Configuring IP Router Parameters
42 Router Configuration Guide
IPv6 Provider Edge Router over MPLS (6PE)
6PE allows IPv6 domains to communicate with each other over an IPv4 MPLS core network.
This architecture requires no backbone infrastructure upgrades and no re-configuration of
core routers, because forwarding is purely based on MPLS labels. 6PE is a cost effective
solution for IPv6 deployment.
Figure 9: Example of a 6PE Topology within One AS
6PE Control Plane Support
The 6PE MP-BGP routers support:
• IPv4/IPv6 dual-stack
• MP-BGP can be used between 6PE routers to exchange IPv6 reachability
information.
→ The 6PE routers exchange IPv6 prefixes over MP-BGP sessions running over
IPv4 transport. The MP-BGP AFI used is IPv6 (value 2).
→ An IPv4 address of the 6PE router is encoded as an IPv4-mapped IPv6 address
in the BGP next-hop field of the IPv6 NLRI. By default, the IPv4 address that is
used for peering is used. It is configurable through the route policies.
→ The 6PE router binds MPLS labels to the IPv6 prefixes it advertises. The SAFI
used in MP-BGP is the SAFI (value 4) label. The router uses the IPv6 explicit
null (value 2) label for all the IPv6 prefixes that it advertises and can accept an
arbitrary label from its peers.
Fig_30
2001:0620
v4
v6
v6
145:950.0
2001:0621
2001:0420
v6
v6
2001:0421
PP PP
PP PP
6PE 6PE
6PE 6PE
IPv4
MP-BGP sessions
MPLS
CE
Dual Stack IPv4-IPv6 routers Dual Stack IPv4-IPv6 routers
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