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BTs 21st Century Network Fails to Support Crucial IPv6 Standard

Posted: 10th Oct, 2008 By: MarkJ
BT has shockingly confirmed that its new 21st Century Network (21CN) infrastructure does not support the crucial IPv6 protocol, which is kind of important because it's now a well established fact that existing IPv4 addresses are in decline and could run out entirely by 2011.

For those not in the know, an IPv4 address is assigned to your computer each time you go online (e.g. It is a unique online identifier made up of four number groupings and allows you to communicate with other computers around the world; not unlike a phone number for voice calls.

Sadly you can only have so many IPv4 addresses and as a result IPv6 was designed, which are not only longer but also more secure by design. They are 128bits long, written in hexadecimal and separated by colons; for example:


The problem was first noticed by UK ISP Andrews & Arnold (AAISP) yesterday afternoon, which only spotted the lack of support because of a bug in CISCO equipment used by BT, which is affecting use of IPv6 for some of AAISP's customers:

AAISP Blog Post: The next generation internet protocol IPv6 which has been specified since 1998 and is increasing used within the internet and corporate networks is not "supported" by BT's wholesale broadband products.

Even though BT recently launched so called "21st Century Network" products using new fast ADSL2+ links, BT have today stated that "BT currently supports IPv4 on it's Broadband products and does not support IPv6".

The specification for BT's new 21CN products is clear that it allows ISPs to pass packets to and from their end users using point to point protocol (PPP) which would allow ISPs to offer IPv6.

The whole issue has come about because of a bug in CISCO equipment which BT use which is affecting use of IPv6 for some of AAISP's customers. It only affects some of BT's network. Even though we believe this bug was identified and fixed by CISCO a long time ago, BT appear to be refusing to rectify the problem, preferring to simply say they do not support IPv6.

AAISP provide IPv6 services natively and via IPv4, and have done for many years. Tunneled IPv6 works in all cases, and native IPv6 works in some cases where this bug is not affecting it. In some ways the issue is more commercial than technical - IPv6 mostly works, but BT appear to be saying that if it stops working then they won't fix it.

"We have asked BT to formally confirm they will pass all PPP packets on the 21CN network as per BT's specifications, which would allow native IPv6."

Considering the importance of BTs market position and its 21CN network, we're more than a little concerned at its lack of support for IPv6, which should be an essential consideration for any new network developments. IPv6 has been around for a decade and there's really no excuse for not supporting it on such key infrastructure.

However, BT have told AAISP that the provider can submit a formal 'Statement of Requirements' for the service, which would allow BT to fully evaluate the request. In the meantime AAISP will use alternative methods to resolve the problem. It will be interesting to see whether BT is still towing this same line come 2011. Credits to Thinkbroadband for spotting the news.
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