4000 Router Series MPLS Configuration Guide

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As shown in Figure 61, the IPv6 MPLS L3VPN packet forwarding procedure is as follows:

1. The PC at Site 1 sends an IPv6 packet destined for 2001:2::1, the PC at Site 2. CE 1 transmits the

packet to PE 1.

2. Based on the inbound interface and destination address of the packet, PE 1 finds a matching entry

from the routing table of the VPN instance, labels the packet with both inner and outer labels, and

forwards the packet out.

3. The MPLS backbone transmits the packet to PE 2 by outer label. The outer label is removed from

the packet at the penultimate hop.

4. According to the inner label and destination address of the packet, PE 2 searches the routing table

of the VPN instance to determine the outbound interface, and then forwards the packet out of the

interface to CE 2.

5. CE 2 forwards the packet to the destination by IPv6 forwarding.

IPv6 MPLS L3VPN routing information advertisement

The routing information for a local CE is advertised to the remote CE using the following process:

1. From the local CE to the ingress PE.

The local CE advertises standard IPv6 routing information to the ingress PE over an IPv6 static route,

RIPng route, OSPFv3 route, IPv6 IS-IS route, IBGP route, or EBGP route.

2. From the ingress PE to the egress PE.

After receiving the standard IPv6 routes from the CE, the ingress PE adds RDs and route targets to

create VPN-IPv6 routes, saves the routes to the routing table of the VPN instance created for the CE,

and then notifies MPLS to assign VPN labels for the routes.

Then, the ingress PE advertises the VPN-IPv6 routes to the egress PE through MP-BGP.

The egress PE compares the export target attributes of the VPN-IPv6 routes with the import target

attributes that it maintains for the VPN instance and, if they are the same, adds the routes to the

routing table of the VPN instance.

The PEs use an IGP to ensure the connectivity between them.

3. From the egress PE to the remote peer CE.

The egress PE restores the original IPv6 routes and advertises them to the remote CE over an IPv6

static route, RIPng route, OSPFv3 route, IPv6 IS-IS route, EBGP, or IBGP route.

IPv6 MPLS L3VPN network schemes and functions

IPv6 MPLS L3VPN supports the following network schemes and functions:

• Basic VPN

• Inter-AS VPN option A

• Inter-AS VPN option C

• Carrier's carrier

• Multi-VPN-instance CE