6PE – IPv6 over MPLS
6PE is a really cool feature which allows IPv6 islands to communicate with each other over an MPLS/IPv4 core network. IPv4 addresses space is fast running out so familiarising yourself with IPv6 is probably a good idea.
Consider the toplogy below.
Service providers can leverage their MPLS networks to deliver IPv6 solutions without having to rearchitect their networks. The PE devices are configured with IPv6 routing capability, however the P nodes have no IPv6 routing functionality enabled.
Data packets are encapsualted into MPLS frames on the ingress PE with two labels, the bottom of the stack label being the label assigned to the IPv6 prefix and the top label which is used to forward the packet has a label binding of the PE3s loopback 0 address.
From 6PE2 if we do a cef lookup for the IPv6 prefix connected to 6PE1 we see the following.
6PE2#sh ipv6 cef 2001:2::
2001:2::/64
nexthop 10.0.0.5 FastEthernet1/0 label 16 19
The bottom of stack label ie 19 is the ipv6 label and can be verified on 6PE2 as below.
6PE2#sh ip bgp ipv6 unicast labels
Network Next Hop In label/Out label
2001:2::/64 ::FFFF:1.1.1.1 nolabel/19
The top label ie 16 is generated from a recursive lookup which points to the remote 6PE device ie 6PE1s loopback address.
6PE2#sh ip cef 1.1.1.1
1.1.1.1/32
nexthop 10.0.0.5 FastEthernet1/0 label 16
6PE2#
the 6CEs can use an IPv6 IGP for 6PE-to-6CE connectivity or they can rely on static routing. In this case static routing has been configured as below.
ipv6 route ::/0 FastEthernet1/0 2001:2::2
Watch the video below or download it and watch it on your iPod or iPhone.
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I made a post with pictorial view http://www.mplsvpn.info/2010/03/ipv6-from-mpls.html