Watchguard V10 Command Line Interface Manual page 126

CHAPTER 3: Configuration Mode Commands
mss_adjustment
WG#config<ENTER>
WG(config)#system <ENTER>
WG(config-system)#mss_adjustment
mss_adjustment [auto| limit_to <num> | disable]
Effect
- Oversized packets can result in fragmentation,
- Proxies may require MSS adjustment to prevent
- Some older systems do not support MTU to
Arguments
112
## limit_to range - 40-1460 bytes
Sets the TCP Maximum Segment Size for the
system. This feature works in conjunction with the
MTU settings to limit the size of packets, if
configured. This feature overcomes the following
problems:
degrading VPN performance.
fragmentation.
regulate packet size. This feature works along
with MTU; it does not replace MTU.
auto
Auto adjustment calculates the MSS automatically,
using the following calculations:
Determines the lesser value of the input port MTU
and the output port MTU. Subtracts packet
overhead, including IP and TCP addressing,
VLAN, ESP, PPPoE, AH, and UDP encapsulation.
The result is then rounded down to the next lower
multiple of 8 bits (8-bit aligned) to determine the
size in bytes that is required for packet
WatchGuard Vclass 5.1