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Re: MAE-EAST Moving? from Tysons corner to reston VA.

  • From: Steven M. Bellovin
  • Date: Fri Jun 16 18:07:46 2000 
In message <[email protected]>, [email protected]
com writes:
>
>
>
>On 06/16/2000 at 11:10:55 AST, John Fraizer <[email protected]> wrote:
>> If I'm not mistaken, 9000bytes is the max.
>
>I don't understand how ethernets, at the MAC layer, can support frames
>greater than 1500 bytes.  Looking at the MAC frame format, we have:
>
>ethernet DIX V2    DA(16 bits), SA(16 bits), type (16 bits), data
>IEEE 802.3         DA(16 bits), SA(16 bits), length (16 bits), LPDU (802.2)
>
>The traditional way to distinguish between the 2 formats depends on the
>length value (in 802.3) being no greater than 1500, and on the type value
>(in DIX) being greater than 0x05dc (1500 decimal).
>
>Assuming you're still going to allow both formats on the same lan, how does
>it work if the length is greater than 1500?

See http://search.ietf.org/internet-drafts/draft-kaplan-isis-ext-eth-02.txt
for one proposal.

		--Steve Bellovin