Configuring The Mtu For An Interface; Configuring The Maximum Number Of Fragments In A Packet - Cisco 4700M Configuration Manual

Configuring IP Fragment Reassembly Parameters

Configuring the MTU for an Interface

Caution

Configuring the Maximum Number of Fragments in a Packet

Cisco 4700 Series Application Control Engine Appliance Security Configuration Guide
4-44
Chapter 4
The default maximum transmission unit (MTU) is 1500 bytes in a block for
Ethernet interfaces. This value is sufficient for most applications, but you can pick
a lower number if network conditions require it. Data that is larger than the MTU
value is fragmented before being sent to the next hop router.
If you configure a Layer 7 policy map and set the maximum transmit unit (MTU)
of the ACE server-side VLAN lower than the client maximum segment size
(MSS), ensure that the maximum value of the MSS that you set for the ACE using
the set tcp mss max command is at least 40 bytes (size of the TCP header plus
options) less than the MTU of the ACE server-side VLAN. Otherwise, the ACE
may discard incoming packets from the server.
To specify the MTU for an interface, use the mtu command in interface
configuration mode. This command allows you to set the data size that is sent on
a connection. The syntax of this command is as follows:
mtu bytes
The bytes argument is the number of bytes in the MTU. Enter a number from 68
to 9216 bytes. The default is 1500 bytes.
To specify the MTU data size of 1000 bytes for an interface, enter:
host1/admin(config-if)# mtu 1000
To reset the MTU block size to 1500 bytes, use the no mtu command. For
example, enter:
host1/admin(config-if)# no mtu
You can configure the maximum number of fragments belonging to the same
packet that the ACE accepts for reassembly by using the fragment chain
command in interface configuration mode. The syntax of this command is as
follows:
fragment chain number
Configuring TCP/IP Normalization and IP Reassembly Parameters
OL-16202-01