Multicast Inter-AS VPN: Overcoming Option B Limitations with BGP Attribute

Overcoming Option B Limitations with BGP Attribute


In Multicast Inter-AS VPN context that are based in the first MVPN generation, which BGP attribute overcome the option B limitation due to a rewritten originator next-hop address in the network?



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A. B. C. D.



In a Multicast Inter-AS VPN context based on the first generation of Multicast VPN (M VPN) technology, there is a limitation known as "Option B" that arises when the originator next-hop address is rewritten in the network. This limitation refers to the fact that when a multicast packet traverses multiple autonomous systems (ASes), the intermediate ASes may not have visibility of the originator next-hop address, which can result in suboptimal multicast routing paths.

To overcome this limitation, BGP (Border Gateway Protocol) can be used to carry multicast traffic across AS boundaries. In this context, BGP carries multicast routing information and uses a set of BGP attributes to determine the best path for multicast traffic.

The BGP attribute that overcomes the Option B limitation is the "originator" attribute. The originator attribute is a non-transitive optional attribute that is used to indicate the router ID of the PIM (Protocol Independent Multicast) domain that originated a multicast route.

When a multicast route is propagated across AS boundaries, the originator attribute is added to the BGP update message. This allows intermediate ASes to determine the correct path for the multicast traffic, even if the originator next-hop address has been rewritten in the network.

Therefore, in a Multicast Inter-AS VPN context based on the first generation of M VPN technology, the correct answer to the question is C. originator.