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Service Provider IPv6 Deployment: FAQs from Live Webcast




Read the bioSalman Asadulah (CCIE# 2240) is a Cisco Distinguished Engineer and also serves as IPv6 forum fellow,Broadband Forum ambassador, and co-chair of the IPv6 Education Certification Program.He has been working with large-scale IP and multiservice network and technologies for more than 15 years. A frequent speaker at key industry events and conferences who represents Cisco in industry panel discussions and technical platforms, Asadullah influences technology directions and decisions with Cisco business units and customers and the Internet community at large. He is a coauthor and contributor to IETF RFCs/IDs and has written three Internetworking books,Cisco CCIE Fundamentals: Network Design & Case Study, PDIO of the IPT Networks, and Deploying IPv6 in Broadband Access Networks. Asadullah holds a bachelor of science degree in electrical engineering from the University of Arizona and a master of science degree in electrical engineering

from the University of Kansas.



The following experts were helping Salman to answer few of the questions asked during the session: Adriana Vascan, Andrew Yourtchenko, Wen Zhang, Srinivasa Neppalli, and Luc De Ghein. Adriana, Andrew and Luc are support engineers and have vast knowledge in IPv6 related topics.


You can download the slides of the presentation in PDF format here. The Complete Recording of this live Webcast can be accessed here.


IPv6 General Questions

Q. Which Operating System supports IPv6?

A. Windows, Linux and almost all OS support IPv6 these days, including Android and Apple.


Q. Is there any design guide for deploying IPv6, in terms of comarison with IPv4 VLSM and use of NAT?­

A. In general with IPV6, the principles are similar to IPv4 VLSM. NAT is avoided generally, since the 1:1 mapping does not provide the state that is responsible for the unidirectional behavior that contributes to security.


Q. How about allocating address blocks lower than /48?

A. Generally speaking, less than /64 is not considered good practice.


Q. How will i get IPV6 addresses assigned to my devices? Do i need a DHCP Server?

A. If there is an IPv6 capable router, they WILL get an address! No DHCP needed except to pick up DNS server info, but it will share that info as learned from DHCPv4.


Q. Can i run an internal IPv6 network and just have it get translated to IPv4 rather than getting an IPv6 connection ?

A. Yes, the deprecated NAT-PT and the new NAT64 will let you do that, but you lose the end-to-end promises of IPv6 connectivity and still have a stateful NAT box no better than your current NAT44. However, NAT64 can be a useful stepping stone to make your IPv4 infrastructure visible to the IPv6 Internet.


Q. What is the easiest way to get IPv6 connectivity for my company?

A. Use your ISP if they have it, otherwise a free tunnel from a Tunnel broker. LISP is also an option.


Q. How widely adopted is IPv6?

A. It’s picking up fast where certain technical communities it has leaped up – such as SP and large enterprise, universities and DoD networks; more trade shows do IPv6, more networks support IPv6 – latent IPv6 stacks will light up when the network is enabled.


Q. What precautions do i need to take on my Firewall if i allow IPv6?

A. RFC4980; make sure NOT to block ICMPv6, host firewalls are pretty good.


Q. I hear the US Government is requiring the use of IPv6, Does this mean we will need IPv6 to reach Government sites?

A. Not at all, they use dual stack. However, increasingly they will demand suppliers provide websites/content and connections via IPv6.


Q. I am an enterprise customer and need IPv6 internet connectivity from ISP, What should I be asking ISP?

A. Please reffer: .


Q. What precautions do i need to take on my Firewall if i allow IPv6?

A. RFC4980; make sure NOT to block ICMPv6, host firewalls are pretty good.


Q. How to calculate maximum number of users that can use a solution of CGN and how many user would use same IP?

A. It depends on usage pattern with subscriber base. So the first step is to determine current usage of different ports within the network in form of number of ports vs number of subscribers. Having these numbers will allow planning for capacity of CGN.


Q. Where can i find more details about Cisco's CGv6?

A. Please refer:


IPv6 and MPLS


Q. What is recommended in an MPLS network, sharing RR with with IPv4 network via IPv6 address-family or using seperate RRs for IPv6 VPN?

A. General recommendation is separation, however there are quite a few variables it depends on like current load on RRs,, number of routes etc.


Q. If there are no P router and all P routers provide PE functionality, does this have any bearing on deploying a 6PE or 6VPE solution?

A. As long as MP-BGP sessions are there between PEs, it should work fine.


Q. Where can i find more details on Cisco's MPLS 6PE implementation?

A. Please refer:


Q. Where can i find more details about Cisco's MPLS 6VPE implementation?

A. Please refer:


Q. It is seen that other vendors are generating IPv6 explicit label 2 to do ip lookup rather than doing MPLS switching at egree mode?

A. Multiple approaches which are available even 6PE and 6VPE are not only relevant MPLS. It can be done on IPSEC, GRE, L2TP. Most profitable is to look into it and see how SP have deployed large scale. Most SP have used either 6PE and 6VPE for providing scalable solution for their MPLS network.



IPv6 and Multicast


Q. What about Multicast and IPv6? Is there a special address-family IPv6 MDT?

A. See the following document on configuring IPv6 Multicast VPN:



Related Information


  • Books


Deploying IPv6 in Broadband Access Networks - Adeel Ahmed, Salman Asadullah, John Wiley & Sons Publications®

Deploying IPv6 Networks - Ciprian Popoviciu, Patrick Grossetete, Eric Levy-Abegnoli, Cisco Press®

IPv6 Security - Scott Hogg, Eric Vyncke, Cisco Press®

IPv6 for Enterprise Networks - Shannon McFarland, Muninder Sambi, Nikhil Sharma, Sanjay Hooda, Cisco Press®


  • WebSites


IPv6 Support Community

Slides from the Live Webcast

CCO IPv6 Main Page

Cisco Network Design Central

The Internet Engineering task force

IPv6 Forum