AI2524 Router Card User’s Manual

Specify the MTU Size

All interfaces have a default maximum packet size. However to reduc fragmentation, you can set the MTU size of the packets sent on the in- terface. The minimum value is 512; the default and maximum packet size depends on the interface type.

Changing the MTU value with the mtu interface configuration com- mand can affect the CLNS MTU value. If the CLNS MTU is at its maximum given the interface MTU, the CLNS MTU will change with the interface MTU. However, the reverse is not true; changing th CLNS MTU value has no effect on the value for the mtu interface con- figuration command.

In interface configuration mode, set the CLNS MTU packet size for a specified interface:

clns mtu size

Warning: The CTR card does not support the switching of frames larger than 4472 bytes. Interoperability problems might occur if CTR cards are intermixed with other Token Ring cards on the same network. These problems can be mini mized by lowering the CLNS MTU sizes to be the same on all routers on the network.

Disable Checksums

When the ISO CLNS routing software originates a CLNS packet, by default it generates checksums. In interface configuration mode, dis- able checksum generation:

no clns checksum

Warning: Enabling checksum generation has no effect on routing packets (ES-IS, ISO IGRP, and IS-IS) originated by th router; it applies to pings and traceroute packets.

Disable Fast Switching Through the Cache

Fast switching through the cache is enabled by default for all sup- ported interfaces. In interface configuration mode, disable fast switch- ing:

no clns route-cache

Warning: The cache still exists and is used after the no clns route-cacheinterface configuration command is used; the software just does not do fast switching through the cache.

Page 9-54

August 1997

 

2524UM

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AIS AI2524 Router Card User’s Manual Specify the MTU Size, Disable Checksums, Disable Fast Switching Through the Cache