IPv6 6to4 tunnel on stub router

[Alexander Simbun]

Hello all,

I'm wondering if it is possible to do 6to4 tunnel on stub router with only single link to a router which connecting to all remote sites?

I'm curious whether it is possible to do this.

Let me know. Thank you very much.

Alex

[Peter Paluch]

Hi Alex,

Yes, this is possible. However, the IPv6 6to4 address on this tunnel must be derived from your IPv4 address: 2002:ac1f:fffe::1/128. (172=0xAC, 31=0x1F, 255=0xFF, 254=0xFE).

The configuration would then be straightforward:

ipv6 unicast-routing
ipv6 cef
!
interface Tunnel0
 tunnel mode ipv6ip 6to4
 tunnel source 172.31.255.254
 ipv6 address 2002:ac1f:fffe::1/128
!
ipv6 route 2002::/16 Tunnel0

I am not including the IPv4 connectivity configuration here as I assume that this connectivity is already up and running.

Please feel welcome to ask further!

Best regards,
Peter

[Ciro Gustavo Mele]

This tested if it works

Tks.

[Alexander Simbun]

Hello Peter,

Thank you very much for your reply. The IPv6 addresses are just examples to explain my question. I have tested in our lab and it proves to be working. Just wonder if without the stub router and the IPv6 tunnel is configured on gateway router where the connection to the WAN is via MPLS L3 network provided by our ISP. Would that working? I did posted similar issue in this forum before relating to IPv6 tunnelling via MPLS L3 cloud.

https://supportforums.cisco.com/discussion/12696916/ipv6-tunnel-issue-mplsipvpn-cloud

Let me know about this.

Regards,

Alex

[Philip D'Ath]

Yes.

You can do something like this to allow the stub router to auto-configure 6to4 and create a pool where Dialer0 is the outside interface with an IPv4 public address:

ipv6 general-prefix 6to4 6to4 Dialer0
ipv6 unicast-routing
ipv6 cef

interface Tunnel6
ipv6 address 6to4 ::/64 eui-64
tunnel source Dialer0
tunnel mode ipv6ip 6to4
tunnel path-mtu-discovery

interface vlan1

  ipv6 address 6to4 ::1:0:0:0:1/64

You can also then DHCPv6 out the other prefixes to downstream routers.

With regard to the routing - I would use EIGRP with LISP encapsulation and OTP.  This will allow full IPv6 routability over the MPLS network, even though the MPLS provider has no IPv6 support.  If you use this for IPv4 as well you can drop BGP peering with the MPLS provider, as they will be doing nothing more than providing transit for you.

[Alexander Simbun]

Thank you P.dath,

If am not mistaken, tunnel path-mtu-discovery needs to be enable on both sides of the router am I right?

Regards,

Alex

[Philip D'Ath · Accepted solution]

Only if you want two way traffic.  :-)