Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!think.com!yale.edu!ox.com!math.fu-berlin.de!fauern!faui43.informatik.uni-erlangen.de!eckert
From: eckert@immd4.informatik.uni-erlangen.de (Toerless Eckert)
Newsgroups: comp.dcom.sys.cisco
Subject: Re: Aggregate thru-put of an AGS+
Message-ID: <1991Jun14.181125.18693@informatik.uni-erlangen.de>
Date: 14 Jun 91 18:11:25 GMT
References: <13670001@hprnd.rose.hp.com>
Organization: CSD., University of Erlangen, Germany
Lines: 55

From article <13670001@hprnd.rose.hp.com>, by pugh@hprnd.rose.hp.com (Rex Pugh):
>     __________________________________
>    |              AGS+               |
>    |_________________________________|
>    |               _____             |
>    |              /  Y  \            |
>    |             ^       v           |
>    | Slot0  =0===1===2===3===4===5=  |
>    |         v       ^               |
>    |          \__R__/                |
>    |_________________________________|
>    |                                 |
>    | Ethernet                        |
>    | Stream    Input  Output Drop%   |
>    | -----------------------------   |
>    | Red       14531   9023   38%    |
>    | Yellow    14454   9015   38%    |
>    |           -------------------   |
>    |           28985  18038   38%    |
>    |                                 |
>    | 802.3                           |
>    | Stream    Input  Output Drop%   |
>    | -----------------------------   |
>    | Red       14531    749   95%    |
>    | Yellow    14447    742   95%    |
>    |           -------------------   |
>    |           28978   1491   95%    |
>    |                                 |
>    | SNAP                            |
>    | Stream    Input  Output Drop%   |
>    | -----------------------------   |
>    | Red       14531    749   95%    |
>    | Yellow    14447    742   95%    |
>    |           -------------------   |
>    |           28978   1491   95%    |
>    |_________________________________|

What i don't understand is what the relevance of the numbers is.
Is this meant to measure how fast the box can drop packets ?
Why are there no numbers for which the box had a maximum throughput
WITHOUT dropping packets, you only had this information for the first
two or so diagrams ? The number of packets on the outputs will
most surely be higher for the maximum number of input packets
that the box can forward without dropping packets. From my understanding
(and measurements on different equipment) you can have quite a sharp
negative response onto packet overload on input, so the output rate
can drop rapidly if you overload the box. I don't see this to be a
big problem, because upper layers have to cope with overload anyway, so
a negative characteristic in the router might even speed that process up ?

---

             Toerless.Eckert@informatik.uni-erlangen.de
    /C=de/A=dbp/P=uni-erlangen/OU=informatik/S=Eckert/G=Toerless
             bandwidth - the final frontier.