Ospf Maximum Transmission Unit (Mtu); Ospf Priority - Siemens S223 User Manual

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10.2.4.6
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10.2.4.7
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OSPF 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
ip ospf mtu <576-65535>
no ip ospf mtu
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
ip ospf mtu-ignore
ip ospf A.B.C.D mtu-ignore
To configure the switch not to skip the MTU verification in DD process, use the following
command.
Command
no ip ospf mtu-ignore
no ip ospf A.B.C.D mtu-ignore

OSPF 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
ip ospf priority <0-255>
ip ospf A.B.C.D priority <0-255>
SURPASS hiD 6615 S223/S323 R1.5
Mode
Configures an MTU on OSPF interface.
Interface
Deletes a configured MTU on OSPF interface.
Mode
Configures the switch to skip the MTU verification in
Interface
DD process.
Mode
Configures the switch not to skip the MTU verification
Interface
in DD process.
Mode
Interface Configures a priority of OSPF router.
User Manual
Description
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A50010-Y3-C150-2-7619