Patton electronic SmartNode 4110 Series manual Defining the MTU and MSS of the interface

SmartWare Software Configuration Guide10 • IP interface configuration

Mode: Interface

Step	Command	Purpose
1	node(ctx-ip)[router]#interface name	Selects the interface name for ICMP message pro-
		cessing configuration
2	node(if-ip)[name]# icmp router-discovery	Enables to send router advertisement broadcast
		messages

Example: Router advertisement broadcast message

The following example shows how to enable sending router advertisement broadcast messages on IP interface lan. Use the following commands in IP context configuration mode.

node(ctx-ip)[router]#interface lan node(if-ip)[lan]#icmp router-discovery

Defining the MTU and MSS of the interface

All interfaces have a default MTU packet size. You can adjust the IP MTU size so that the IP packet that exceeds the MTU set for an interface is exceeded. The default MTU packet size is set to 1500 for an interface. In cases where fragmentation is not allowed along the IP connection, forcing a reduction of the MSS (maxi- mum segment size) is the only viable solution.

Note All devices on a physical medium must have the same protocol MTU in order to operate accurately.

Procedure: To set the MTU packet size or the MSS to size on the interface name

Mode: Interface

Step	Command	Purpose
1	node(ctx-ip)[router]#interface name	Selects the interface name for ICMP message processing
		configuration
2	node(if-ip)[name]#mtu size	Sets the IP MTU packet size to size of the interface name.
		The MTU packet size value must be in the range from 48
		to 1500.
3	node(if-ip)[name]#tcp adjust-mss {	Limits to the MSS (Maximum Segment Size) in TCP SYN
(optional)	rxtx } { mtu mss }	packets to mss or to MTU (Maximum Transmit Unit) - 40
		Bytes, if ‘mtu’ is used. ‘rx’ applies to packets which
		arrive inbound at this IP interface, ‘tx’ to packets which
		leave outbound of this IP interface.
		It is recommended to use ‘mtu’ inbound and outbound.

Example: Defining the MTU of the interface

IP interface configuration task list 125