Hi James, If you have PATH MTU DISCOVERY turned on then you won't have to worry about fragmentation. For zOS TCP Parms this is: IPCONFIG PATHMTUDISCOVERY
On SLES8 this is already on by default: lnxsod1:/proc/sys/net/ipv4 # cat ip_no_pmtu_disc 0 lnxsod1:/proc/sys/net/ipv4 # (note this is negated because it is "no") If you really want to change the MTU under SLES8 for eth0 you can manually one time do: ifconfig eth0 mtu 1492 Or change the boot script: lnxsod1:/etc/sysconfig/network # grep -i mtu ifcfg-eth0 MTU="1500" lnxsod1:/etc/sysconfig/network # All the Best Mark Perry > -----Original Message----- > From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of > James Melin > Sent: 04 January 2005 15:20 > To: [email protected] > Subject: Changing MTU size on an ethernet interface > > I'm in an interesting situation..... Our network, hence my linux guests, > use an MTU size of 1500. As it turns out, our z/os systems use an MTU > size > of 1492. We just started using a z/os HTTP server outside the firewall to > do reverse proxy inside to our linux guests. When I do not go through the > z/OS httpd server, things go swimmingly. I suspect I'm getting retransmit > delays with an 8 byte difference in MTU. I'm not sure under SLES8 where to > change the MTU size for ETH0 to see if making those match will change the > behaviour we are seeing. > > Anyone know where to tweak this particular thing after the fact? > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or > visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
