draft-ietf-idr-bgp-gr-notification-15.txt   draft-ietf-idr-bgp-gr-notification-16.txt 
Internet Engineering Task Force K. Patel Internet Engineering Task Force K. Patel
Internet-Draft Arrcus Internet-Draft Arrcus
Updates: 4724 (if approved) R. Fernando Updates: 4724 (if approved) R. Fernando
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: October 12, 2018 J. Scudder Expires: May 31, 2019 J. Scudder
J. Haas J. Haas
Juniper Networks Juniper Networks
April 10, 2018 November 27, 2018
Notification Message support for BGP Graceful Restart Notification Message support for BGP Graceful Restart
draft-ietf-idr-bgp-gr-notification-15.txt draft-ietf-idr-bgp-gr-notification-16.txt
Abstract Abstract
The BGP Graceful Restart mechanism defined in RFC 4724 limits the The BGP Graceful Restart mechanism defined in RFC 4724 limits the
usage of BGP Graceful Restart to BGP protocol messages other than a usage of BGP Graceful Restart to BGP protocol messages other than a
BGP NOTIFICATION message. This document updates RFC 4724 by defining BGP NOTIFICATION message. This document updates RFC 4724 by defining
an extension that permits the Graceful Restart procedures to be an extension that permits the Graceful Restart procedures to be
performed when the BGP speaker receives a BGP NOTIFICATION Message or performed when the BGP speaker receives a BGP NOTIFICATION Message or
the Hold Time expires. This document also defines a new BGP the Hold Time expires. This document also defines a new BGP
NOTIFICATION Cease Error subcode whose effect is to request a full NOTIFICATION Cease Error subcode whose effect is to request a full
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 12, 2018. This Internet-Draft will expire on May 31, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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2. Modifications to BGP Graceful Restart Capability . . . . . . 3 2. Modifications to BGP Graceful Restart Capability . . . . . . 3
3. BGP Hard Reset Subcode . . . . . . . . . . . . . . . . . . . 3 3. BGP Hard Reset Subcode . . . . . . . . . . . . . . . . . . . 3
3.1. Sending a Hard Reset . . . . . . . . . . . . . . . . . . 4 3.1. Sending a Hard Reset . . . . . . . . . . . . . . . . . . 4
3.2. Receiving a Hard Reset . . . . . . . . . . . . . . . . . 4 3.2. Receiving a Hard Reset . . . . . . . . . . . . . . . . . 4
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Rules for the Receiving Speaker . . . . . . . . . . . . . 5 4.1. Rules for the Receiving Speaker . . . . . . . . . . . . . 5
5. Use of Hard Reset . . . . . . . . . . . . . . . . . . . . . . 6 5. Use of Hard Reset . . . . . . . . . . . . . . . . . . . . . . 6
5.1. When to Send Hard Reset . . . . . . . . . . . . . . . . . 6 5.1. When to Send Hard Reset . . . . . . . . . . . . . . . . . 6
5.2. Interaction With Other Specifications . . . . . . . . . . 7 5.2. Interaction With Other Specifications . . . . . . . . . . 7
6. Management Considerations . . . . . . . . . . . . . . . . . . 7 6. Management Considerations . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 7. Operational Considerations . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
9. Security Considerations . . . . . . . . . . . . . . . . . . . 8 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
10. Normative References . . . . . . . . . . . . . . . . . . . . 8 10. Security Considerations . . . . . . . . . . . . . . . . . . . 8
11. Normative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
For many classes of errors, the BGP protocol must send a NOTIFICATION For many classes of errors, the BGP protocol must send a NOTIFICATION
message and reset the peering session to handle the error condition. message and reset the peering session to handle the error condition.
The BGP Graceful Restart extension defined in [RFC4724] requires that The BGP Graceful Restart extension defined in [RFC4724] requires that
normal BGP procedures defined in [RFC4271] be followed when a normal BGP procedures defined in [RFC4271] be followed when a
NOTIFICATION message is sent or received. This document defines an NOTIFICATION message is sent or received. This document defines an
extension to BGP Graceful Restart that permits the Graceful Restart extension to BGP Graceful Restart that permits the Graceful Restart
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BGP session is reset, both speakers operate as "Receiving Speakers" BGP session is reset, both speakers operate as "Receiving Speakers"
according to [RFC4724], meaning they retain each other's routes. according to [RFC4724], meaning they retain each other's routes.
