Using `route .... -mtu' on local network

Mikhail Teterin mi+mxmoz at aldan.algebra.com
Tue Sep 14 10:07:15 PDT 2004


Hello!

Most of our hosts can only do the regular 1500-byte frames, but some are 
Jumbo Frames capable.

I'm trying to make these few servers talk to _each other_ using bigger 
frames (the switch supports them) without breaking the LAN into subnets.

In the past someone suggested, I try explicit -mtu switch to the 
route(8). So, with two -current machines on the same LAN (`mi' and 
`pandora') I try:

    mi# route add pandora -iface em0 -mtu 4000
    add host pandora: gateway em0
    mi# route get pandora
       route to: pandora
    destination: pandora
      interface: em0
          flags: <UP,HOST,DONE,LLINFO,STATIC>
     recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      
mtu     expire
           0         0         0         0         0         0      
4000         0

Even ping-ing pandora stops working.... I have to `route delete pandora' 
for things to recover. Any suggestions? Thanks!

    -mi


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