the method further comprises increasing an administrative distance of a BGP instance on the first CE within the BGP advertisement to persuade the second CE to select routes internal to the customer network rather than received routes from the BGP advertisement of the customer network.