draft-ietf-idr-error-handling-14.txt   draft-ietf-idr-error-handling-15.txt 
Internet Engineering Task Force E. Chen, Ed. Internet Engineering Task Force E. Chen, Ed.
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Updates: 1997, 4271, 4360, 4456, 4760, J. Scudder, Ed. Updates: 1997, 4271, 4360, 4456, 4760, J. Scudder, Ed.
5543, 5701, 6368, 6790 (if Juniper Networks 5543, 5701, 6368 (if approved) Juniper Networks
approved) P. Mohapatra Intended status: Standards Track P. Mohapatra
Intended status: Standards Track Sproute Networks Expires: April 27, 2015 Sproute Networks
Expires: March 7, 2015 K. Patel K. Patel
Cisco Systems, Inc. Cisco Systems, Inc.
September 3, 2014 October 24, 2014
Revised Error Handling for BGP UPDATE Messages Revised Error Handling for BGP UPDATE Messages
draft-ietf-idr-error-handling-14 draft-ietf-idr-error-handling-15
Abstract Abstract
According to the base BGP specification, a BGP speaker that receives According to the base BGP specification, a BGP speaker that receives
an UPDATE message containing a malformed attribute is required to an UPDATE message containing a malformed attribute is required to
reset the session over which the offending attribute was received. reset the session over which the offending attribute was received.
This behavior is undesirable as a session reset would impact not only This behavior is undesirable as a session reset would impact not only
routes with the offending attribute, but also other valid routes routes with the offending attribute, but also other valid routes
exchanged over the session. This document partially revises the exchanged over the session. This document partially revises the
error handling for UPDATE messages, and provides guidelines for the error handling for UPDATE messages, and provides guidelines for the
authors of documents defining new attributes. Finally, it revises authors of documents defining new attributes. Finally, it revises
the error handling procedures for a number of existing attributes. the error handling procedures for a number of existing attributes.
This document updates error handling for RFCs 1997, 4271, 4360, 4456, This document updates error handling for RFCs 1997, 4271, 4360, 4456,
4760, 5543, 5701, 6368 and 6790. 4760, 5543, 5701 and 6368.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 March 7, 2015. This Internet-Draft will expire on April 27, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://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
skipping to change at page 2, line 52 skipping to change at page 2, line 52
5.3. Syntactic Correctness of NLRI Fields . . . . . . . . . . 8 5.3. Syntactic Correctness of NLRI Fields . . . . . . . . . . 8
5.4. Typed NLRI . . . . . . . . . . . . . . . . . . . . . . . 8 5.4. Typed NLRI . . . . . . . . . . . . . . . . . . . . . . . 8
6. Operational Considerations . . . . . . . . . . . . . . . . . 9 6. Operational Considerations . . . . . . . . . . . . . . . . . 9
7. Error Handling Procedures for Existing Attributes . . . . . . 10 7. Error Handling Procedures for Existing Attributes . . . . . . 10
7.1. ORIGIN . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. ORIGIN . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.2. AS_PATH . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.2. AS_PATH . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.3. NEXT_HOP . . . . . . . . . . . . . . . . . . . . . . . . 11 7.3. NEXT_HOP . . . . . . . . . . . . . . . . . . . . . . . . 11
7.4. MULTI_EXIT_DISC . . . . . . . . . . . . . . . . . . . . . 11 7.4. MULTI_EXIT_DISC . . . . . . . . . . . . . . . . . . . . . 11
7.5. LOCAL_PREF . . . . . . . . . . . . . . . . . . . . . . . 11 7.5. LOCAL_PREF . . . . . . . . . . . . . . . . . . . . . . . 11
7.6. ATOMIC_AGGREGATE . . . . . . . . . . . . . . . . . . . . 11 7.6. ATOMIC_AGGREGATE . . . . . . . . . . . . . . . . . . . . 11
7.7. AGGREGATOR . . . . . . . . . . . . . . . . . . . . . . . 11 7.7. AGGREGATOR . . . . . . . . . . . . . . . . . . . . . . . 12
7.8. Community . . . . . . . . . . . . . . . . . . . . . . . . 12 7.8. Community . . . . . . . . . . . . . . . . . . . . . . . . 12
