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From: tinkelman@ccavax.camb.com
Newsgroups: comp.dcom.sys.cisco
Subject: Re: poor inter-area routed DECnet performance (long)
Message-ID: <25934.266f66c4@ccavax.camb.com>
Date: 8 Jun 90 12:50:12 GMT
References: <21919@megaron.cs.arizona.edu>
Organization: Cambridge Computer Associates, Inc.
Lines: 26

In article <21919@megaron.cs.arizona.edu>, Leonard@arizona.edu (Aaron
Leonard) described a problem involving slow throughput between certain
pairs of nodes (in a picture, partially reproduced below).

I can't offer a coherent explanation of the differences you reported, but I
do want to comment on one of your examples, that was the throughput between
endnodes CIRRUS and UAZHE4:

>                      [ UAZHE0   46.437 ]   [ UAZHE4  46.365 ]
>                      [ level II router ]   [    endnode     ]
>                           |                  |
> [ MAGGIE   50.204 ]--(  large bushy bridged   )--[ CIRRUS  50.140 ]
> [ level II router ]  ( ethernet <128.196.128> )  [    endnode     ]
... 
>             Note that the lev II routers are NOT the bottleneck;
> traffic that flows between e.g. CIRRUS and UAZHE4, which passes
> thru MAGGIE and UAZHE0, but not thru PANCHO, is quick.  

My comment is that DECnet will use the intermediate level II routers only
to help the two end nodes find each other.  Once the circuit between them
is established, CIRRUS and UAZHE4 will communicate directly with each other.
This means there will be no intermediate DECnet routing *and* max size 
Ethernet packets can be used.
-- 
Bob Tinkelman, Cambridge Computer Associates, Inc., 212-425-5830              
bob@camb.com  or ...!{uupsi,uunet}!camb.com!bob