Configuring BGP route summarization
Route summarization can reduce the number of redistributed routes and the routing table size. IPv4 BGP supports automatic route summarization and manual route summarization. Manual summarization takes precedence over automatic summarization. IPv6 BGP supports only manual route summarization.
The output interface of a BGP summary route is Null 0 on the originating router. Therefore, a summary route must not be an optimal route on the originating router. Otherwise, BGP will fail to forward packets matching the route. If a summarized specific route has the same mask as the summary route, but has a lower priority, the summary route becomes the optimal route. To ensure correct packet forwarding, change the priority of the summary or specific route to make the specific route the optimal route.
Configuring automatic route summarization
Automatic route summarization enables BGP to summarize IGP subnet routes redistributed by the import-route command so BGP advertises only natural network routes.
To configure automatic route summarization (IPv4 unicast/multicast address family):
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter BGP IPv4 unicast address family view, BGP-VPN IPv4 unicast address family view, or BGP IPv4 multicast address family view. |
| N/A |
3. Configure automatic route summarization. | summary automatic | By default, automatic route summarization is not configured. |
Configuring manual route summarization
By configuring manual route summarization, you can do the following:
Summarize both redistributed routes and routes injected using the network command.
Determine the mask length for a summary route.
To configure BGP manual route summarization (IPv4 unicast/multicast address family):
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter BGP IPv4 unicast address family view, BGP-VPN IPv4 unicast address family view, or BGP IPv4 multicast address family view. |
| N/A |
3. Create a summary route in the BGP routing table. | aggregate ipv4-address { mask-length | mask } [ as-set | attribute-policy route-policy-name | detail-suppressed | origin-policy route-policy-name | suppress-policy route-policy-name ] * | By default, no summary routes are configured. |
To configure BGP manual route summarization (IPv6 unicast/multicast address family):
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter BGP IPv6 unicast address family view, BGP-VPN IPv6 unicast address family view, or BGP IPv6 multicast address family view. |
| N/A |
3. Create a summary route in the IPv6 BGP routing table. | aggregate ipv6-address prefix-length [ as-set | attribute-policy route-policy-name | detail-suppressed | origin-policy route-policy-name | suppress-policy route-policy-name ] * | By default, no summary routes are configured. |