7.9. ORIGINATOR_ID . . . . . . . . . . . . . . . . . . . . . . 12 7.9. ORIGINATOR_ID . . . . . . . . . . . . . . . . . . . . . . 12
7.10. CLUSTER_LIST . . . . . . . . . . . . . . . . . . . . . . 12 7.10. CLUSTER_LIST . . . . . . . . . . . . . . . . . . . . . . 12
7.11. MP_REACH_NLRI . . . . . . . . . . . . . . . . . . . . . . 13 7.11. MP_REACH_NLRI . . . . . . . . . . . . . . . . . . . . . . 13
7.12. MP_UNREACH_NLRI . . . . . . . . . . . . . . . . . . . . . 13 7.12. MP_UNREACH_NLRI . . . . . . . . . . . . . . . . . . . . . 13
7.13. Traffic Engineering path attribute . . . . . . . . . . . 13 7.13. Traffic Engineering path attribute . . . . . . . . . . . 13
7.14. Extended Community . . . . . . . . . . . . . . . . . . . 13 7.14. Extended Community . . . . . . . . . . . . . . . . . . . 13
7.15. IPv6 Address Specific BGP Extended Community Attribute . 14 7.15. IPv6 Address Specific BGP Extended Community Attribute . 14
7.16. BGP Entropy Label Capability Attribute . . . . . . . . . 14 7.16. ATTR_SET . . . . . . . . . . . . . . . . . . . . . . . . 14
7.17. ATTR_SET . . . . . . . . . . . . . . . . . . . . . . . . 14 8. Guidance for Authors of BGP Specifications . . . . . . . . . 14
8. Guidance for Authors of BGP Specifications . . . . . . . . . 15
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
10. Security Considerations . . . . . . . . . . . . . . . . . . . 15 10. Security Considerations . . . . . . . . . . . . . . . . . . . 15
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
12.1. Normative References . . . . . . . . . . . . . . . . . . 16 12.1. Normative References . . . . . . . . . . . . . . . . . . 16
12.2. Informative References . . . . . . . . . . . . . . . . . 17 12.2. Informative References . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
According to the base BGP specification [RFC4271], a BGP speaker that According to the base BGP specification [RFC4271], a BGP speaker that
receives an UPDATE message containing a malformed attribute is receives an UPDATE message containing a malformed attribute is
required to reset the session over which the offending attribute was required to reset the session over which the offending attribute was
received. This behavior is undesirable as a session reset would received. This behavior is undesirable as a session reset would
skipping to change at page 4, line 10 skipping to change at page 4, line 10
maintaining protocol correctness to the extent possible. This can be maintaining protocol correctness to the extent possible. This can be
achieved largely by maintaining the established session and keeping achieved largely by maintaining the established session and keeping
the valid routes exchanged, but removing the routes carried in the the valid routes exchanged, but removing the routes carried in the
malformed UPDATE from the routing system. malformed UPDATE from the routing system.
This document partially revises the error handling for UPDATE This document partially revises the error handling for UPDATE
messages, and provides guidelines for the authors of documents messages, and provides guidelines for the authors of documents
defining new attributes. Finally, it revises the error handling defining new attributes. Finally, it revises the error handling
procedures for a number of existing attributes. Specifically, the procedures for a number of existing attributes. Specifically, the
error handling procedures of [RFC1997], [RFC4271], [RFC4360], error handling procedures of [RFC1997], [RFC4271], [RFC4360],
[RFC4456], [RFC4760], [RFC5543], [RFC5701], [RFC6368] and [RFC6790] [RFC4456], [RFC4760], [RFC5543], [RFC5701], and [RFC6368] are
are revised. revised.
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", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Error-Handling Approaches 2. Error-Handling Approaches
In this document we refer to four different approaches to handling In this document we refer to four different approaches to handling
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update, and could cause invalid routes to be kept. update, and could cause invalid routes to be kept.
