The MSS value in the TCP protocol is used to specify the length of a TCP packet that can be transmitted without being fragmented. During the TCP connection establishment, the MSS value is carried in a SYN packet to notify the peer end of the maximum size of a packet that can be received by the local end.
After the MSS value is set in the MAP instance view, a device changes the MSS value in all TCP packets that belong to the MAP service. If the MSS value in the negotiation process is greater than the configured MSS value, the device uses the MSS value configured by the user. If the MSS value during the negotiation is smaller than the configured MSS value, the MSS value in the negotiation process is retained. When the maximum packet length is set, the maximum length of IP packets that can be sent by the interface is calculated using a formula (Maximum packet length + 20-byte IP header + 20-byte TCP header). The maximum length of IP packets that can be sent by the interface is limited by the MTU value. Therefore, when the value calculated using the formula (Maximum packet length + 20-byte IP header + 20-byte TCP header) is greater than the MTU value, the packets are fragmented. Therefore, you are advised to set the TCP MSS value as large as possible without causing packet fragmentation to improve packet transmission efficiency. If the size of packets for MAP processing is larger than a link MTU, the packets are fragmented. You can reduce the MSS value in TCP, which prevents a service board from fragmenting packets and helps improve MAP efficiency.
The system view is displayed.
The MAP-T instance view is displayed.
An MSS value is set in TCP SYN and SYN ACK packets.
The configuration is committed.