This is also true for HOLDTIME expiration. The functionality can be This is also true for HOLDTIME expiration. The functionality can be
defeated using a "Hard Reset" subcode for the BGP NOTIFICATION Cease defeated using a "Hard Reset" subcode for the BGP NOTIFICATION Cease
Error code. If a Hard Reset is used, a full session reset is Error code. If a Hard Reset is used, a full session reset is
performed. performed.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in RFC 2119 [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Modifications to BGP Graceful Restart Capability 2. Modifications to BGP Graceful Restart Capability
The BGP Graceful Restart Capability is augmented to signal the The BGP Graceful Restart Capability is augmented to signal the
Graceful Restart support for BGP NOTIFICATION messages. The Restart Graceful Restart support for BGP NOTIFICATION messages. The Restart
Flags field is augmented as follows (following the diagram from Flags field is augmented as follows (following the diagram from
section 3 of [RFC4724]): section 3 of [RFC4724]):
Restart Flags: Restart Flags:
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|R|N| | |R|N| |
+-+-+-+-+ +-+-+-+-+
The most significant ("Restart State", or "R") bit is defined in The most significant ("Restart State", or "R") bit is defined in
[RFC4724]. [RFC4724].
The second most significant bit ("N") is defined as the BGP Graceful The second most significant bit ("N") is defined as the BGP Graceful
Notification bit, which is used to indicate Graceful Restart support Notification bit, which is used to indicate Graceful Restart support
for BGP NOTIFICATION messages. A BGP speaker indicates support for for BGP NOTIFICATION messages. A BGP speaker indicates support for
the procedures of this document, by advertising a Graceful Restart the procedures of this document, by advertising a Graceful Restart
Capability with its Graceful NOTIFICATION bit set (value 1). This Capability with its Graceful Notification bit set (value 1).
also implies support for the format for a BGP NOTIFICATION Cease
message defined in [RFC4486].
If a BGP speaker that previously advertised a given set of Graceful If a BGP speaker that previously advertised a given set of Graceful
Restart parameters opens a new session with a different set of Restart parameters opens a new session with a different set of
parameters, these new parameters apply once the session has parameters, these new parameters apply once the session has
transitioned into ESTABLISHED state. transitioned into ESTABLISHED state.
3. BGP Hard Reset Subcode 3. BGP Hard Reset Subcode
We define a new BGP NOTIFICATION Cease message subcode, called the We define a new BGP NOTIFICATION Cease message subcode, called the
BGP Hard Reset Subcode. The value of this subcode is discussed in BGP Hard Reset Subcode. The value of this subcode is discussed in
Section 8. We refer to a BGP NOTIFICATION Cease message with the Section 9. We refer to a BGP NOTIFICATION Cease message with the
Hard Reset subcode as a Hard Reset message, or just a Hard Reset. Hard Reset subcode as a Hard Reset message, or just a Hard Reset.
When the "N" bit has been exchanged by two peers, to distinguish them When the "N" bit has been exchanged by two peers, to distinguish them
from Hard Reset we refer to any NOTIFICATION messages other than Hard from Hard Reset we refer to any NOTIFICATION messages other than Hard
Reset as "Graceful", since such messages invoke Graceful Restart Reset as "Graceful", since such messages invoke Graceful Restart
semantics. semantics.
3.1. Sending a Hard Reset 3.1. Sending a Hard Reset
A Hard Reset message is used to indicate to a peer with which the A Hard Reset message is used to indicate to a peer with which the
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encapsulated within. The encapsulated administrative shutdown encapsulated within. The encapsulated administrative shutdown
message MUST subsequently be processed according to [RFC8203]. message MUST subsequently be processed according to [RFC8203].
6. Management Considerations 6. Management Considerations
When reporting a Hard Reset to network management, the error code and When reporting a Hard Reset to network management, the error code and
subcode reported MUST be Cease, Hard Reset. If the network subcode reported MUST be Cease, Hard Reset. If the network
management layer in use permits it, the information carried in the management layer in use permits it, the information carried in the
Data portion SHOULD be reported as well. Data portion SHOULD be reported as well.
7. Acknowledgements 7. Operational Considerations
Note that long (or infinite) retention time may cause operational
issues, and should be enabled with care.
8. Acknowledgements
The authors would like to thank Jim Uttaro for the suggestion, and The authors would like to thank Jim Uttaro for the suggestion, and
Emmanuel Baccelli, Bruno Decraene, Chris Hall, Paul Mattes, Robert Emmanuel Baccelli, Bruno Decraene, Chris Hall, Warren Kumari, Paul
Raszuk, and Alvaro Retana for their review and comments. Mattes, Robert Raszuk, and Alvaro Retana for their review and
comments.
