Messages in this thread |  | | Date | Mon, 4 Nov 1996 11:45:47 -0500 (EST) | From | Ion Badulescu <> | Subject | Re: ifconfig eth0 mtu 2000: SIOCSIFMTU: Invalid argument |
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On Mon, 4 Nov 1996, Michael L. Galbraith wrote:
> > Care to specify what kernel version you're using? > Redface. I noticed the omission right after xmit. 2.0.24 was my victim.
The max 1500 MTU limit on Ethernet is enforced by the kernel since early 2.0.x/late pre-2.0.
> > No, a bug was fixed. 1500 is the maximum MTU for Ethernet. > Bug? I've set the mtu > 1500 on other systems too.
The Ethernet specs allow up to 1500 bytes of data per frame. The IP layer has to fragment large IP packets, so that's where MTU gets used. If you set it to larger than 1500, it _might_ work, but it's not guaranteed to work - the Ethernet layer does not do fragmentation, as it has no idea about IP fragments, so it will pass the large packets along and pray.
But again, the newer kernels don't even let you set an MTU large than 1500 over Ethernet.
Ionut
-- Ionut Badulescu - Columbia College '98 E-mail:ib42@columbia.edu Phone: (212)853-7875 Snail mail: 4A4 Wallach Hall Fax: (212)695-5560 1116 Amsterdam Ave PGP key available on request New York, NY 10027 It is better to keep your mouth shut and be thought a fool, than to open it and remove all doubt.
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