Amer Networks E5Web GUI - Manual (Page 724)

12.2. TCP Level Settings
TCP Option Sizes
Verifies the size of TCP options. This function acts in the same way as IPOptionSizes described
above.
Default: ValidateLogBad
TCP MSS Min
Determines the minimum permissible size of the TCP MSS. Packets containing maximum
segment sizes below this limit are handled according to the next setting.
Default: 100 bytes
TCP MSS on Low
Determines the action taken on packets whose TCP MSS option falls below the stipulated
TCPMSSMin value. Values that are too low could cause problems in poorly written TCP stacks.
Default: DropLog
TCP MSS Max
Determines the maximum permissible TCP MSS size. Packets containing maximum segment sizes
exceeding this limit are handled according to the next setting.
Default: 1460 bytes
TCP MSS VPN Max
As is the case with TCPMSSMax, this is the highest Maximum Segment Size allowed. However,
this setting only controls MSS in VPN connections. This way, cOS Core can reduce the effective
segment size used by TCP in all VPN connections. This reduces TCP fragmentation in the VPN
connection even if hosts do not know how to perform MTU discovery.
This setting must be less than the maximum IPsec MTU size and the maximum IPsec MTU size
must be less than the maximum packet size handled by the physical interface.
Default: 1400 bytes
TCP MSS On High
Determines the action taken on packets whose TCP MSS option exceeds the stipulated
TCPMSSMax value. Values that are too high could cause problems in poorly written TCP stacks or
give rise to large quantities of fragmented packets, which will adversely affect performance.
Default: Adjust
TCP MSS Log Level
Determines when to log regarding too high TCP MSS, if not logged by TCPMSSOnHigh.
Chapter 12: Advanced Settings
724