Re: is ipv6 fast, was silly Redeploying

[Owen DeLong via NANOG <nanog () nanog org>]

> On Nov 22, 2021, at 02:45 , Masataka Ohta <mohta () necom830 hpcl titech ac jp> wrote:
>
> Mans Nilsson wrote:
>
> > Not everyone are Apple, "hp"[0] or MIT, where initial
> > allocation still is mostly sufficient.
>
> The number of routing table entries is growing exponentially,
> not because of increase of the number of ISPs, but because of
> multihoming.

Again, wrong. The number is growing exponentially primarily because of the
fragmentation that comes from recycling addresses.

> As such, if entities requiring IPv4 multihoming will also
> require IPv6 multihoming, the numbers of routing table
> entries will be same.

There are actually ways to do IPv6 multihoming that don’t require using the
same prefix with both providers. Yes, there are tradeoffs, but these mechanisms
aren’t even practical in IPv4, but have been sufficiently widely implemented in
IPv6 to say that they are viable in some cases.

Nonetheless, multihoming isn’t creating 8-16 prefixes per ASN. Fragmentation
is.

> > Your reasoning is correct, but the size of the math matters more.
>
> Indeed, with the current operational practice. global IPv4
> routing table size is bounded below 16M. OTOH, that for
> IPv6 is unbounded.

Only by virtue of the lack of addresses available in IPv4. The other tradeoffs
associated with that limitation are rather unpalatable at best.

Owen