10 gige experience

Greg Maxwell gmaxwell at martin.fl.us
Thu May 10 12:31:46 UTC 2001

On Fri, 11 May 2001, Chris Wedgwood wrote:

>     Anyone know any good articles on 10GB ethernet? I am specifically
>     intrested if they have removed some of the legacy requirements
>     that hamper gigabit ethernet (such as a default MTU of 1500,
>     half-duplex, etc.)
> Not answering your question, but GigE can use larger frames than 1500
> bytes, however, if you wish to send these outside your network,
> you'll likely need to fragment them this somewhat less useful... of
> course, Jumbo Frames are still useful within your network, but then
> again most switches don't support them[1].

Which is why I said 'default' MTU of 1500. I think it should have been a
requirement of all 100TX devices to be able to accept FDDI sized packets,
a requirement of GIGE to switch FDDI sized packets, etc.. Thats not what

The problem is that there is no graceful way to handle mixed MTU's at that
layer. As a result, the default is to use legacy sized MTUs, which results
in new equpment which can not handle the larger MTUs, resulting in the
further delay of end-to-end jumbogram support.

At some point, they need to draw a line and say that reception and
switching of large >1500 byte packets must be supported and generation of
such packets should be an option. This will finally make is possible for
people to jumbogram enable their networks.

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