Because of these potential issues, a BGP speaker MUST provide Because of these potential issues, a BGP speaker MUST provide
debugging facilities to permit issues caused by a malformed attribute debugging facilities to permit issues caused by a malformed attribute
to be diagnosed. At a minimum, such facilities MUST include logging to be diagnosed. At a minimum, such facilities MUST include logging
an error listing the NLRI involved, and containing the entire an error listing the NLRI involved, and containing the entire
malformed UPDATE message when such an attribute is detected. The malformed UPDATE message when such an attribute is detected. The
malformed UPDATE message SHOULD be analyzed, and the root cause malformed UPDATE message SHOULD be analyzed, and the root cause
SHOULD be investigated. SHOULD be investigated.
Section 8 mentions that attribute discard should not be used in cases
where "the attribute in question has or may have an effect on route
selection." Although all cases that specify attribute discard in
this document do not affect route selection by default, in principle
routing policies could be written that affect selection based on such
an attribute. Operators should take care when writing such policies
to consider the possible consequences of an attribute discard. (In
general, as long as such policies are only applied to external BGP
sessions, correctness issues are not expected to arise.)
7. Error Handling Procedures for Existing Attributes 7. Error Handling Procedures for Existing Attributes
In the following subsections, we elaborate on the conditions for In the following subsections, we elaborate on the conditions for
error-checking various path attributes, and specify what approach(es) error-checking various path attributes, and specify what approach(es)
should be used to handle malformations. It is possible that should be used to handle malformations. It is possible that
implementations may apply other error checks not contemplated here. implementations may apply other error checks not contemplated here.
If so, the error handling approach given here should generally be If so, the error handling approach given here should generally be
applied. applied.
This section addresses all path attributes that are defined at the This section addresses all path attributes that are defined at the
time of this writing, that were not defined with error-handling time of this writing, that were not defined with error-handling
consistent with Section 8, and that are not marked as "deprecated" in consistent with Section 8, and that are not marked as "deprecated" in
[IANA-BGP-ATTRS]. Attributes 17 (AS4_PATH), 18 (AS4_AGGREGATOR), 22 [IANA-BGP-ATTRS]. Attributes 17 (AS4_PATH), 18 (AS4_AGGREGATOR), 22
(PMSI_TUNNEL), 23 (Tunnel Encapsulation Attribute), 26 (AIGP), 27 (PE (PMSI_TUNNEL), 23 (Tunnel Encapsulation Attribute), 26 (AIGP), 27 (PE
Distinguisher Labels) and 29 (BGP-LS Attribute) do have error- Distinguisher Labels) and 29 (BGP-LS Attribute) do have error-
handling consistent with Section 8 and thus are not further discussed handling consistent with Section 8 and thus are not further discussed
herein. Attributes 11 (DPA), 12 (ADVERTISER), 13 (RCID_PATH / herein. Attributes 11 (DPA), 12 (ADVERTISER), 13 (RCID_PATH /
CLUSTER_ID), 19 (SAFI Specific Attribute), 20 (Connector Attribute) CLUSTER_ID), 19 (SAFI Specific Attribute), 20 (Connector Attribute),
and 21 (AS_PATHLIMIT) are deprecated and thus are not further 21 (AS_PATHLIMIT) and 28 (BGP Entropy Label Capability Attribute) are
discussed herein. deprecated and thus are not further discussed herein.
7.1. ORIGIN 7.1. ORIGIN
The attribute is considered malformed if its length is not 1, or it The attribute is considered malformed if its length is not 1, or it
has an undefined value [RFC4271]. has an undefined value [RFC4271].
An UPDATE message with a malformed ORIGIN attribute SHALL be handled An UPDATE message with a malformed ORIGIN attribute SHALL be handled
using the approach of "treat-as-withdraw". using the approach of "treat-as-withdraw".
7.2. AS_PATH 7.2. AS_PATH
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The IPv6 Address Specific Extended Community attribute SHALL be The IPv6 Address Specific Extended Community attribute SHALL be
considered malformed if its length is not a nonzero multiple of 20. considered malformed if its length is not a nonzero multiple of 20.
