The content of the ORF value is determined by the ORF-type setting. An ORF type of NLRI-based filtering (type 1) uses the following actions:
■ ADD: Adds a line to a prefix-list filter on the remote peer
■ DELETE: Removes a line from a filter that was previously installed on a remote peer
■ DELETE ALL: Removes all previously installed filters on the remote peer
For each filter entry, there is a match component that specifies either PERMIT or DENY. A PERMIT asks the peer to send updates with routes that match the set of entries as specified in the ORF. DENY specifies that the remote peer should not send updates for the entries matching those specified in the ORF.
For prefixes specified with a match component of PERMIT, the remote peer is asked to pass a prefix with a scope of EXACT (an exact match) or REFINE (its subnets).
Also contained within the ORF message is the when-to-refresh field. A router can set this field to IMMEDIATE (asking the remote peer to refresh as soon as it has finished processing the ORF message) or DEFER (asking the remote peer to wait until it receives a subsequent route refresh message with the same AFI/SAFI).
3-68 Configuring BGP on Cisco Routers (BGP) v3.2 © 2005, Cisco Systems, Inc.
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