Explains the principles of TCP MSS, describing its impact on TCP packet sizing and outlining considerations for optimizing data transmission efficiency.
A TCP maximum segment size (MSS) is a parameter that
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specifies the largest amount of data, in bytes, that a communications device can receive in a single TCP segment without counting the TCP header or the IP header, and
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is specified as TCP MSS, initially in the TCP SYN packet during the TCP handshake.
TCP MSS for SYN packets
Small MSS values reduce or eliminate IP fragmentation, which results in higher overhead. You can configure the MSS of TCP SYN packets passing through a device. By default, the device dynamically adjusts the MSS based on the interface or tunnel maximum transmission unit (MTU) to ensure that TCP SYN packets are never fragmented. For data sent over an interface, the device calculates the MSS by adding the interface MTU, the IP header length, and the maximum TCP header length.