[Xorp-hackers] Committed a fix for MTU and carrier detect on older systems.

[Ben Greear]

This was pushed to the xorp.ct tree just now.  I'm not sure how much of
this exists in svn and/or 1.6, but likely a bit of it as I don't recall
ever messing with the carrier-detect logic before in xorp.ct.

     fea:  Fix link & MTU detection on funky systems.

     Older kernels did not include MTU in the netlink message, so
     add a work-around to look at /sys/class/net/[dev]/mtu file for
     MTU.  If that fails too, default to 1500.

     Standard Carrier detection doesn't work on all NICs, especially
     not open-vz virtual NICs from 2.6.18-ish kernels.  Add work-around
     to look at /sys/class/net/[dev]/carrier if all other methods fail.

     In addition, old code would return failure if any of several methods
     failed.  This patch will try each method in series and only return
     failure if ALL of them fail.

     Big thanks to Dex Petkovic for giving me remote access to his open-vz
     system and helping me reproduce this.

-- 
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com