Experiences with IPv6 and Routing Efficiency

Saku Ytti saku at ytti.fi
Sun Jan 19 18:55:56 UTC 2014

On (2014-01-19 08:08 +0400), Mukom Akong T. wrote:

> How prevalent is this problem? There might be not point fixing a problem
> with a 0.2% probability of occurring, especially as it might be cheaper to
> detect and fix the errors at the application layer.

I have no data on prevalency. But just this week we caught issue where ingress
PE was mangling packets on IP2MPLS encap and calculating correct FCS on the
mangled frame.
All egress PE routers logged IP checksum error, it was very rare, maybe 1 per
30min on average. If it was IPv6, no error would have been logged, and
customers would receive their share of these, <1 per month per customer, for
sure, we would have never have found this issue in IPv6 network.

> Could you please explain how broadcast is better than solicited node
> multicast. In any case we aren't getting round that for now and it is
> deeply imbedded in NDP. I am interested in your negative experiences with
> solicited node multicasts.

It requires group state in switches, potentially 16M groups, switches
typically support few thousands and only populate them in SW (but forward on
HW once built).
Several attack vectors there.

> Just because you can have 2^64 possible hosts on a LAN still doesn't mean
> we through principles of good LAN design out the door. :-) So I'd say it's
> rather the fault of shoddy network design rather than address policy.

Nick covered this, thanks.


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