# tcp mss

#### Syntax

[ ip ] tcp mss [ vrf vrfName ] mssValue

no [ ip ] tcp mss [ vrf vrfName ]

#### Release Information

Command introduced before JunosE Release 7.1.0.
ip keyword made optional in JunosE Release 7.2.0.

#### Description

Specifies the MSS value for TCP to use. The no version removes the MSS value, and the router uses the advertised MSS derived from the MTU of the output interface.

| Note: The MSS value is equal to the MTU value minus the IP or IPv6 and TCP headers. This means that the MSS value is generally 40 bytes less than the MTU (for IPv4) and 60 bytes less than the MTU (for IPv6.

#### Options

- ip—Optional keyword for use with older scripts
- vrfName—Name of the VRF; string of 1–32 alphanumeric characters
- mssValue—Value for MSS that you want TCP to use; in the range 536–65495 bytes for IPv4 and 1280–65495 bytes for IPv6

#### Mode

Interface Configuration