Re: help with interfaces gr

Geoff Thompson <Geoff_Thompson.ENGIN#u#THREE@engtwomac.synoptics.com> Sat, 07 August 1993 18:13 UTC

Message-Id: <9308071808.AA22461@synoptics.com>
Date: Fri, 06 Aug 1993 20:21:53 -0000
Sender: ietf-archive-request@IETF.CNRI.Reston.VA.US
From: Geoff Thompson <Geoff_Thompson.ENGIN#u#THREE@engtwomac.synoptics.com>
Subject: Re: help with interfaces gr
To: Greg Fisher <fisher@tinton.ccur.com>, snmp@psi.com, enet_mib@ftp.com, anil@levers.enet.dec.com

        Reply to:   RE>>help with interfaces gro
The dot3 preamble plus SFD is 8 bytes when transmitted by an "interface".  That
can change as it goes through a network.  You lose a little going through AUIs,
transceivers and cables.  You gain a little going through repeaters.  The
maximum you can gain going through a legal network is 30 bits.

Geoff Thompson 
Vice chair 802.3
--------------------------------------
Date: 8/6/93 8:15 PM
To: Geoff Thompson
From: Greg Fisher
[ Anil writes ]
> 
> Here are some answers.  By the way, the enet_mib@ftp.com mailing list
> would be a better place to ask these questions.
> 
...
> 
> > 8) Although the MIB says that ifInOctets should include "framing
characters",
> > my hardware doesn't provide any indication of the length of the received
> > preamble.  Should I ignore the preamble or add an estimate (8 bytes per
> > packet) to the total count?
> 
> Don't include preamble.
Why not?

The way I thought about it was that the preamble was using available
bandwidth on account of a given transmission, and so represents part of the
"framing" overhead which was being referred to in rfc1213.

BTW, I thought the dot3 preamble was 7 bytes. No?  Does it vary?
...
> Anil

Greg Fisher

Re: help with interfaces gr Geoff Thompson