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CLI-based Configuration Guide - IP Unicast Routing

AR100, AR120, AR150, AR160, AR200, AR1200, AR2200, AR3200, and AR3600 V200R009

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The prefix-based BGP outbound route filtering (ORF) capability to advertise required BGP routes. BGP ORF allows a device to send prefix-based import policies in a Route-refresh message to BGP peers. BGP peers construct export policies based on these import policies to filter routes before sending these routes, which has the following advantages:
  • Prevents the local device from receiving a large number of unnecessary routes.
  • Reduces CPU usage of the local device.
  • Simplifies the configuration of BGP peers.
  • Improves link bandwidth efficiency.


BGP ORF applies to the scenario when a device wants BGP peers to send only required routes, and BGP peers do not want to maintain different export policies for different devices.

Figure 9-11 Inter-AS EBGP peers

As shown in Figure 9-11, after negotiating the prefix-based ORF capability with RouterB, RouterA adds the local prefix-based import policies to a Route-refresh message and sends the message to RouterB. RouterB constructs export policies based on the received Route-refresh message and sends required routes to RouterA using a Route-refresh message. RouterA receives only required routes, and RouterB does not need to maintain routing policies. This reduces the configuration workload.

Figure 9-12 Intra-AS route reflector

As shown in Figure 9-12, there is a route reflector (RR) in AS 100. RouterA and RouterB are the clients of the RR. RouterA, RouterB, and the RR negotiate the prefix-based ORF capability. RouterA and RouterB then add the local prefix-based import policies to Route-refresh messages and send the messages to the RR. The RR constructs export policies based on the received import policies and reflects required routes in Route-refresh messages to RouterA and RouterB. RouterA and RouterB receive only required routes, and the RR does not need to maintain routing policies. This reduces the configuration workload.

Updated: 2019-05-17

Document ID: EDOC1000174069

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