146
The default route is only advertised to routers at the same level. You can use a routing policy to generate
the default route only when a local routing entry is matched by the policy.
To advertise a default route:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis
[
process-id
] [
vpn-instance
vpn-instance-name
]
N/A
3.
Advertise a default
route.
default-route-advertise
[
route-policy
route-policy-name
| [
level-1
|
level-1-2
|
level-2
] ] *
By default, the function is disabled.
Configuring IS-IS route redistribution
Redistributing large numbers of routes on a device may affect the performance of other devices in the
network. If this happens, you can configure a limit on the number of redistributed routes in order to limit
the number of routes to be advertised.
Only active routes can be redistributed. Use the
display ip routing-table
protocol
command to display
route state information.
To configure IS-IS route redistribution from other routing protocols:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis
[
process-id
] [
vpn-instance
vpn-instance-name
]
N/A
3.
Redistribute routes
from another
routing protocol.
import-route
protocol
[
process-id
|
all-processes
|
allow-ibgp
] [
cost
cost
|
cost-type
{
external
|
internal
} |
[
level-1
|
level-1-2
|
level-2
] |
route-policy
route-policy-name
|
tag
tag
] *
By default:
•
No route is redistributed.
•
If no level is specified, routes
are redistributed into the Level-2
routing table.
4.
Configure the
maximum number
of redistributed
Level 1/Level 2
IPv4 routes.
import-route limit
number
Optional.
The default varies with devices.
Configuring IS-IS route filtering
You can reference a configured ACL, IP prefix list, or routing policy to filter routes calculated from the
received LSPs and the routes redistributed from other routing protocols.
Filtering routes calculated from received LSPs
IS-IS saves the LSPs received from neighbors in the LSDB, uses the SPF algorithm to calculate the shortest
path tree with itself as the root, and installs the routes into the IS-IS routing table.
By referencing a configured ACL, IP prefix list, or routing policy, you can filter the calculated routes. Only
the routes matching the filter can be added into the IS-IS routing table.
