Cisco Cisco IOS Software Release 12.2(14)S

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The TCP MSS Adjustment feature enables the configuration of the maximum segment size (MSS) for 
transient packets that traverse a router, specifically TCP segments in the SYN bit set, when Point to Point 
Protocol over Ethernet (PPPoE) is being used in the network. PPPoE truncates the Ethernet maximum 
transmission unit (MTU) 1492, and if the effective MTU on the hosts (PCs) is not changed, the router in 
between the host and the server can terminate the TCP sessions. The ip tcp adjust-mss command 
specifies the MSS value on the intermediate router of the SYN packets to avoid truncation.

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12.2(4)T

This feature was introduced.

12.2(8)T

The command that was introduced by this feature was changed from ip 
adjust-mss to ip tcp adjust-mss.

12.2(27)SBA

This feature was integrated into Cisco IOS Release 12.2(27)SBA.