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v4 routes between v6 peering

Dear all,

I want to establish ipv6 peering between router "a" and router "b", but behind these routers there are v4 routes. Now how can I exchange v4 routes traffic over v6 peer ??

                      router-a ------  ipv6 cloud ------ router-b
router-a v4 internal routes                        router-b v4 internal routes

please, suggest me .

Thank you,


11 Replies 11


You need to configure IPV6 tunnel over IPV4.

find the article it will explain and give you clear cut picture about this,




Oh! I think this technique ( the given reference) is allows to connect IPv6 sites over the IPv4 backbone. Actually, I am looking to allows legacy v4 sites over v6 cloud, how ??

Best choice, use v4 backbone to simplify and avoid MTU issues.

Otherwise, tunnel v4 over v6.

Hi Paolo,

Thank you for the response, well my requirement is to enable v6 peering. Because we are planning to migrate our legacy v4 peering with v6.
Could you please, help me with the configuration example of v4 over v6 tunneling.

Thank you,


Refer to the documentation for that.

Be aware, if you press migration to v6 before real need and user demand, you will suffer all the disavantages, but enjoy none of the promised benefits.

Also recommend you do not refer to IP v4 as "legacy", as you would suscitate hilarity in any network professional.


I have got many documents related to 4to6 tunnelling, but still not able to get detail about v4 over v6 tunnelling, I am sorry if I am not getting you! Could you please provide me relevent docs/URL. Your help will be really appreciated.

Thank you,


Considering you evident lack of experience in this profession  I recommend you stay with basic networking until you become more proficient.

You risk to cause major malfunction otherwise. For example, unnecessarily killing MTU on an otherwise perfectly capable circuit.


Very well, thank you for you advice. I am testing v6 peering in my test lab before jumping in my realy network.

Thank you,


Hello Uttam,

Paolo is right: exchanging IPv4 routes over an IPv6 BGP connection is only one aspect of the network change you would like to do.

You need to provide a correct forwarding path for IPv4 packets over an IPv6 backbone.

Unfortunately up to now MPLS works well combined with IPv4 ( no LDP support over IPv6 up to now as far as I know)

An IPv4/MPLS backbone would be your best choice: using private IPv4 addresses on network infrastructure should not be so "legacy" (it is what most ISP and big enterprises are doing now).

Using point to point GRE tunnels could open scalability issues, MTU issues and/or performance issues when dealing with fragmentation and reassembly.

Hope to help


Hi Guiseppe,

Initially, I don’t have any plan to upgrading my existing v4 MPLS backbone, but there can be customers requirement for v6 peering (v6 between PE and CE). I should have a proper plan before deploying v6 peering as Paolo has already suggested.

My current requirement is peering v6 with IX. Few of our IX members are migrating their network v4 to v6 in order to facilitated with IX members we have to deploy or peer v6 and there will be little fun for me as I am going to deploy first time.
And of course in coming days it will be a requirement for the network as it grows.

Thank you,



What is the required software and hardware to have v6 tunnel (tunnel source and destination is ipv6).

I have the Cisco-7200 series router. Does it supports V6 tunnel ?.  The document says about the required sw, but not hw.  So I hope, The feature does not need any specific hardware. please let me know otherwise.


Prabakaran A

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