draft-ietf-idr-bgp-gr-notification-14.txt   draft-ietf-idr-bgp-gr-notification-15.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 8, 2018 J. Scudder Expires: October 12, 2018 J. Scudder
J. Haas J. Haas
Juniper Networks Juniper Networks
April 6, 2018 April 10, 2018
Notification Message support for BGP Graceful Restart Notification Message support for BGP Graceful Restart
draft-ietf-idr-bgp-gr-notification-14.txt draft-ietf-idr-bgp-gr-notification-15.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 8, 2018. This Internet-Draft will expire on October 12, 2018.
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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1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
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. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 6. Management Considerations . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
9. Normative References . . . . . . . . . . . . . . . . . . . . 8 9. Security Considerations . . . . . . . . . . . . . . . . . . . 8
10. 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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[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). This
also implies support for the format for a BGP NOTIFICATION Cease also implies support for the format for a BGP NOTIFICATION Cease
message defined in [RFC4486]. message defined in [RFC4486].
If a BGP speaker which previously advertised the "N" bit opens a new If a BGP speaker that previously advertised a given set of Graceful
session without advertising that bit, normal BGP Graceful Restart Restart parameters opens a new session with a different set of
procedures documented in [RFC4724] apply. parameters, these new parameters apply once the session has
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 7. We refer to a BGP NOTIFICATION Cease message with the Section 8. 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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5.2. Interaction With Other Specifications 5.2. Interaction With Other Specifications
"BGP Administrative Shutdown Communication" [RFC8203] specifies use "BGP Administrative Shutdown Communication" [RFC8203] specifies use
of the data portion of the Administrative Shutdown or Administrative of the data portion of the Administrative Shutdown or Administrative
Reset Cease to convey a short message. When [RFC8203] is used in Reset Cease to convey a short message. When [RFC8203] is used in
conjunction with Hard Reset, the subcode of the outermost Cease MUST conjunction with Hard Reset, the subcode of the outermost Cease MUST
be Hard Reset, with the Administrative Shutdown or Reset Cease be Hard Reset, with the Administrative Shutdown or Reset Cease
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. Acknowledgements 6. Management Considerations
When reporting a Hard Reset to network management, the error code and
subcode reported MUST be Cease, Hard Reset. If the network
management layer in use permits it, the information carried in the
Data portion SHOULD be reported as well.
7. 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, Paul Mattes, Robert
Raszuk, and Alvaro Retana for their review and comments. Raszuk, and Alvaro Retana for their review and comments.
7. IANA Considerations 8. 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
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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 | | |
+--------------+------------------+------------+-----------+ +--------------+------------------+------------+-----------+
8. Security Considerations 9. 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.
9. Normative References 10. 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>.
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