Cisco Cisco IOS Software Release 12.4(2)XB6 Références techniques

To set the first fragment size in order to avoid further fragmentation of the second fragment in the 
network, use the ip fragment first minimum size global configuration command. Use the no form of 
the command to disable this feature.

ip fragment first minimum size size

no ip fragment first minimum size size

There are no default values.

Global configuration.

The size includes only the payload and does not include any header. The payload size must be in 
multiples of 8 bytes. Otherwise, the command is rejected with the following error.

Error Message Error Message %% First fragment payload size is not in multiples of 8 
bytes

The command configuration only indicates the minimum value for the payload of the first fragment. 

If the existing fragmentation mechanism in CEF selects the first fragment larger than the configured 
value, then the configuration is not enforced. Otherwise, CEF generates more fragments than expected.

If the configured first fragment size is more than the MTU of the output interface, the configured value 
is not enforced.

The following packet capture shows how the packet would be for IP and IP-IP tunnel packet when ip 
fragment first minimum size 80 is configured:

10:27:59.660 IST Mon Apr 13 2009                 Relative Time: 2.990258

Packet 8 of 26                                   In: FastEthernet0/1

Sets the first fragment size to avoid further fragmentation of the second 
fragment in the network. The range is 8-560 bytes. The size includes only 
the payload and does not include any header. The payload size must be in 
multiples of 8 bytes.

12.4(15)YD1

This command was introduced.