344 CHAPTER 29: IS-IS CONFIGURATION
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In the case no interface cost is specified in interface view or system view and
automatic cost calculation is enabled
■ When the cost style is wide or wide-compatible, IS-IS automatically
calculates the interface cost based on the interface bandwidth, using the
formula: interface cost = bandwidth reference value/interface bandwidth, and
the maximum calculated cost is 16777214.
■ When the cost style is narrow, narrow-compatible, or compatible, if the
interface is a loopback interface, the cost value is 0; otherwise, the cost value is
automatically calculated as follows: if the interface bandwidth is in the range of
1 M to 10 M, the interface cost is 60; if the interface bandwidth is in the range
of 11 M to 100 M, the interface cost is 50; if the interface bandwidth is in the
range of 101 M to 155 M, the interface cost is 40; if the interface bandwidth is
in the range of 156 M to 622 M, the interface cost is 30; if the interface
bandwidth is in the range of 623 M to 2500 M, the interface cost is 20, and
the default interface cost of 10 is used for any other bandwidths.
Configuring the
Maximum Number of
Equal Cost Routes
If there are more than one equal cost routes to the same destination, the traffic
can be load balanced to enhance efficiency.
Follow these steps to configure the maximum number of equal cost routes:
Configuring IS-IS Route
Summarization
This task is to configure a summary route, so routes falling into the network range
of the summary route are summarized with one route for advertisement. Doing so
can reduce the size of routing tables, as well as the LSP and LSDB generated by the
router itself. Both IS-IS and redistributed routes can be summarized.
Follow these steps to configure route summarization:
Specify an IS-IS cost style cost-style { narrow | wide |
wide-compatible |
{ compatible |
narrow-compatible }
[ relax-spf-limit ]}
Optional
narrow by default
Configure a bandwidth
reference value for automatic
IS-IS cost calculation
bandwidth-reference value Optional
100 Mbps by default
Enable automatic IS-IS cost
calculation
auto-cost enable Required
Disabled by default.
To do… Use the command… Remarks
To do… Use the command… Remarks
Enter system view system-view --
Enter IS-IS view isis [ process-id ] --
Specify the maximum number
of equal cost routes for load
balancing
maximum load-balancing
number
Optional
The default number is 4.
To do… Use the command… Remarks
Enter system view system-view -
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