kern/127052: Still bridge issues - with L2 protocols such as PPPoE

[Helge Oldach]

>Number:         127052
>Category:       kern
>Synopsis:       Still bridge issues - with L2 protocols such as PPPoE
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Sep 02 21:30:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Helge Oldach
>Release:        FreeBSD 6.4-1330 i386
>Organization:
>Environment:

System: FreeBSD localhost 6.4-1330 FreeBSD 6.4-1330 #0: Tue Sep 2 18:34:28 CEST 2008 toor at localhost:/usr/obj/usr/src/sys/HMO i386

>Description:

Since the "MAC inheritance" change in if_bridge (SVN r180140) I observe
loss of connectivity due to ARP timeouts and also layer-2 connectivity
issues.

The change below (and the according MFCs) indeed fixes the ARP bridging
issue, but does not fix layer-2 protocols.

For instance, I run a bridge with a wi0 and an fxp0 interface, while
talking PPPoE over the fxp0 interface simultaneously. I observe that the
change below fixes my IP connectivity issue over the bridge, but PPPoE
is still broken. I still need to change the Ethernet address of bridge0
(disable inheritence of the bridge's MAC address from the first member
interface) to make it work.

So I would suggest that a true fix should be implemented in if_bridge,
not in the IP stack.

The issue applies identically to CURRENT, 7-STABLE and 6-STABLE.



Revision 1.174: download - view: text, markup, annotated - select for diffs
Mon Aug 18 09:06:11 2008 UTC (2 weeks, 1 day ago) by philip
Branches: MAIN
Diff to: previous 1.173: preferred, colored
Changes since revision 1.173: +24 -1 lines
SVN rev 181824 on 2008-08-18 09:06:11Z by philip

Fix ARP in bridging scenarios where the bridge shares its
MAC address with one of its members (see my r180140).

Pointy hat to:  philip
Submitted by:   Eygene Ryabinkin <rea-fbsd at codelabs.ru>
MFC after:      3 days


>How-To-Repeat:

Set up PPPoE over a bridge member interface...

>Fix:

Eygene supplied a patch that supposedly fixes this issue by introducing
a sysctl that makes the former if_bridge behaviour default, and which
must be turned on to enable MAC inheritance. I have not tested this
patch yet.

I wonder what the purpose of MAC inheritance is anyway... Multiple
unicast MACs in one segment sounds pretty odd.
>Release-Note:
>Audit-Trail:
>Unformatted: