On 12/11/2019 09:21, Paolo Abeni wrote:
On Mon, 2019-11-11 at 13:50 -0800, Peter Krystad wrote:
> Hi Paolo -
> On Mon, 2019-11-11 at 17:53 +0100, Paolo Abeni wrote:
>> since such option will always fit the tcp header, module bugs.
thnx! Hopefully comment should be dropped when squashing ;)
> How is it guaranteed that it will always fit, now and in the future?
TCP option space must accomodate tstamp (12 bytes) and MPTCP options.
AFAICS DSS, MP_CAPABLE and MP_JOIN are mutually esclusive, and the
bigger is DSS with 64 bytes ack/seq and csum with a total of 28 bytes -
which fit the TCP option space.
Additional MPTCP options (ADD/DEL_ADDR/PRIO/FAIL/FASTCLOSE/...) can
indeed run out of space, but that failure is not fatal (do not break
the connection nor causes fallback) and is handled gracefully - no
WARN, just omit the option. Additionally we could increment some MIB
When you say that the option is omitted, do you mean that the option is
sent in the new (dedicated?) ACK packet or dropped/never sent? :)
Matthieu Baerts | R&D Engineer
Tessares SA | Hybrid Access Solutions
1 Avenue Jean Monnet, 1348 Louvain-la-Neuve, Belgium