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JunosE 11.2.x BGP and MPLS Configuration Guide
Connecting IPv6 Islands Across IPv4 Clouds with BGP
Figure 110: IPv6 Tunneled over MPLS-IPv4
476
If you have not upgraded your core to IPv6, you can still provide IPv6 services to customers
by connecting remote IPv6 islands across IPv4 clouds by means of MP-BGP and MPLS.
An IPv6 island is a network employing IPv6 addressing, such as a customer site. The IPv4
cloud consists of the PE–P–PE core.
NOTE: You must configure an IPv6 interface in the parent VR for this feature to work.
Consider Figure 110 on page 476. Each customer site is connected by means of a CE router
to a PE router. The PE routers in this implementation are referred to as dual-stack BGP
(DS-BGP) routers because they run both the IPv6 and IPv4 protocol stack.
The PE routers learn IPv6 routes using MP-BGP over TCPv4 or TCPv6 from the CE devices.
Alternatively, you can configure IPv6 static routes on the PE routers to reach the customer
IPv6 networks through the CE IPv6 link. You can use any IPv6-enabled routing protocol
to access the CE routers.
Use any MPLS signaling protocol to establish an MPLS base tunnel in the IPv4 core
network. Each PE router runs MP-BGP over an IPv4 stack (MP-BGP/TCP/IPv4). MP-BGP
advertises the customer IPv6 routes by exchanging IPv6 NLRI reachability information
across the IPv4 cloud.
Each PE router announces the IPv4 address of its core-facing interface (the tunnel
endpoint) to its PE peers as the BGP next hop. Because MP-BGP requires the next hop
to be in the same address family as the NLRI, the IPv4 next-hop address must be
embedded in an IPv6 format. The PE router advertises the IPv6 routes as labeled routes
and an IPv6 next hop.
In the topology shown in Figure 110 on page 476, OSPF advertises reachability of the
loopback (10.1.1.1/32 and 10.2.2.1/32) and core-facing (10.10.10.1/32 and 10.20.20.2/32)
interfaces of the PE routers. LDP binds label L1 to 10.1.1.1/32 on the P router.
Router CE 1 establishes an MP-BGP session over TCPv4 to PE 1 and advertises its ability
to reach the IPv6 network 2001:0430::/32. The MP-BGP update message specifies an
Copyright © 2010, Juniper Networks, Inc.
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