Bug 181388 - [route] Routes not updated on mtu change
Summary: [route] Routes not updated on mtu change
Status: Closed FIXED
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: Unspecified
Hardware: Any Any
: Normal Affects Only Me
Assignee: freebsd-net (Nobody)
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-08-19 00:20 UTC by Joe Holden
Modified: 2013-08-20 02:09 UTC (History)
0 users

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Description Joe Holden 2013-08-19 00:20:00 UTC 
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
Comment 1 Mark Linimon freebsd_committer freebsd_triage 2013-08-19 01:59:13 UTC 
Responsible Changed
From-To: freebsd-bugs->freebsd-net

Over to maintainer(s).
Comment 2 Julian Elischer 2013-08-19 07:57:22 UTC 
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.
Comment 3 John-Mark Gurney freebsd_committer freebsd_triage 2013-08-20 02:07:27 UTC 
State Changed
From-To: open->closed

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...