BBC News - 'Fresh proposals' planned over cyber-monitoring

Florian Weimer fw at
Mon May 13 20:41:16 BST 2013

* Andrew Cormack:

> If I remember correctly (and it was a *very* long time ago) one of
> the aims of v6 was to reduce the size of routing tables by bringing
> a bit of structure to address allocations. Doesn't mapping v4
> addresses into part of the v6 space mean that the v6 table has to be
> at least as big as the v4 one from day one?

Uhm, correct.

> That may be less of an issue nowadays (the v6 designers presumably
> had in mind the memory limits/costs of routers twenty years ago) but
> it may be one reason why they chose a clean break.

These days, you'd probably extract the IPv4 address and look it up
using the IPv4 forwarding engine because most IPv6 routers have that
as well.  But that's entirely hypothetical.

(IPv6 routing table sizes with hundreds of thousands of prefixes is
still a bit tricky if you want to forward hundreds of millions of
packets per second on a single router.)

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