Path selection using local preference in IPv6 is administered the same as with IPv4. Consider the following example:

The following is an example of an application of an IPv6 prefix-list: The prefix-list filters outbound and inbound routing updates to/from the ISP, respectively, to ensure that only large prefixes of the IPv6 global addressing space are allowed.

(See 12.28 - the process is exactly the same as for IPv4) As with IPv4, the filtering mechanisms applied to neighbor statements in the IPv6 address-family configuration are applied per-neighbor, and observe a particular order: For incoming routes: Route-map inFilter-list inPrefix-list in For outgoing routes: Prefix-list outFilter-list outRoute-map out

Here are the pros and cons of single BGP transport (one transport using IPv4 for both IPv4 and IPv6 routing information) versus dual transport (IPv4 and IPv6 routing information have individual neighbors of the same protocol). With a single IPv4 TCP session: Reduction in the number of neighbors reduces complexity and makes troubleshooting easierTo properly … Continue reading 13.6 Comparing Single and Dual BGP Transport →

MP-BGP does not have a requirement to use IPv4 for transport when exchanging IPv6 routing information. IPv6 can be used for transport, too. Observe the following configuration: Consider the previous example, where an IPv4 session was used to exchange both IPv4 and IPv6 routing information. The difference here may be that we create two separate … Continue reading 13.4 Exchanging IPv6 Routes Over an IPv6 Session →

Again, with MP-BGP, the transport is independent of the NLRI, or payload, of the BGP peering session. So in the following example, you have two routers with an existing IPv4 peering session transporting both IPv4 and IPv6 advertisements. Note the activation of the IPv4 neighbor within the IPv6 address-family configuration. An IPv6 neighbor must be … Continue reading 13.3 Exchanging IPv6 Routes over an IPv4 Session →

Multiprotocol BGP enables the use of other protocols besides IPv4. It includes IPv6, as well as extensions thereof, including the following: NLRI (network-layer reachability information) in IPv6 formatNext-hop attribute in IPv6 format Note the caveat that the next-hop must be of the same address type/family as the NLRI exchanged, for instance, an IPv6 route cannot … Continue reading 13.2 MP-BGP Support for IPv6 →