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Recommended transition solution for ISP:s with enterprise customers?


What would be the recommended solution(s) for ISP:s with enterprises only as customers?

It both needs to support IPv6 and at the same time save IPv4 resources.

Thanks in advance!

4 Replies 4

Phillip Remaker
Cisco Employee
Cisco Employee

In order to best optimize your existing investment, the answer depends on what services you already provide to customers and what their Customer Edcge (CE) devices are like.

Are you providing MPLS transport?  VPN?  Internet access?  Do you provide the CE or does the customer?  Are the CEs uniform or all over the place?

Do you own Channel Banks, DSLAMs or CMTSes, or do you buy last mile transport from someone else?

The quick-and-dirty fix is 6rd, which tunnels IPv6 inside IPv6 using existing IPv4 addressing to form the IPv6 prefixes.  This works best if the IPv4 addresses are static so the IPv6 prefixes can be as well.  You can read a white paper about 6rd here:

If you run MPLS, 6PE and 6VPE might be more useful.  You can read about them here:

But to better answer the question you would need to provide more information.

Thank you for the reply! The customer edge devices are Juniper SRX at this point and the customers are offered services like Internet access and Eth and IP VPN. The entire ISP net is dual stacked.

As for multiplexing, DLSAMS are used.

Hope this provided the information needed, thanks in advance!



There  are many possible choice for a soft transition of the Service Provider:

- Dual-Stack

The SP can run both protocols in the backbone for a while so he can test IPv6 Service by switching some part of the Network to IPv6 Only and see if it is OK. In case there is a problem he can get back to dual-stack, fix the issue and resume its testing until it is Ok and he can allow IPv6 Only.

- It is possible to provide IPv6 Service without upgrading the backbone to IPv6 Immediately using 6RD if the backbone is IPv4 or 6PE /6VPE (I did the dev-test for 6PE and 6VPE for CISCO for 3 years) if the backbone is IPv4/MPLS. This way the SP can start providing both IPv4 and IPv6 without upgrading the backbone. He can then move slowly to IPv6 with a Dual-Stack period not to switch immediately to IPv6 and allow to fallback if soething is not properly configured to work in IPv6 Only.

With 6VPE, the customer benefit of a dual-stack VPN and recently, CISCO has improved the Support of Multicast in MPLS which was main weakness of MPLS based solutions.

Once the SP has migrated to IPv6 Only, it is still possible to offer dual-stack, IPv4 and IPv6 service to its customers using DS-Lite or better, A+P when it will be available as A+P (dIVI-pd based) does not rely on CGN which has a couple of drawbacks for the SPs.

Once the Customer has migrated to IPv6 Only, it is also still possible to access some IPv4 resources (Networks, servers, applications) using NAT64.

I have a presentation for you:

And you will find more on my page:

I will be glad to help you further.

Fred Bovy

15 years ccie #3013

18 years ccsi #33517 (former #95003)

IPv6 Forum Gold Certified Engineer

IPv6 Forum Gold Certified Trainer





Hi Fred, thanks for the reply!

The entire backbone / ISP net is dual stacked.

My concern with the A+P solutions exist because the customer base is enteprises only. Therfore, being provided only part (port range) of an IPv4 adress surely can't support a number of X (40 - 1000) employees?

Very thankful for your response!

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