Adjusting performance by changing the VLAN or subnet interface settings
Optional: For more information, see Adjusting performance by changing the VLAN or subnet interface settings.
Indicating the cost per-interface
Syntax:
ip ospf [ ip-address | all ] cost 1-65535
Used in the VLAN context to indicate the overhead required to send a packet across an interface. You can modify the cost to differentiate between 100 Mbps and 1000 Mbps (1 Gbps) links.
Allows different costs for different subnets in the VLAN.
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ip ospf cost 1-65535
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Assigns the specified cost to all networks configured on the VLAN.
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ip ospf ip-address cost 1-65535
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Assigns the specified cost to the specified subnet on the VLAN.
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ip ospf all cost 1-65535
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Assigns the specified cost to all networks configured on the VLAN. (Operates the same as the ip ospf cost option, above.)
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Default: 1; range 1–65535
Indicating the per-interface dead interval
Syntax:
ip ospf [ ip-address | all ] dead-interval 1-65535
Used in the VLAN context to indicate the number of seconds that a neighbor router waits for a hello packet from the specified interface before declaring the interface "down." Allows different settings for different subnet interfaces in the VLAN.
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ip ospf dead-interval 1-65535
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Assigns the specified dead interval to all networks configured on the VLAN.
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ip ospf ip-address dead-interval 1-65535
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Assigns the specified dead interval to the specified subnet on the VLAN.
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ip ospf all dead-interval 1-65535
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Assigns the specified dead interval to all networks configured on the VLAN. (Operates the same as the ip ospf dead-interval option, above.)
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Default: 40 seconds; range 1–65535 seconds
Indicating the per-interface hello interval
Syntax:
ip ospf [ ip-address | all ] hello-interval 1-65535
Used in the VLAN context to indicate the length of time between the transmission of hello packets from the routing switch to adjacent neighbors.
The value can be from 1 to 65535 seconds. Allows different settings for different subnet interfaces in the VLAN.
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ip ospf hello-interval 1-65535
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Assigns the specified hello interval to all networks configured on the VLAN.
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ip ospf ip-address hello-interval 1-65535
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Assigns the specified hello interval to the specified subnet on the VLAN.
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ip ospf all hello-interval 1-65535
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Assigns the specified hello interval to all networks configured on the VLAN. Operates the same as the ip ospf hello-interval option.
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Default: 10 seconds; range 1–65535 seconds
Changing priority per-interface
Syntax:
ip ospf [ ip-address | all ] priority 1- 255
The priority is used when selecting the DR and backup DRs (BDRs.)
The value can be from 0 to 255 (with 255 as the highest priority.) If you set the priority to 0, the routing switch does not participate in DR and BDR election. Allows different settings for different subnet interfaces in the VLAN.
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ip ospf priority 1-255
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Assigns the specified priority to all networks configured on the VLAN.
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ip ospf ip-address priority 1-255
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Assigns the specified priority to the specified subnet on the VLAN.
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ip ospf all priority 1-255
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Assigns the specified priority to all networks configured on the VLAN. Operates the same as the ip ospf priority option.
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Default: 1; range 0–255
Changing retransmit interval per-interface
Syntax:
ip ospf [ ip-address | all ] retransmit-interval 0-3600
Used in the VLAN context to enable changing the retransmission interval for LSAs on an interface. Allows different settings for different subnet interfaces in the VLAN.
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ip ospf priority 1-255
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Assigns the specified retransmit interval to all networks configured on the VLAN.
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ip ospf ip-address priority 1-255
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Assigns the specified retransmit interval to the specified subnet on the VLAN.
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ip ospf all priority 1-255
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Assigns the specified retransmit interval to all networks configured on the VLAN. Operates the same as the ip ospf priority option.
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Default: 5 seconds; range: 1–3600 seconds
Changing transit-delay per-interface
Syntax:
ip ospf [ ip-address | all ] transit-delay 0-3600
Used in the VLAN context to enable changing the time it takes to transmit link-state update packets on this interface. Allows different settings for different subnet interfaces in the VLAN.
Default: 1 second; range: 1–3600 seconds
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ip ospf transit-delay 1-3600
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Reconfigures the estimated number of seconds it takes to transmit a link-state update packet to all networks configured on the VLAN.
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ip ospf ip-address transit-delay 1-3600
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Reconfigures the estimated number of seconds it takes to transmit a link-state update packet to all networks configured on the specified subnet on the VLAN.
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ip ospf all transit-delay 1-3600
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Reconfigures the estimated number of seconds it takes to transmit a link-state update packet to all networks configured on the VLAN. (Operates the same as the ip ospf transit-delay option, above.)
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Examples of changing per-interface settings
Suppose that VLAN 30 is multinetted, with two subnets in area 1 and one subnet in area 5:
vlan 30
ip ospf 10.10.30.1 area 0.0.0.1
ip ospf 10.10.31.1 area 0.0.0.1
ip ospf 10.10.32.1 area 0.0.0.5
If you wanted to quickly reconfigure per-interface OSPF settings for VLAN 30, such as those listed below, you could use the commands shown in Figure Reconfiguring per-interface settings in a multinetted VLAN.
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Assign a cost of "5" to the two subnets in area 1 and a cost of "10" to the subnet in area 5.
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Assign a dead interval of 45 seconds to the subnets in area 1 and retain the default setting (40 seconds) for the subnet in area 5.
