 Figure 1 The above shown figure is used for test scenario. Enable IPv6 cef
and ipv6 unicast-routing dual stack, CE and route reflectors. Router 8(CPE Router) is the customer router which is having IPv6 connectivity with 6PE(Router 7) and having a default route towards that 6PE(Router 5).
Below is the configuration of Router 8(CPE Router) Interface Configuration interface Ethernet2/3 description 6PE-R5 facing interface ipv6 address 2001:AAAA::2/64 Default Route Config ipv6 route ::/0 2001:AAAA::1
Below is the configuration of Router 5(6PE Router) which is also Dual Stack
Configuration for VRF vrf definition ABC rd 1:1 route-target export 1:1 route-target import 1:1 ! address-family ipv4 exit-address-family ! address-family ipv6 exit-address-family
Interface Configuration interface Ethernet2/3 description CPE-R8 facing interface vrf forwarding ABC ipv6 address 2001:AAAA::1/64
BGP Configuration router bgp 1 no bgp default ipv4-unicast bgp log-neighbor-changes neighbor 1.1.1.1 remote-as 1 neighbor 1.1.1.1 update-source Loopback0 ! address-family vpnv6 neighbor 1.1.1.1 activate neighbor 1.1.1.1 send-community both exit-address-family ! address-family ipv6 vrf ABC redistribute connected no synchronization exit-address-family Defining VRF in 6PE is little bit different in case of IPv4. In this 6PE VRF, we use vrf definition and under vrf definition we have to add address-family IPv6 and IPv4, otherwise it will not work. This is the troubleshooting tip. The next part in comes in MP-iBGP, instead of VPNv4 we have to use VPNv6 address family for carrying VPN prefixes. I am using VPNv6 because internet is serving in vrf. Otherwise we could use IPv6. (See my recent post of Serving IPv6 without vrf). Router 4 is another 6PE router which is connected to IPv6 internet cloud. Below are the configurations of Router 4 VRF Configuration vrf definition ABC rd 1:1 route-target export 1:1 route-target import 1:1 ! address-family ipv4 exit-address-family ! address-family ipv6 exit-address-family
Interface Configuration interface Ethernet2/3 description Connected towards IPv6 Internet Cloud vrf forwarding ABC ipv6 address 2001::2/64
BGP Configuration router bgp 1 bgp router-id 1.1.1.4 no bgp default ipv4-unicast bgp log-neighbor-changes neighbor 1.1.1.1 remote-as 1 neighbor 1.1.1.1 update-source Loopback0 ! address-family vpnv6 neighbor 1.1.1.1 activate neighbor 1.1.1.1 send-community both exit-address-family ! address-family ipv6 vrf ABC redistribute connected redistribute static no synchronization exit-address-family ! ipv6 route vrf ABC ::/0 Ethernet2/3 2001::1 name Default_Route_Towards_IPv6_Internet_Cloud Below is the output of total number of receiving routes from remote 6PE which is router 4.
 Figure 2 Output of all IPv6 prefixes on Router 5  Figure3 2001:AAAA::/64 is the local directly connected interface with CPE-Router 8. Now see the below output of “show bgp vpnv6 unicast vrf ABC 2001::/64” on Router 5, this is the directly connected route of Router 4 which is connected with IPv6 Internet Cloud.
Router 5 is getting update from Router 4 (1.1.1.4) which is clearly depicting from its BGP router id. See carefully the 6th line which is showing ::FFFF:1.1.1.4. It means during update ::FFFF is being appended in BGP router is which is IPv4 address. The 6PE is getting out VPNv6 label 22.  Figure 4 Now cross verify the VPNv6 remote label. In the given one can see that the next hop is 10.1.1.21 which is IPv4 ip address of backbone.[V] means VPN route and stack is having two labels one is IGP which 20 and another is VPNv6 which is 22.  Figure 5 Again cross verify all the labels and next hop address by using given command Show ipv6 cef vrf ABC 2001::/64  Figure 6 Next hop is 10.1.1.21, IGP label is 20 and VPNv6 label is 22.
Initiate a Ping from Router 8 which is CPE  Trace end to end path  Figure 8 We can see that the inner label 22 which is VPNV6 is remain conserved throughout the IPV4 cloud and lookups are performing on the basics of IPv4 labels which keep on changing at each and every hop. Author Shivlu Jain shivlu@mplsvpn.info http://www.mplsvpn.info |
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