Re: Link MTU option ignored in IPv6 router advertisements



Thanks, bug filed:

https://bugzilla.gnome.org/show_bug.cgi?id=738104

On Fri, Oct 03, 2014 at 12:01:38PM -0500, Dan Williams wrote:
On Fri, 2014-10-03 at 11:36 -0400, Chuck Anderson wrote:
I'm not sure if this is a kernel thing or a NetworkManager thing.  Did
something change in how IPv6 router advertisements are handled by
NetworkManager in Fedora 20?

I think it's a NetworkManager thing.  We'll fix it.

Dan

On my Fedora 20 system, the Link MTU option recevied from IPv6 router
advertisements is not being applied to the interface configuration:

kernel-3.16.2-200.fc20.x86_64
NetworkManager-0.9.9.0-44.git20131003.fc20.x86_64

cat /proc/sys/net/ipv6/conf/wlp2s0/mtu 
1500

On my Fedora 19 system, this is working:

kernel-3.14.18-100.fc19.x86_64
NetworkManager-0.9.8.8-2.fc19.x86_64

cat /proc/sys/net/ipv6/conf/p4p1/mtu
1480

In both cases, the RA has the Link MTU option:

sudo rdisc6 -1 wlp2s0
Soliciting ff02::2 (ff02::2) on wlp2s0...

Hop limit                 :           64 (      0x40)
Stateful address conf.    :           No
Stateful other conf.      :           No
Mobile home agent         :           No
Router preference         :       medium
Neighbor discovery proxy  :           No
Router lifetime           :          300 (0x0000012c) seconds
Reachable time            :  unspecified (0x00000000)
Retransmit time           :  unspecified (0x00000000)
 Prefix                   : 2001:xxxx:xxxx:1::1/64
  On-link                 :          Yes
  Autonomous address conf.:          Yes
  Valid time              :          300 (0x0000012c) seconds
  Pref. time              :          300 (0x0000012c) seconds
 MTU                      :         1480 bytes (valid)
 Source link-layer address: 68:7F:74:xx:xx:xx
 from fe80::6a7f:74ff:fexx:xxxx

I need this option because my IPv6 router uses a HE.net tunnel which
adds 20 bytes of overhead for the 6in4 encapsulation, and many sites
break PMTUD which causes those sites to hang.


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]