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Date: Thu, 7 Mar 2002 15:32:33 -0500 (EST)
From: Robert Watson <rwatson@freebsd.org>
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Subject: kern/35645: Layer 2 switching using default router of "self" broken
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>Number:         35645
>Category:       kern
>Synopsis:       Layer 2 switching using default router of "self" broken
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Mar 07 12:40:01 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     Robert Watson
>Release:        FreeBSD 5.0-CURRENT
>Organization:
NAI LAbs
>Environment:
System: FreeBSD fledge.watson.org 4.5-PRERELEASE FreeBSD 4.5-PRERELEASE #0: Fri Dec 21 21:55:59 EST 2001 robert@fledge.watson.org:/usr/obj/data/fbsd-stable/src/sys/FLEDGE i386

>Description:

Many network stacks use a default route of the local IP address to
represent a switch model in which all packets destined for the default
route are handled by attempting direct link-layer delivery to the
destination over the local interface associated with the IP address.
As a result, some network configurations provide the same IP address
for use both as the host address and the default router via DHCP,
which on FreeBSD results in an inability to send packets off the
local network segment.

Bill Fenner suggests that the FreeBSD stack wants:

   route add default -interface foo0

Instead of use of the IP address, and that the dhclient script should
do the mapping to the appropriate FreeBSD incantation.

>How-To-Repeat:
>Fix:

This is probably an example of a common IP stack quirk being assumed
and propagated to hosts where it's not true.  However, it means that
FreeBSD doesn't work "out of the box" in some switched network
environments.

>Release-Note:
>Audit-Trail:
>Unformatted:

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