Subject: (IPng 6525) Re: Packet Loss (was Re: Host Fragmentation

From: [email-masked]
Date: Thu, 24 Sep 1998 20:50:28 EDT

In a message dated 9/24/98 10:17:22 AM Eastern Daylight Time, [email-masked]
writes:

> >Suppose near the transmitter there is an underpowered (non-wirespeed
>  >router that can't keep up with data being received) when the packets
>  >are small on a large MTU medium.  

>  That's sort of like putting a Rolls Royce Merlin engine in a Cessna
>  172 airframe and then whining that whenever you start the engine, the
>  torque flips the plane over onto its back.

Not a valid comparison.  Who knows what sort of router might
be used in some portion of the Internent to provide topological
redundancy?   In many configurations, the Cisco
7000 series routers are underpowered because of some serious
design flaws.  There are lots of Cisco 7000 series routers
all over the Internet and as more powerful alternatives become
available they are being moved to network edges or are
being used to provide topological redundancy.

In any case, I described the underpowered router scenario
in order to point out that it is not hard to think of real internet
situations where using TCP segmentation or host fragmentation
can lead to packet loss while network fragmentation would not.
  
>  In other words, if performance is that critical to the application,
>  you have to engineer the whole system (by system I mean the transmitter,
>  the routers, the media, the paths, etc, etc) to meet the goals. 

Almost correct, in terms of the Internet, one engineers that portion
of the system under one's control and provides mechanisms
(like perhaps network fragmentation) for contingencies that
may arise beyond one's control like the sudden kick in of
a back up router that might be underpowered for the modifiable
characteristics of the traffic that needs to be switched.

Joachim Martillo
<A HREF="http://members.aol.com/Telford001/">Telford Tools, Inc.</A> 
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