Specifications

Issue 1.0, April 2006 Section 364-180-N02

Figure 6-21 Web Tool – WAN connection: Edit Rip Versions page

In “Edit Tcp Mss Clamp” page, you can set the Tcp Mss Clamp to true or false. The TCP

Maximum Segment Size (MSS) Clamp intercepts TCP synchronization (SYN) packets as the

router forwards them. These packets advertise the MSS that the host is prepared to accept.

The clamp modifies the MSS of outgoing packets according to the MTU of the interface on

which the packet is transmitted. The MSS is modified so that it is no bigger than the interface

MTU minus the IP and TCP header. This ensures that once the connection is established, the

data packets will not be large enough to require fragmentation when sent over the link with the

smaller MTU.

Note – The TCP MSS clamp should be used with care. Allowing the router to change data in

the TCP header is against the nature of the protocol stack - the lower IP protocol alters data in

the higher level TCP protocol. A TCP stream with IPSec/VPN should never be modified by the

MSS clamp.

REMEMBER! When you have completely configured your router, please be

sure to save your new configuration by clicking the Save config link from the

left frame and follow the steps there within. Please see 0 Save config section for

more information regarding save procedures.

The availability of features and technical specifications herein subject to change without notice.