Cisco 4700M Configuration Manual page 269

Chapter 4 Configuring TCP/IP Normalization and IP Reassembly Parameters
Configuring a Connection Parameter Map for TCP/IP Normalization and Termination
Both the host and the server can set the MSS when they first establish a
connection. If either maximum exceeds the value that you set with the set tcp mss
max command, then the ACE overrides the maximum value and inserts the value
that you set. If either maximum is less than the value that you set with the set tcp
mss min command, then the ACE overrides the maximum and inserts the
minimum value that you set (the minimum value is actually the smallest
maximum allowed). For example, if you set a maximum size of 1200 bytes and a
minimum size of 400 bytes, when a host requests a maximum size of 1300 bytes,
then the ACE alters the packet to request 1200 bytes (the maximum). If another
host requests a maximum value of 300 bytes, then the ACE alters the packet to
request 400 bytes (the minimum).
If the host or server does not request an MSS, the ACE assumes that the RFC 793
default value of 536 bytes is in effect.
For example, to set the minimum acceptable MSS size to 768 bytes, and the
maximum acceptable MSS size to 1500, enter:
host1/C1(config-parammap-conn)# set tcp mss min 768 max 1500
To reset the minimum MSS to the default value of 0 bytes and the maximum MSS
to the default value of 1460, enter:.
host1/C1(config-parammap-conn)# no set tcp mss
Cisco 4700 Series Application Control Engine Appliance Security Configuration Guide
4-11
OL-16202-01