An UPDATE message with a malformed IPv6 Address Specific Extended An UPDATE message with a malformed IPv6 Address Specific Extended
Community attribute SHALL be handled using the approach of "treat-as- Community attribute SHALL be handled using the approach of "treat-as-
withdraw". withdraw".
Note that a BGP speaker MUST NOT treat an unrecognized IPv6 Address Note that a BGP speaker MUST NOT treat an unrecognized IPv6 Address
Specific Extended Community Type or Sub-Type as an error. Specific Extended Community Type or Sub-Type as an error.
7.16. BGP Entropy Label Capability Attribute 7.16. ATTR_SET
The error handling of [RFC6790] is revised as follows.
No syntax errors are defined for the Entropy Label Capability
attribute (ELCA). However, if any implementation does for some local
reason determine that a syntax error exists with the ELCA, the error
SHALL be handled using the approach of "attribute discard".
7.17. ATTR_SET
The final paragraph of Section 5 of [RFC6368] is revised as follows: The final paragraph of Section 5 of [RFC6368] is revised as follows:
Old Text: Old Text:
An UPDATE message with a malformed ATTR_SET attribute SHALL be An UPDATE message with a malformed ATTR_SET attribute SHALL be
handled as follows. If its Partial flag is set and its handled as follows. If its Partial flag is set and its
Neighbor-Complete flag is clear, the UPDATE is treated as a Neighbor-Complete flag is clear, the UPDATE is treated as a
route withdraw as discussed in [OPT-TRANS-BGP]. Otherwise route withdraw as discussed in [OPT-TRANS-BGP]. Otherwise
(i.e., Partial flag is clear or Neighbor-Complete is set), the (i.e., Partial flag is clear or Neighbor-Complete is set), the
skipping to change at page 16, line 48 skipping to change at page 16, line 45
Engineering Attribute", RFC 5543, May 2009. Engineering Attribute", RFC 5543, May 2009.
[RFC5701] Rekhter, Y., "IPv6 Address Specific BGP Extended Community [RFC5701] Rekhter, Y., "IPv6 Address Specific BGP Extended Community
Attribute", RFC 5701, November 2009. Attribute", RFC 5701, November 2009.
[RFC6368] Marques, P., Raszuk, R., Patel, K., Kumaki, K., and T. [RFC6368] Marques, P., Raszuk, R., Patel, K., Kumaki, K., and T.
Yamagata, "Internal BGP as the Provider/Customer Edge Yamagata, "Internal BGP as the Provider/Customer Edge
Protocol for BGP/MPLS IP Virtual Private Networks (VPNs)", Protocol for BGP/MPLS IP Virtual Private Networks (VPNs)",
RFC 6368, September 2011. RFC 6368, September 2011.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, November 2012.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793, December Autonomous System (AS) Number Space", RFC 6793, December
2012. 2012.
12.2. Informative References 12.2. Informative References
[I-D.ietf-l2vpn-evpn] [I-D.ietf-l2vpn-evpn]
Sajassi, A., Aggarwal, R., Bitar, N., Isaac, A., and J. Sajassi, A., Aggarwal, R., Bitar, N., Isaac, A., and J.
Uttaro, "BGP MPLS Based Ethernet VPN", draft-ietf-l2vpn- Uttaro, "BGP MPLS Based Ethernet VPN", draft-ietf-l2vpn-
evpn-07 (work in progress), May 2014. evpn-11 (work in progress), October 2014.
[RFC5549] Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network [RFC5549] Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network
Layer Reachability Information with an IPv6 Next Hop", RFC Layer Reachability Information with an IPv6 Next Hop", RFC
5549, May 2009. 5549, May 2009.
[RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
Encodings and Procedures for Multicast in MPLS/BGP IP Encodings and Procedures for Multicast in MPLS/BGP IP
VPNs", RFC 6514, February 2012. VPNs", RFC 6514, February 2012.
[RFC7117] Aggarwal, R., Kamite, Y., Fang, L., Rekhter, Y., and C. [RFC7117] Aggarwal, R., Kamite, Y., Fang, L., Rekhter, Y., and C.
 End of changes. 14 change blocks. 
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