tcp-mss (Protocols BGP)
Syntax
tcp-mss segment-size;
Hierarchy Level
[edit logical-systems logical-system-name protocols bgp], [edit logical-systems logical-system-name protocols bgp group group-name], [edit logical-systems logical-system-name protocols bgp group group-name neighbor neighbor-name], [edit logical-systems logical-system-name routing-instances routing-instance-name protocols bgp], [edit logical-systems logical-system-name routing-instances routing-instance-name protocols bgp group group-name], [edit logical-systems logical-system-name routing-instances routing-instance-name protocols bgp group group-name neighbor neighbor-name], [edit protocols bgp], [edit protocols bgp group group-name], [edit protocols bgp group group-name neighbor neighbor-name], [edit routing-instances routing-instance-name protocols bgp], [edit routing-instances routing-instance-name protocols bgp group group-name], [edit routing-instances routing-instance-name protocols bgp group group-name neighbor neighbor-name]
Description
Configure the maximum segment size (MSS) for the TCP connection for BGP neighbors.
You can set the MSS globally or for a particular neighbor. If the router receives a
TCP packet with the SYN bit and the MSS option set, and the MSS option specified in
the packet is larger than the MSS value specified by the tcp-mss
statement, the router replaces the MSS value in the packet with the lower value
specified by the tcp-mss statement.
The MSS is only valid in increments of 2 KB. The value used is based on the value set, but is rounded down to the nearest multiple of 2048.
This configuration statement is for host-originated packets. To configure the TCP MSS value for transit traffic on a particular interface, see tcp-mss (Interfaces) .
There
are multiple factors that define the MSS value for TCP packets, which are reflected
in the MSS value displayed in the output of the show system connections command:
-
The MSS value offered by the peer in the SYN packet.
-
Rounding the MSS off to the nearest multiple of 2048.
-
The MTU value of the interface.
-
The configured path MTU value.
-
Whether TCP sessions are not directly connected and path MTU discovery is disabled.
-
Whether the TCP sessions are on a directly-connected network.
Options
| segment-size | MSS for the TCP connection.
|
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.
Release Information
Statement introduced in Junos OS Release 8.1.