[rssac-caucus] MTU, MSS and Frag

[Akira Kato]

> I propose RSSAC caucus explore an understanding of the MTU, MSS and
> fragmentation behaviour of all instances of the roots, in IPv6 and
> IPv4.

Just for your information, bind-9.11.0 (I don't know when, but at
least from -P1) set 1220 to MAX TCP Segment size, regardless of the IP
version being used (see at around line 3701 of
lib/isc/unix/socket.c). This may reduce the efficiency of TCP
transaction a little bit, but will cause no harm.

We may need some more discussion to define a correct way in general
(not limited to DNS case) how we can handle TCP segment size.  We may
able to control it with IPV6_USE_MIN_MTU and TCP_MAXSEG, however, each
application must set appropriately. But this may not a business of
RSSAC caucus.

-- Akira Kato