Siemens S323, S223 Ospf Maximum Transmission Unit MTU, Ospf Priority, 340 A50010-Y3-C150-2-7619

UMN:CLI	User Manual
	SURPASS hiD 6615 S223/S323 R1.5

10.2.4.6OSPF Maximum Transmission Unit (MTU)

Router verifies MTU when DD (Database Description) is exchanging among the routers on OSPF networks. Basically, OSPF network can not be organized if there are different sizes of MTUs between routers. Therefore MTU value must be consistent. Generally MTU value is 1500 bytes on Ethernet interface.

To configure MTU on OSPF interface, use the following command.

Command	Mode	Description
ip ospf mtu <576-65535>	Interface	Configures an MTU on OSPF interface.
no ip ospf mtu		Deletes a configured MTU on OSPF interface.

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Configuration as above makes MTU consistently on same OSPF network; actual MTU value on interface itself will not be changed.

On the other hands, if there are two routers which have different MTU, it can be partici- pated with OSPF network through the configuration that skips the verification of MTU value when there is DD exchanging.

To configure the switch to skip the MTU verification in DD process, use the following command.

Command	Mode	Description
ip ospf mtu-ignore	Interface	Configures the switch to skip the MTU verification in
ip ospf A.B.C.D mtu-ignore		DD process.

To configure the switch not to skip the MTU verification in DD process, use the following command.

Command	Mode	Description
no ip ospf mtu-ignore	Interface	Configures the switch not to skip the MTU verification
		in DD process.
no ip ospf A.B.C.D mtu-ignore

10.2.4.7OSPF Priority

Routers have each role to exchange the information on OSPF network. DR (Designated Router) is one of essential role to get and transmit the route information in the same area.

The router having the highest priority becomes DR (Designated Router). If there are routers which have same priority, the highest router ID will be DR.

Normally, router has priority 1, but it can be changed to make DR through the configura- tion of priority.

To configure a priority of OSPF router, use the following command.

Command	Mode	Description
ip ospf priority <0-255>	Interface	Configures a priority of OSPF router.
ip ospf A.B.C.D priority <0-255>

340 A50010-Y3-C150-2-7619