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Foundry Configuration Guide for the FESX, FSX, and FWSX
20 - 22
© Foundry Networks, Inc.
December 2005
If a change to the reference bandwidth results in a cost change to an interface, the Layer 3 Switch sends a link-
state update to update the costs of interfaces advertised by the Layer 3 Switch.
NOTE:
If you specify the cost for an individual interface, the cost you specify overrides the cost calculated by the
software.
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:
FESX424 Router(config-ospf-router)# auto-cost reference-bandwidth 500
The reference bandwidth specified in this example results in the following costs:
•
10 Mbps port’s cost = 500/10 = 50
•
100 Mbps port’s cost = 500/100 = 5
•
1000 Mbps port’s cost = 500/1000 = 0.5, which is rounded up to 1
•
155 Mbps port’s cost = 500/155 = 3.23, which is rounded up to 4
•
622 Mbps port’s cost = 500/622 = 0.80, which is rounded up to 1
•
2488 Mbps port’s 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 – 4294967. The default is
100, which results in the same costs as previous software releases.
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:
FESX424 Router(config-ospf-router)# no auto-cost reference-bandwidth
Define Redistribution Filters
Route redistribution imports and translates different protocol routes into a specified protocol type. On Foundry
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).
In Figure 20.7 on page 20-23, an administrator wants to configure the FastIron Layer 3 Switch acting as the ASBR
(Autonomous System Boundary Router) between the RIP domain and the OSPF domain to redistribute routes
between the two domains.
Summary of Contents for FastIron Edge Switch X424
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