8. IANA Considerations 9. IANA Considerations
IANA has temporarily assigned subcode 9, named "Hard Reset", in the IANA has temporarily assigned subcode 9, named "Hard Reset", in the
"BGP Cease NOTIFICATION message subcodes" registry. Upon publication "BGP Cease NOTIFICATION message subcodes" registry. Upon publication
of this document as an RFC, IANA is requested to make this allocation of this document as an RFC, IANA is requested to make this allocation
permanent. permanent.
IANA is requested to establish a registry within the "Border Gateway IANA is requested to establish a registry within the "Border Gateway
Protocol (BGP) Parameters" grouping, to be called "BGP Graceful Protocol (BGP) Parameters" grouping, to be called "BGP Graceful
Restart Flags". The Registration Procedure should be Standards Restart Flags". The Registration Procedure should be Standards
Action, the reference this document and [RFC4724], and the initial Action, the reference this document and [RFC4724], and the initial
values as follows: values as follows:
+--------------+---------------+------------+---------------+ +--------------+---------------+------------+---------------+
| Bit Position | Name | Short Name | Reference | | Bit Position | Name | Short Name | Reference |
+--------------+---------------+------------+---------------+ +--------------+---------------+------------+---------------+
| 0 | Restart State | R | [RFC4724] | | 0 | Restart State | R | [RFC4724] |
| 1 | Notification | N | this document | | 1 | Notification | N | this document |
| 2, 3 | unassigned | | | | 2, 3 | unassigned | | this document |
+--------------+---------------+------------+---------------+ +--------------+---------------+------------+---------------+
IANA is requested to establish a registry within the "Border Gateway IANA is requested to establish a registry within the "Border Gateway
Protocol (BGP) Parameters" grouping, to be called "BGP Graceful Protocol (BGP) Parameters" grouping, to be called "BGP Graceful
Restart Flags for Address Family". The Registration Procedure should Restart Flags for Address Family". The Registration Procedure should
be Standards Action, the reference this document and [RFC4724], and be Standards Action, the reference this document and [RFC4724], and
the initial values as follows: the initial values as follows:
+--------------+------------------+------------+-----------+ +--------------+------------------+------------+---------------+
| Bit Position | Name | Short Name | Reference | | Bit Position | Name | Short Name | Reference |
+--------------+------------------+------------+-----------+ +--------------+------------------+------------+---------------+
| 0 | Forwarding State | F | [RFC4724] | | 0 | Forwarding State | F | [RFC4724] |
| 1-7 | unassigned | | | | 1-7 | unassigned | | this document |
+--------------+------------------+------------+-----------+ +--------------+------------------+------------+---------------+
9. Security Considerations 10. Security Considerations
This specification doesn't change the basic security model inherent This specification doesn't change the basic security model inherent
in [RFC4724], with the exception that the protection against repeated in [RFC4724], with the exception that the protection against repeated
resets is relaxed. To mitigate the consequent risk that an attacker resets is relaxed. To mitigate the consequent risk that an attacker
could use repeated session resets to prevent stale routes from ever could use repeated session resets to prevent stale routes from ever
being deleted, we make the stale routes timer mandatory (in practice being deleted, we make the stale routes timer mandatory (in practice
it is already ubiquitous). To the extent [RFC4724] might be said to it is already ubiquitous). To the extent [RFC4724] might be said to
help defend against denials of service by making the control plane help defend against denials of service by making the control plane
more resilient, this extension may modestly increase that resilience; more resilient, this extension may modestly increase that resilience;
however, there are enough confounding and deployment-specific factors however, there are enough confounding and deployment-specific factors
that no general claims can be made. that no general claims can be made.
10. Normative References 11. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006, DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>. <https://www.rfc-editor.org/info/rfc4271>.
[RFC4486] Chen, E. and V. Gillet, "Subcodes for BGP Cease
Notification Message", RFC 4486, DOI 10.17487/RFC4486,
April 2006, <https://www.rfc-editor.org/info/rfc4486>.
[RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y. [RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724, Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
DOI 10.17487/RFC4724, January 2007, DOI 10.17487/RFC4724, January 2007,
<https://www.rfc-editor.org/info/rfc4724>. <https://www.rfc-editor.org/info/rfc4724>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8203] Snijders, J., Heitz, J., and J. Scudder, "BGP [RFC8203] Snijders, J., Heitz, J., and J. Scudder, "BGP
Administrative Shutdown Communication", RFC 8203, Administrative Shutdown Communication", RFC 8203,
DOI 10.17487/RFC8203, July 2017, DOI 10.17487/RFC8203, July 2017,
<https://www.rfc-editor.org/info/rfc8203>. <https://www.rfc-editor.org/info/rfc8203>.
Authors' Addresses Authors' Addresses
Keyur Patel Keyur Patel
Arrcus Arrcus
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