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Cell Relay Retreat>List Archive>month:1996-Mar> msg00217



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EE Times on IP over ATM

  • From: schulter@zk3.dec.com
  • Date: Thu, 28 Mar 96 11:40:33 -0500
  • Cc: schulter@zk3.dec.com, murray@pa.dec.com, J.Crowcroft@cs.ucl.ac.uk, ip-atm@nexen.com
  • X-Mts: smtp

On Thu, 28 Mar 96 09:13:04 +0200 Juha Heinanen wrote:

>  like it or not, this is how it is when talk about multi-point to point
>  flows.  atm switch can't handle those without store and forward.  but so
>  far atm forum or itu have not defined mp-to-p atm connections at all,
>  which means that you need to use a real layer 3 device at every point
>  when merging of flows takes place.

True, a MP-P circuit would have to do this to handle AAL5 packets.  But
if it did, could it then offer the same QoS guarantees currently offered
by the P-P and P-MP connections?  How is bandwidth and QoS defined in
a circuit with multiple senders and a single receiver?  I think there's
more involved that just keeping the packets together.

Also, I don't think you would need a layer 3 device at every merge point.
All you really need is something above the SAR layer that relays AAL5 SDUs.
This would not have to have any layer 3 awareness.  All that needs to be done 
is to re-assemble AAL5 SDUs and relay them out on the appropriate hop to the 
next switch (or next VC).  This is basically what an MCS is.
 
 --- pete

------------------
Peter Schulter					schulter@zk3.dec.com
Digital UNIX Networking				voice (603) 881-2920
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