Fw: [e2e] Ethernet Encapsulation

Cannara cannara at attglobal.net
Wed Nov 7 21:20:53 PST 2001


A classical Ethernet II controller will identify end of frame by the lack of
bit transitions, rounded down to a byte bound (eliminating "dribble bits"). 
When it sends frames, they always end (via padding) on byte bounds (on the way
out onto the physical interface).  As as far as data enclosed is concerned,
all higher protocols have lengths included in the frame, or implied by their
agreed-upon PDU sizes.

Alex


Wu Yan wrote:
> 
>  Hi,
>      A possible method might be using the frame delimitation to determine
> the
>  start and end of a frame.
> 
>  Yan Wu
> 
>  Telecommunication Research Center
>  Electrical Engineering Department
>  Arizona State University
> 
> > ----- Original Message -----
> > From: "Tianbo Kuang" <kuang at cpsc.ucalgary.ca>
> > To:
> > Sent: Wednesday, November 07, 2001 10:54 AM
> > Subject: [e2e] Ethernet Encapsulation
> >
> >
> > > Hi,
> > >
> > > Just noticed in Stevens's book that in an Ethernet Encapsulation (rfc
> > > 894) there is no length field. My question is how does the device driver
> > > determine the length of the current frame? This question is also valied
> > > for 802.11b encapsulation.
> > >
> > > Thanks.
> > >
> > > --Tianbo
> > >





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