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Date:      Mon, 15 Oct 2001 15:49:19 -0700 (PDT)
From:      Archie Cobbs <archie@dellroad.org>
To:        Mike Tancsa <mike@sentex.net>
Cc:        freebsd-net@FreeBSD.ORG
Subject:   Re: strange results with increased   net.inet.ip.intr_queue_maxlen
Message-ID:  <200110152249.f9FMnJJ33076@arch20m.dellroad.org>
In-Reply-To: <5.1.0.14.0.20011012121150.072325d0@marble.sentex.ca> "from Mike Tancsa at Oct 12, 2001 12:13:59 pm"

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Mike Tancsa writes:
> >If the forwarding path is maxed out, then it is the application layer's
> >responsibility to back off (think TCP).
> 
> Is it better for the networking layer to deal with this (potentially 
> introducing some latency) as opposed to letting the application ?

Oops, can substitute "transport" for "application"..

But no, the network should just do "best effort".. that is, unless
you are a telco type in which case, go back to your X.25 :-) This
is a religious issue to some degree, but in practice the war is over
and the Internet won (vs. the telco way of doing things).

There is probably a good paper somewhere outlining the "best effort"
philosophy but I don't know what it is. Another way to look at it
is intelligence in the leaf nodes rather than in the network. This
is one of the central idea of the Internet dating back to a long
time ago. I guess the other big idea is packets instead of dedicated
circuits (which hog resources).

> >Pinging is an excellent way to determine latency.
> 
> I guess then its only at the "worst case" where I would see the added 
> latency as I dont see any difference by adjusting the queue size.

Yes, you wouldn't notice a difference except when the queue is
full all the time (the "worst case").

-Archie

__________________________________________________________________________
Archie Cobbs     *     Packet Design     *     http://www.packetdesign.com

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