Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 672)

644 Multi-Service IronWare Routing Configuration Guide
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Configuring OSPFv3
Syntax: [no] area number | ipv4-address virtual-link router-id [dead-interval seconds |
hello-interval seconds | retransmit-interval seconds | transmit-delay seconds]
The area number | ipv4-address parameter specifies the transit area ID.
The router-id parameter specifies the router ID of the OSPF router at the remote end of the virtual
link. To display the router ID on a device, enter the show ip command.
The dead-interval, hello-interval, retransmit-interval, and transmit-delay parameters are described
earlier in this section.
Changing the reference bandwidth for the cost
on OSPFv3 interfaces
Each interface on which OSPFv3 is enabled has a cost associated with it. The device advertises its
interfaces and their costs to OSPFv3 neighbors. For example, if an interface has an OSPF cost of
10, the device advertises the interface with a cost of 10 to other OSPF routers.
By default, OSPF cost of an interface is based on the port speed of the interface. The software uses
the following formula to calculate the cost.
Cost = reference-bandwidth/interface-speed
By default, the reference bandwidth is 100 Mbps. If the resulting cost is less than 1, the software
rounds the cost up to 1. The default reference bandwidth results in the following costs:
• 10 Mbps port cost = 100/10 = 10
• 100 Mbps port cost = 100/100 = 1
• 1000 Mbps port cost = 100/1000 = 0.10, which is rounded up to 1
• 155 Mbps port cost = 100/155 = 0.65, which is rounded up to 1
• 622 Mbps port cost = 100/622 = 0.16, which is rounded up to 1
• 2488 Mbps port cost = 100/2488 = 0.04, which is rounded up to 1
The interfaces that consist of more than one physical port is calculated as follows:
• LAG group – The combined bandwidth of all the ports.
• Virtual (Ethernet) interface – The combined bandwidth of all the ports in the port-based VLAN
that contains the virtual interface.
You can change the default reference bandwidth from 100 Mbps to a value from 1 through
4294967 Mbps.
If a change to the reference bandwidth results in a cost change to an interface, the device sends a
link-state update to update the costs of interfaces advertised by the device.
NOTE
If you specify a cost for an interface, your specified cost overrides the cost that the software
calculates.
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 1.
• The cost of a virtual link is calculated using the Shortest Path First (SPF) algorithm and is not
affected by the auto-cost feature.