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PowerConnect B-Series FCX Configuration Guide 947
53-1002266-01
Configuring OSPF
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Interface types to which the reference bandwidth does not apply
Some interface types are not affected by the reference bandwidth and always have the same cost
regardless of the reference bandwidth in use:
• The cost of a loopback interface is always 0.
• The cost of a virtual link is calculated using the Shortest Path First (SPF) algorithm and is not
affected by the auto-cost feature.
• The bandwidth for tunnel interfaces is 9 Kbps and is not affected by the auto-cost feature.
Changing the reference bandwidth
To change the reference bandwidth, enter a command such as the following at the OSPF
configuration level of the CLI.
PowerConnect(config-ospf-router)#auto-cost reference-bandwidth 500
The reference bandwidth specified in this example results in the following costs:
• 10 Mbps port cost = 500/10 = 50
• 100 Mbps port cost = 500/100 = 5
• 1000 Mbps port cost = 500/1000 = 0.5, which is rounded up to 1
• 155 Mbps port cost = 500/155 = 3.23, which is rounded up to 4
• 622 Mbps port cost = 500/622 = 0.80, which is rounded up to 1
• 2488 Mbps port cost = 500/2488 = 0.20, which is rounded up to 1
The costs for 10 Mbps, 100 Mbps, and 155 Mbps ports change as a result of the changed
reference bandwidth. Costs for higher-speed interfaces remain the same.
Syntax: [no] auto-cost reference-bandwidth <num>
The <num> parameter specifies the reference bandwidth and can be a value from 1 through
4294967. The default is 100. For 10 Gbps OSPF interfaces, in order to differentiate the costs
between 100 Mbps, 1000 Mbps, and 10,000 Mbps interfaces, set the auto-cost reference
bandwidth to 10000, whereby each slower link is given a higher cost
To restore the reference bandwidth to its default value and thus restore the default costs of
interfaces to their default values, enter the following command.
PowerConnect(config-ospf-router)#no auto-cost reference-bandwidth
Defining redistribution filters
Route redistribution imports and translates different protocol routes into a specified protocol type.
On Dell routers, redistribution is supported for static routes, OSPF, RIP, and BGP4. When you
configure redistribution for RIP, you can specify that static, OSPF, or BGP4 routes are imported into
RIP routes. Likewise, OSPF redistribution supports the import of static, RIP, and BGP4 routes into
OSPF routes. BGP4 supports redistribution of static, RIP, and OSPF routes into BGP4.
NOTE
The Layer 3 Switch advertises the default route into OSPF even if redistribution is not enabled, and
even if the default route is learned through an IBGP neighbor. IBGP routes (including the default
route) are not redistributed into OSPF by OSPF redistribution (for example, by the OSPF redistribute
command).