Using XPL to Filter the BGP Routes to Be Advertised

A BGP device can use a route-filter to filter the routes to be advertised and modify route attributes to control the network traffic forwarding path.

Usage Scenario

BGP is used to transmit routing information between ASs, and route advertisement directly affects traffic forwarding.

In most cases, a BGP routing table has a large number of routes. Transmitting them will intensify the load of a device. To address this problem, configure the device to advertise only desired routes.

In addition, multiple routes to the same destination may exist and travel through different ASs. To direct routes to specific ASs, you also need to filter the routes to be advertised.

You can use XPL route-filters to control the BGP routes to be advertised to all peers or peer groups or to a specified peer or peer group.

Pre-configuration Tasks

Before using XPL to filter the BGP routes to be advertised, configure basic BGP functions.

Procedure

Use XPL to filter the BGP routes to be advertised to all peers or peer groups.
Perform the following steps on the BGP device:
1. Run system-view
  The system view is displayed.
2. Run bgp { as-number-plain | as-number-dot }
  The BGP view is displayed.
3. Run ipv4-family unicast
  The IPv4 unicast address family view is displayed.
4. Run route-filter route-filter-name export [ direct | isis process-id | ospf process-id | rip process-id | static ]
  The BGP device is configured to filter the routes to be advertised to all peers or peer groups.
5. Run commit
  The configuration is committed.
Use XPL to filter the BGP routes to be advertised to a specific peer or peer group.
Perform the following steps on the BGP device:
1. Run system-view
  The system view is displayed.
2. Run bgp { as-number-plain | as-number-dot }
  The BGP view is displayed.
3. Run ipv4-family unicast
  The IPv4 unicast address family view is displayed.
4. Run peer { group-name | ipv4-address } route-filter route-filter-name export
  The BGP device is configured to filter the routes to be advertised to the specified peer or peer group.
5. Run commit
  The configuration is committed.

Checking the Configuration

Run the following commands to check configurations:

Run the display xpl route-filter state [ attached | unattached ] command to check information about the configured route-filter.
Run the display bgp routing-table [ peer ipv4-address advertised-routes [ statistics ] ] command to check the routes in the BGP routing table.