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From: Archie Cobbs <archie@whistle.com>
Message-Id: <199902010642.WAA25830@bubba.whistle.com>
Subject: Re: drop packets?
In-Reply-To: <36B53717.2D4B7C8F@research.nokia.com> from Shi Yu at "Feb 1, 99 01:09:43 pm"
To: yu.shi@research.nokia.com
Date: Sun, 31 Jan 1999 22:42:04 -0800 (PST)
Cc: freebsd-net@FreeBSD.ORG
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Shi Yu writes:
> When the IF output queue is full, the if_output simply drop the
> packet!??

What else are you going to do with it? :-)

> If the IF output queue is often full, why ip stack does not get feedback
> from the driver and buffer the packets so that less packets are dropped
> ?

I think ip_output() will return ENOBUFS, if anybody's listening.

Anyway, the flow control problem was explicitly left *out* of
the specification of IP packet delivery. IP packet delivery
is only "best effort".. and that's exactly what you get.

Higher layer protocols are supposed to deal with flow control
themselves. For example, TCP.

-Archie

___________________________________________________________________________
Archie Cobbs   *   Whistle Communications, Inc.  *   http://www.whistle.com

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