Defining The Mtu And Mss Of The Interface; Configuring An Interface As A Point-To-Point Link - Patton electronics SmartNode Series Software Configuration Manual

10 • IP interface configuration
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 SmartWare applica-
tion software will fragment any IP packet that exceeds the MTU set for an interface. 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 (maximum 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
Mode: Interface
Step
1 node (ctx-ip)[router]#interface name Selects interface name for ICMP message processing con-
2 node (if-ip)[ name ]#mtu size
Step 3 node (if-ip)[ name ]#tcp adjust-mss {
(optional) rx|tx } { mtu | mss }
Example: Defining the MTU of the interface
The following example shows how to define the MTU of the IP interface lan to 1000 and to adjust the MSS in
both directions to MTU-40. Use the following commands in IP context configuration mode.
SN(ctx-ip)[router]#interface lan
SN(if-ip)[lan]#mtu 1000
SN(if-ip)[lan]#tcp adjust-mss rx mtu
SN(if-ip)[lan]#tcp adjust-mss tx mtu
Configuring an interface as a point-to-point link
A point-to-point network joins a single pair of routers. It is in particular used for interfaces, which have a bind-
ing to a frame relay PVC.
Mode: Configure
Step
1 node (cfg)#context ip router
2 node (ctx-ip)[router]#interface name Selects the defined interface name for configuration
3 node (if-ip)[ name ]#point-to-point
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Command
Command
SmartWare Software Configuration Guide
figuration
Sets the IP MTU packet size to size for the interface
name . A possible value for MTU packet size has to be in
the range from 48 to 1500.
Limits to the MSS (Maximum Segment Size) in TCP SYN
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.
Purpose
Selects the IP router context
Configures interface ifname as point-to-point link
Software IP interface configuration task list
Purpose