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Message-ID: <3A0D26BD.E34BF23A@elischer.org>
Date: Sat, 11 Nov 2000 03:00:13 -0800
From: Julian Elischer <julian@elischer.org>
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To: Wilbert de Graaf <wilbertdg@hetnet.nl>
Cc: wu haijun <haggai.wu@huawei.com>, freebsd-net@freebsd.org
Subject: Re: A question for PPPoE 's MTU:
References: <001f01c04afb$9b6e07a0$1b22690a@huawei.com.cn> <003301c04b9d$2cde51d0$0a00a8c0@alias>
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Wilbert de Graaf wrote:
> 
> Hi Wu,
> 
> I remember this problem when we implemented an IP aggregator behind our
> terminal servers. We configured our servers to respond with packet telling
> the client to start over again and use smaller, not fragmented, ip packets.
> This definitely improved performance. I think this is rfc879 (The TCP
> Maximum Segment Size) related.
> I don't remember how we did it but I believe just setting the MTU on that
> interface to 1492 in your case, and set don't fragment.

I once wrote a module that intercepted all tcp setup packets passing
through the system
and rewrote them to say that the windows and MTUs should be lower.

> 
> - Wilbert
> 
> ----- Original Message -----
> From: wu haijun
> To: freebsd-net@freebsd.org
> Sent: Friday, November 10, 2000 1:50 AM
> Subject: A question for PPPoE 's MTU:
> 
> Hi:
> 
> The MTU of PPPoE is 1492 Bytes. But if the PPPoE Server receives IP  packets
> from the WAN and the packets's will be always 1514 Bytes,so the Server must
> fragment the Packets to fit in the PPPoE packets ,and this will degrade the
> performance of the Server.
> Why not suggest that PPPoE header didn't be included in the MTU
> calculation,just like VLAN encapsulation?
> 
> Regards
> 
> Wu Haijun
> Huawei Tech. Corp. LTD  in CHINA
> Senior Firmware Engineer
> 
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-- 
      __--_|\  Julian Elischer
     /       \ julian@elischer.org
    (   OZ    ) World tour 2000
---> X_.---._/  presently in:  Budapest
            v


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