RFC 4486

Subcodes for BGP Cease Notification Message

📅 published April 2006, from ietf

RFC 4486: Subcodes for BGP Cease Notification Message 🎀

okay bestie, quick title-block tea ☕ This one is RFC 4486, written by E. Chen (Cisco Systems) and V. Gillet (France Telecom), in the Network Working Group. It's on the Standards Track and dates from April 2006. The title block doesn't list anything it obsoletes or updates. Now let's get into it 💅

Status of This Memo 📜

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice ©️

Abstract ✨

So this doc defines a bunch of subcodes for the BGP Cease NOTIFICATION message. The whole point is to give network operators more info so they can line up network events and figure out what's going wrong with BGP peering. Main character energy 🦋

1. Introduction 🌸

Same vibe as the abstract: this doc defines several subcodes for the BGP Cease NOTIFICATION message, giving network operators more information to correlate network events and diagnose BGP peering issues. It also recommends that a BGP speaker implement a backoff mechanism for retrying a BGP connection after the speaker receives a NOTIFICATION message with certain CEASE subcodes. Backoff is a must-have energy 🫶

2. Specification of Requirements 📋

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC-2119].

3. Subcode Definition 🎀

The following subcodes are defined for the Cease NOTIFICATION message:

   Subcode     Symbolic Name

      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

4. Subcode Usage 💖

Okay, this is the meaty part, so pay attention 👑

If a BGP speaker decides to terminate its peering with a neighbor because the number of address prefixes received from the neighbor exceeds a locally configured upper bound (as described in [BGP-4]), then the speaker MUST send to the neighbor a NOTIFICATION message with the Error Code Cease and the Error Subcode "Maximum Number of Prefixes Reached". The message MAY optionally include the Address Family information [BGP-MP] and the upper bound in the "Data" field, as shown in Figure 1, where the meaning and use of the <AFI, SAFI> tuple is the same as defined in [BGP-MP], Section 7.

              +-------------------------------+
              | AFI (2 octets)                |
              +-------------------------------+
              | SAFI (1 octet)                |
              +-------------------------------+
              | Prefix upper bound (4 octets) |
              +-------------------------------+

                 Figure 1: Optional Data Field

If a BGP speaker decides to administratively shut down its peering with a neighbor, then the speaker SHOULD send a NOTIFICATION message with the Error Code Cease and the Error Subcode "Administrative Shutdown".

If a BGP speaker decides to de-configure a peer, then the speaker SHOULD send a NOTIFICATION message with the Error Code Cease and the Error Subcode "Peer De-configured".

If a BGP speaker decides to administratively reset the peering with a neighbor, then the speaker SHOULD send a NOTIFICATION message with the Error Code Cease and the Error Subcode "Administrative Reset".

If a BGP speaker decides to disallow a BGP connection (e.g., the peer is not configured locally) after the speaker accepts a transport protocol connection, then the BGP speaker SHOULD send a NOTIFICATION message with the Error Code Cease and the Error Subcode "Connection Rejected".

If a BGP speaker decides to administratively reset the peering with a neighbor due to a configuration change other than the ones described above, then the speaker SHOULD send a NOTIFICATION message with the Error Code Cease and the Error Subcode "Other Configuration Change".

If a BGP speaker decides to send a NOTIFICATION message with the Error Code Cease as a result of the collision resolution procedure (as described in [BGP-4]), then the subcode SHOULD be set to "Connection Collision Resolution".

If a BGP speaker runs out of resources (e.g., memory) and decides to reset a session, then the speaker MAY send a NOTIFICATION message with the Error Code Cease and the Error Subcode "Out of Resources".

It is RECOMMENDED that a BGP speaker behave as though the DampPeerOscillations attribute [BGP-4] were true for this peer when retrying a BGP connection after the speaker receives a Cease NOTIFICATION message with a subcode of "Administrative Shutdown", "Peer De-configured", "Connection Rejected", or "Out of Resources". An implementation SHOULD impose an upper bound on the number of consecutive automatic retries. Once this bound is reached, the implementation would stop retrying any BGP connections until some administrative intervention, i.e., set the AllowAutomaticStart attribute [BGP-4] to FALSE. 🛑

5. IANA Considerations 🗂️

This document defines the subcodes 1 - 8 for the BGP Cease NOTIFICATION message. Future assignments are to be made using either the Standards Action process defined in [RFC-2434], or the Early IANA Allocation process defined in [RFC-4020]. Assignments consist of a name and the value.

6. Security Considerations 🚨

⚠️ Read this one carefully, no skipping!

This extension to BGP does not change the underlying security issues inherent in the existing BGP.

7. Acknowledgements 🫶

The authors would like to thank Yakov Rekhter, Pedro Marques, Andrew Lange, and Don Goodspeed for their review and suggestions. Shoutout to the reviewers 🌈

8. References 📚

8.1. Normative References

[BGP-4]    Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
           Protocol 4 (BGP-4)", RFC 4271, January 2006.

[BGP-MP]   Bates, T., Rekhter, Y., Chandra, R., and D. Katz,
           "Multiprotocol Extensions for BGP-4", RFC 2858, June 2000.

[RFC-2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
           IANA Considerations Section in RFCs", BCP 26, RFC 2434,
           October 1998.

[RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119, March 1997.

8.2. Informative References

[RFC-4020] Kompella, K. and A. Zinin, "Early IANA Allocation of
           Standards Track Code Points", BCP 100, RFC 4020, February
           2005.

Authors' Addresses 📮

Enke Chen
Cisco Systems, Inc.
170 W. Tasman Dr.
San Jose, CA 95134
USA

EMail: enkechen@cisco.com


Vincent Gillet
France Telecom Longues Distances
61, rue des Archives
75003 Paris FRANCE

EMail: vgi@opentransit.net

Full Copyright Statement 🌟

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