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From: Hannes Frederic Sowa <hannes@stressinduktion.org>
To: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	David Miller <davem@davemloft.net>,
	Francois WELLENREITER <f.wellenreiter@gmail.com>,
	netdev@vger.kernel.org
Subject: Re: [PATCH] ipv6: Limit mtu to 65572 bytes
Date: Fri, 11 Apr 2014 04:57:07 +0200	[thread overview]
Message-ID: <20140411025707.GM27255@order.stressinduktion.org> (raw)
In-Reply-To: <534753D4.6070600@linux-ipv6.org>

On Fri, Apr 11, 2014 at 11:30:44AM +0900, YOSHIFUJI Hideaki wrote:
> Eric Dumazet wrote:
> 
> > We must limit the IPv6 MTU to (65535 + 40) bytes in theory.
> > 
> > In practice, its better to align to a multiple of 4 for optimal TCP
> > performance.
> 
> It is a TCP issue.  We should not limit the mtu to 65532+40.
> I am for 65535+40. Otherwise, other protocol such as UDP cannot
> use full mtu as before.

I have not seen problems with max ipv6 mtu limit of 65535+40 and tcp.

I agree this would be a better approach, and maybe & ~3 the mtu/mss
in tcp code? I assume people expect maximum udp packet sizes working
over loopback?

Greetings,

  Hannes

  reply	other threads:[~2014-04-11  2:57 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-09 19:42 Does IPv6 support Jumbograms ? Francois WELLENREITER
2014-04-09 20:35 ` Hannes Frederic Sowa
2014-04-09 21:41 ` Eric Dumazet
2014-04-09 22:35   ` Hannes Frederic Sowa
2014-04-10  0:36     ` Eric Dumazet
2014-04-10 13:28       ` Hannes Frederic Sowa
2014-04-10 14:01         ` Eric Dumazet
2014-04-10 23:54       ` Hannes Frederic Sowa
2014-04-11  0:40         ` Eric Dumazet
2014-04-11  1:42           ` [PATCH] ipv6: Limit mtu to 65572 bytes Eric Dumazet
2014-04-11  1:58             ` Eric Dumazet
2014-04-11  2:30             ` YOSHIFUJI Hideaki
2014-04-11  2:57               ` Hannes Frederic Sowa [this message]
2014-04-11  3:14                 ` Eric Dumazet
2014-04-11  8:40                   ` David Laight
2014-04-11  8:34                 ` David Laight
2014-04-11  3:20               ` Eric Dumazet
2014-04-11  3:26                 ` YOSHIFUJI Hideaki
2014-04-11  3:30                   ` YOSHIFUJI Hideaki
2014-04-11  3:30                 ` David Miller
2014-04-11  4:20                   ` Eric Dumazet
2014-04-11  4:23                 ` [PATCH v3] ipv6: Limit mtu to 65575 bytes Eric Dumazet
2014-04-11 13:22                   ` Hannes Frederic Sowa
2014-04-11 15:26                     ` Eric Dumazet
2014-04-11 20:48                   ` David Miller
2014-04-11  2:44             ` [PATCH] ipv6: Limit mtu to 65572 bytes Hannes Frederic Sowa

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