Subcodes for BGP Cease Notification Message
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Extracted elements (11)
The backoff/damping recommendation for specific Cease subcodes (Administrative Shutdown, Peer De-configured, Connection Rejected, Out of Resources) is intended to prevent rapid BGP connection retry storms when the remote side has signaled it is administratively or resource-constrained, aiding network stability.
A BGP speaker MAY send a NOTIFICATION message with Error Code Cease and subcode 'Out of Resources' when running out of resources (e.g., memory) and deciding to reset a session.
A BGP speaker MUST send a NOTIFICATION message with Error Code Cease and subcode 'Maximum Number of Prefixes Reached' when the number of address prefixes received from a neighbor exceeds the locally configured upper bound.
A BGP speaker SHOULD send a NOTIFICATION message with Error Code Cease and subcode 'Other Configuration Change' when resetting peering due to a configuration change not covered by the other defined subcodes.
An implementation SHOULD impose an upper bound on consecutive automatic BGP connection retries; once reached, automatic retries stop until administrative intervention sets AllowAutomaticStart to FALSE.
It is RECOMMENDED that a BGP speaker behave as though the DampPeerOscillations attribute were true when re-trying a BGP connection after receiving a Cease NOTIFICATION with subcodes 'Administrative Shutdown', 'Peer De-configured', 'Connection Rejected', or 'Out of Resources'.
When sending a Cease NOTIFICATION as a result of connection collision resolution (per BGP-4), the subcode SHOULD be set to 'Connection Collision Resolution'.
Eight subcodes are defined for the BGP Cease NOTIFICATION message: 1=Maximum Number of Prefixes Reached, 2=Administrative Shutdown, 3=Peer De-configured, 4=Administrative Reset, 5=Connection Rejected, 6=Other Configuration Change, 7=Connection Collision Resolution, 8=Out of Resources.
This document defines subcodes 1–8 for the BGP Cease NOTIFICATION message. Future assignments are to be made via the Standards Action process (RFC 2434) or the Early IANA Allocation process (RFC 4020), consisting of a name and value.
This extension to BGP does not change the underlying security issues inherent in the existing BGP protocol; no new security concerns are introduced.
The optional Data field for the 'Maximum Number of Prefixes Reached' subcode contains: AFI (2 octets), SAFI (1 octet), and Prefix upper bound (4 octets), with AFI/SAFI semantics as defined in RFC 2858 Section 7.