Summarizing Local MBGP Routes

Configuring route summarization can reduce the size of a routing table on a peer.

Context

On a large-scale MBGP network, configuring route summarization can reduce the number of advertised route prefixes and improve MBGP stability.

MBGP supports automatic and manual route summarization.

Procedure

Configure automatic route summarization.
1. Run system-view
  The system view is displayed.
2. Run bgp as-number
  The BGP view is displayed.
3. Run ipv4-family multicast
  The BGP-IPv4 multicast address family view is displayed.
4. Run summary automatic
  Subnet routes are summarized based on natural network segment masks.
  
  This command summarizes the routes imported into the MBGP routing table. The routes may be direct routes, static routes, RIP routes, OSPF routes, or IS-IS routes. Note that this command is invalid for the routes imported by using the network command.
5. Run commit
  The configuration is committed.
Configure manual route summarization.
1. Run system-view
  The system view is displayed.
2. Run bgp as-number
  The BGP view is displayed.
3. Run ipv4-family multicast
  The BGP-IPv4 multicast address family view is displayed.
4. Run one of the following commands to configure route summarization as needed.
  - To advertise all summarized routes and specific routes, run:
```
aggregate ipv4-address { mask | mask-length }
```
  - To advertise only summarized routes, run:
```
aggregate ipv4-address { mask | mask-length } detail-suppressed
```
  - To advertise specific routes, run:
```
aggregate ipv4-address { mask | mask-length } suppress-policy route-policy-name3
```
    Using the peer route-policy command can also advertise specific routes.
  - To generate the summarized route used for loop detection, run:
```
aggregate ipv4-address { mask | mask-length } as-set
```
  - To configure the attributes of summarized routes, run:
```
aggregate ipv4-address { mask | mask-length } attribute-policy route-policy-name1
```
    The peer route-policy command can also configure the attributes of summarized routes.
    
    If as-set is configured in the aggregate command, the AS_Path attribute configured in the apply as-path command does not take effect.
  - To generate summarized routes based on some of the specific routes, run:
```
aggregate ipv4-address { mask | mask-length } origin-policy route-policy-name2
```
  Only the routes that exist in the local MBGP routing table can be manually summarized. For example, if the route 10.1.1.0/24 is not in the MBGP routing table, MBGP will not advertise the summary route even though the aggregate 10.1.0.0 16 command is run.
5. Run commit
  The configuration is committed.