Going dual-stack, how do apps behave and what to do as an operator (Was: Apple Airport Extreme IPv6 problems?)

michael.dillon at bt.com michael.dillon at bt.com
Wed Sep 19 13:01:50 UTC 2007

> Just stumbled upon this article

>Suggested here is that Dual Stack is more attractive than tunneling. Is
the advise here based on real life experience or is it a matter of what
is good for the goose may not be good for the gander?

The article is written for enterprise network administrators, not for
ISPs. If you are an ISP, the two main options are to dual-stack or to
use MPLS with 6PE. Even if your network does not have an MPLS core
today, you should still consider whether it makes sense to use MPLS with
6PE as your migration path to IPv6. Every network is different so there
is really no panacea here.

As for tunnels, I expect that everybody uses them somewhere in the
network. There are lots of different kinds of tunnels, more than
mentioned in the article. For ISP purposes, you could build an IPv6
overlay network instead of either dual-stacking or MPLS with 6PE. For
small to midsize ISPs this may make a lot of sense. For larger ISPs,
they will likely do some of this to accommodate their 2nd and 3rd tier
PoP locations. The important thing about tunnels is to make sure that
they are well-designed and well-maintained. The most important aspect of
maintaining a tunnel, is making sure that you get rid of it when it is
no longer the best solution.

MPLS is based on tunneling. Lots of broadband access is based on
tunnels. Pseudo-Wire Emulation is based on tunnels.

--Michael Dillon

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