| 摘要 |
A virtual private network (VPN) is formed with a pair of autonomous systems (ASes) connected by each having at least two autonomous system border routers (ASBRs) connected to the corresponding ASBRs at the other AS, referred to as an Option B VPN-IPv4 network. Route reflectors (RRs) only reflect the best Border Gateway Protocol (BGP) paths, providing no backup BGP paths for fast convergence. Advantageously, an automatic route distinguisher (RD) rewrite component at the ASBRs creates unique prefixes and advertises the original RD as transitive attribute in an update message to external AS peers. Each RD gets mapped to another unique prefix at the ASBR and also that two ASBRs will create different unique prefixes. Thus, the route reflector sees different prefixes and reflects all of them. The ingress provider edge (PE) router can import the prefixes and correctly obtain the alternate paths for fast convergence.
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