From: Tore Anderson <tore@fud.no>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "Maciej Żenczykowski" <maze@google.com>,
"David Miller" <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
"Tom Herbert" <therbert@google.com>
Subject: Re: [PATCH net-next] ipv6: RTAX_FEATURE_ALLFRAG causes inefficient TCP segment sizing
Date: Thu, 26 Apr 2012 12:32:17 +0200 [thread overview]
Message-ID: <0e135d034e75f56cb6d5318595c17023@greed.fud.no> (raw)
In-Reply-To: <1335350667.3274.53.camel@edumazet-glaptop>
* Eric Dumazet
> Yes, in fact we are going to keep the allfrag feature, and arm it if
> we
> receive an mtu < 512.
One thing to think about if you go down this path is to keep track of
the PMTU received in the ICMPv6 PTB. If you activate the allfrag feature
on a destination because you received a PTB with PMTU=400, it's not
useful to include the Fragmentation header in packets <400 bytes in
size, for example.
With the current code, even tiny packets without any L4 payload (e.g.
TCP SYN/ACK) will have the Fragmentation header added. That's not
optimal, but necessary since the current code does not keep track of the
actual PMTU if it is <1280 as far as I can tell (instead it discards the
received PMTU value, clamps the effective PMTU to 1280, and enables
allfrag).
Tore
next prev parent reply other threads:[~2012-04-26 10:32 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-24 17:37 [PATCH net-next] ipv6: RTAX_FEATURE_ALLFRAG causes inefficient TCP segment sizing Eric Dumazet
2012-04-24 19:49 ` Maciej Żenczykowski
2012-04-24 20:10 ` Eric Dumazet
2012-04-24 21:50 ` Maciej Żenczykowski
2012-04-24 21:51 ` Maciej Żenczykowski
2012-04-25 5:32 ` Eric Dumazet
2012-04-25 7:34 ` Maciej Żenczykowski
2012-04-25 9:20 ` Tore Anderson
2012-04-25 9:38 ` Eric Dumazet
2012-04-25 9:51 ` Tore Anderson
2012-04-25 9:52 ` Maciej Żenczykowski
2012-04-25 10:02 ` Eric Dumazet
2012-04-25 18:39 ` David Miller
2012-04-25 9:48 ` Maciej Żenczykowski
2012-04-25 10:04 ` Tore Anderson
2012-04-25 10:15 ` Eric Dumazet
2012-04-25 10:30 ` Maciej Żenczykowski
2012-04-25 10:44 ` Eric Dumazet
2012-04-26 10:32 ` Tore Anderson [this message]
2012-04-25 10:45 ` Tore Anderson
2012-04-25 11:02 ` Maciej Żenczykowski
2012-04-25 11:49 ` Tore Anderson
2012-04-25 11:55 ` Maciej Żenczykowski
2012-04-27 4:03 ` David Miller
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