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Date: Sun, 18 Aug 2013 23:12:41 GMT
From: Joe Holden <joe@rewt.org.uk>
To: freebsd-gnats-submit@FreeBSD.org
Subject: Routes not updated on mtu change
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>Number:         181388
>Category:       kern
>Synopsis:       [route] Routes not updated on mtu change
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-net
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Aug 18 23:20:00 UTC 2013
>Closed-Date:    Tue Aug 20 01:09:17 UTC 2013
>Last-Modified:  Tue Aug 20 01:09:17 UTC 2013
>Originator:     Joe Holden
>Release:        HEAD
>Organization:
Pseudo Networks Limited
>Environment:
>Description:
As per post to the list: http://lists.freebsd.org/pipermail/freebsd-net/2013-August/036376.html
>How-To-Repeat:
* Increase mtu on an interface
* Try and send packets bigger than existing mtu
* Receive message too large error
* See that route get returns old mtu until the interface is set down and up
>Fix:


>Release-Note:
>Audit-Trail:
Responsible-Changed-From-To: freebsd-bugs->freebsd-net 
Responsible-Changed-By: linimon 
Responsible-Changed-When: Mon Aug 19 00:59:13 UTC 2013 
Responsible-Changed-Why:  
Over to maintainer(s). 

http://www.freebsd.org/cgi/query-pr.cgi?pr=181388 

From: Julian Elischer <julian@elischer.org>
To: bug-followup@FreeBSD.org, joe@rewt.org.uk
Cc:  
Subject: Re: kern/181388: [route] Routes not updated on mtu change
Date: Mon, 19 Aug 2013 14:57:22 +0800

 The problem is that this is not as simple as it seems.
 The route MTU MIGHT have been set by something other than the 
 interface MTU
 in the first place.
 The interface MTU is a default for the route MTU but is not the only 
 source.
 This actuall bit me a couple of days ago when I was wonderign why my 
 interface was not sending 9K packets..  turns out you need to do 
 'ifconfig_xn0="DHCP mtu 9000"' in order to have your dncp
 configured interface routes  have the right size.
 
 so, I'm agreeing with you , but noticing that there are complications.
 
 
State-Changed-From-To: open->closed 
State-Changed-By: jmg 
State-Changed-When: Tue Aug 20 01:07:27 UTC 2013 
State-Changed-Why:  
per response on mailing list, this is as designed so that the person 
running the box can control the MTU to specific hosts on the network... 

http://www.freebsd.org/cgi/query-pr.cgi?pr=181388 
>Unformatted:
