TCP MSS

Hi,

Data is encapsulated at the transport layer and then sent to the network layer. Upon receiving the IP data, the network layer determines the interface to which it sends data and obtains the MTU of the interface. If the data packet length is greater than the MTU, the network layer fragments the data packet, encapsulates the fragments into an IP data packet, and then sends the IP data packet to the link layer. If fragmentation is not performed, packet loss occurs because the length of the data packet is greater than the MTU of the link layer.

If the path MTU is unavailable on one end of a TCP connection, this end cannot adjust the TCP packet size based on the MTU. As a result, this end may send TCP packets that are longer than the MTUs on intermediate devices, which will discard these packets. To prevent this problem, decrease the TCP-MSS value on either end of a TCP connection or on the intermediate device. Then the MSS value negotiated by both ends will not exceed this maximum MSS value, and accordingly TCP packets sent from both ends will not be longer than this maximum MSS value and can travel through the intermediate network.

Hope it helps!