Huawei Quidway NetEngine80E Configuration Manual page 567

HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
Context
If IS-IS is configured on a Level-1-2 device to advertise a default route, all traffic in IS-IS routing
domains will be forwarded by this Level-1-2 device. This will burden this Level-1-2 device
because no external route can be learned on the devices in the IS-IS routing domains.
If multiple Level-1-2 devices are deployed, optimal routes to other routing domains need to be
selected. To ensure optimal routes are selected, all the other devices in the IS-IS routing domains
must learn all or some external routes.
Routing policies can be configured to import or advertise external routes that meet specified
conditions to the IS-IS routing domains.
Procedure
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Configure IS-IS to import external routes.
1. Run:
system-view
The system view is displayed.
2. Run:
isis [ process-id ]
The IS-IS view is displayed.
3. Configuring IS-IS to Import External Routes
– If you want to set the cost for the imported route, you can run the import-route
{ direct | static | unr | { ospf | rip | isis } [ process-id ] | bgp [ permit-ibgp ] }
[ cost-type { external | internal } | cost cost | tag tag | route-policy route-policy-
name | [ level-1 | level-2 | level-1-2 ] ]
– If you want to keep the original cost for the imported route, you can run the import-
route { { ospf | rip | isis } [ process-id ] | bgp [ permit-ibgp ] | direct } inherit-
cost [ tag tag | route-policy route-policy-name | [ level-1 | level-2 | level-1-2 ] ]
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command to import the external routes. When configuring IS-IS to retain the
original cost value of the imported route, the source routes cannot be static.
NOTE
IS-IS will advertise all imported external routes to an IS-IS routing domain by default.
If only some imported external routes need to be advertised, run the filter-policy export
command to set a filtering policy.
If an IS-IS device has a small routing table capacity, run the import-route limit limit-
number [ threshold-alarm upper-limit upper-limit-value lower-limit lower-limit-value ]
{ level-1 | level-2 | level-1-2 } command to set the maximum number of external routes that
can be imported into an IS-IS routing domain.
Configure IS-IS to advertise some external routes to an IS-IS routing domain.
1. Run:
system-view
The system view is displayed.
2. Run:
isis [ process-id ]
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7 IS-IS Configuration
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command to import the external routes.
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