Sun Microsystems 1.0 - Manual (Page 56)

30 SunFDDI/P 1.0 Adapter User’s Guide—May 1997
4
MTU Path Discovery
Machines running a Solaris 2.x environment support MTU path discovery,
which allows the optimum MTU to be negotiated. Under most circumstances,
this ensures efficient use of the network resources. However, to enable MTU
path discovery to work, the “
don’t fragment ” bit in the packet is set, which
causes a problem with some bridges and routers that do not support this
feature. In this case, packets are not transmitted across the bridge, and the
generated error messages as a result can be misleading.
Refer to “To Disable MTU Path Discovery” for instructions on how to
accommodate bridges and routers that do not support this feature.
▼ To Tune the Maximum Transfer Unit (MTU)
The maximum transfer unit (MTU) has been optimized for pure FDDI
networks for FDDI/P. Follow these steps to change the value of the MTU on a
station running SunFDDI/P:
1. Log in as root or become superuser.
2. Edit the /etc/system file to add the following line:
The variable <packet_size> is set to the desired value for MTU entered in
octets. The default value for MTU is 4352 octets. It must be in the range 512
to 4500 octets.
3. Reboot the machine to apply the changes to the system.
Note – Additionally, the ifconfig(1M) command can be used to change the
MTU.
set pf:pf_mtu= <packet_size>