Internet DRAFT - draft-ietf-grow-ops-reqs-for-bgp-error-handling
draft-ietf-grow-ops-reqs-for-bgp-error-handling
Internet Engineering Task Force R. Shakir
Internet-Draft BT
Intended status: Informational November 9, 2014
Expires: May 13, 2015
Operational Requirements for Enhanced Error Handling Behaviour in BGP-4
draft-ietf-grow-ops-reqs-for-bgp-error-handling-07
Abstract
BGP-4 is utilised as a key intra- and inter-Autonomous System routing
protocol in modern IP networks. The failure modes as defined by the
original protocol standards are based on a number of assumptions
around the impact of session failure. Numerous incidents both in the
global Internet routing table and within Service Provider networks
have been caused by strict handling of a single invalid UPDATE
message causing large-scale failures in one or more Autonomous
Systems.
This memo describes the current use of BGP-4 within Service Provider
networks, and outlines a set of requirements for further work to
enhance the mechanisms available to a BGP-4 implementation when
erroneous data is detected. Whilst this document does not provide
specification of any standard, it is intended as an overview of a set
of enhancements to BGP-4 to improve the protocol's robustness to suit
its current deployment.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 13, 2015.
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Copyright Notice
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Table of Contents
1. Requirements Language . . . . . . . . . . . . . . . . . . . . 2
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Role of BGP-4 in Service Provider Networks . . . . . . . 3
2.2. Service Requirements for Amended BGP Error Handling . . . 4
3. Classes of Errors within UPDATE Messages . . . . . . . . . . 6
3.1. Characteristics of Session Scope Errors . . . . . . . . . 6
3.2. Characteristics of Message Scope Errors . . . . . . . . . 7
3.3. Characteristics of Attribute Scope Errors . . . . . . . . 7
3.4. Avoiding Session Scope Errors . . . . . . . . . . . . . . 7
3.5. Future Attributes introduced to BGP . . . . . . . . . . . 8
4. Error Handling for Non-Critical Errors . . . . . . . . . . . 8
4.1. NLRI-level Error Handling Requirements . . . . . . . . . 8
4.1.1. Notifying the Remote Peer of Non-Critical Errors . . 9
4.2. Recovering RIB Consistency following NLRI-level Error
Handling . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Error Handling for Critical Errors . . . . . . . . . . . . . 10
5.1. Long-Lived Critical Errors . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informational References . . . . . . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14
1. Requirements Language
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 [RFC2119].
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2. Problem Statement
BGP has developed into a key intra- and inter-domain routing
protocol, deployed within both the Internet and private networks.
The changing deployments of the protocol have resulted in increased
demand for robustness of the routing system - with the error handling
behaviour defined in [RFC4271] having been shown to have caused
numerous incidents within live network deployments. This document
intends to provide an overview of the current deployment cases for
BGP-4, and define a set of requirements (from the perspective of a
network operator) for enhancing error handling within the protocol.
2.1. Role of BGP-4 in Service Provider Networks
BGP was designed as an inter-autonomous system (AS) routing protocol.
Many of the error handling mechanisms within the protocol are defined
in order to be guarantee consistency and correctness of information
between two neighbouring speakers. The assumption is made that each
AS operates with many adjacencies, each propagating a relatively
small amount of routing information. Through focusing on information
consistency, the protocol specification prefers failure of an
individual routing adjacency to maintaining reachability to all NLRI
propagated through a particular neighbour, with the expectation that
alternate, less direct, paths can be selected where a failure occurs.
These assumptions resulted in the specification made in [RFC4271]
whereby the receipt of an erroneous UPDATE message is reacted to by
sending a NOTIFICATION message, and tearing down the adjacency with
the remote speaker from whom the error was observed.
BGP's deployments have evolved with the growth of IP-based services.
Historically, a network would deploy an interior gateway protocol
(IGP) to carry infrastructure and customer routes, and utilise an
external gateway protocol (EGP) such as BGP to propagate routes to
other autonomous systems. However, within modern deployments to
ensure route convergence within an AS is within acceptable time
bounds the amount of information within the IGP has been minimised
(typically to only infrastructure routes). iBGP is then utilised to
carry both internal, customer and external routes within an AS. As
such, this has resulted in BGP having become an IGP, with traditional
IGPs providing only reachability between nodes within the AS for
packet forwarding, and to establish iBGP sessions. This change in
role within the overall architecture of an AS has resulted in an
increased robustness requirement for BGP, with the expectation of a
similar level of robustness to that of an IGP being set. The loss of
an iBGP session can result in significant levels of unreachability
internally to an AS, especially since there are typically limited
(when compared to the Internet) signalling and forwarding paths
available.
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The volume and nature of the information carried within BGP has also
changed - it has become the ubiquitous means through which service
information can be propagated between devices. For instance, being
utilised to carry IP/MPLS service information such as Layer 3 IP VPN
routes [RFC4364] , and Layer 2 Virtual Private LAN Service device
membership [RFC4761]. Since these extensions to the protocol allow
signalling of multiple services (represented by address families
within BGP), and multiple customer topologies (i.e., subsets of
routes within each address family) via the BGP protocol, the impact
of session failure is increased. The tear down of a single BGP
session can result in a complete outage to all customer services
signalled via the session, even where the triggering event is related
to only one service or topology being carried.
In addition, there has been significant growth in the volume of
routing information carried in BGP. In numerous networks, the RIB
size of individual BGP speakers can be of the order of millions of
paths. Particularly large volumes are observed at BGP speakers
performing aggregation and border roles (such as ASBR, or route
reflector hierarchies). This increased volume of routes results not
only in a significant number of services being impacted during a
protocol failure, but also increases the time to recovery after re-
establishing a BGP session. The time taken to learn, compute and
distribute new paths increases the impact of failures on services
carried by the network - adding further weight to the requirement to
avoid failures, or limit the extent of their impact. Particularly,
the impact of individual session failures is increased due to the
existence of a relatively small number of highly-critical BGP
sessions within Internet and multi-service network deployments.
These sessions propagate a high-proportion of the reachability
information - for instance, providing an Internet AS with the global
routing table from upstream providers, or providing IP/MPLS Provider
Edge devices adjacency with route reflector hierarchy providing
signalling for elements of services connected elsewhere within the
routing domain. In both cases, the failure of these sessions can
result in a significant outage to customer services.
2.2. Service Requirements for Amended BGP Error Handling
Alongside the infrastructure requirements outlined above, service
provider customer requirements continue to evolve. In particular,
there are increasing requirements for robustness and fault isolation
based on:
o The increasing reliance on public IP service instead of private
networks - resulting is requirements for greater availability of
Internet services. The diversity of autonomous systems has
resulted in individual BGP sessions within the Internet carrying
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more routing information (e.g., IP transit, or large peering
interconnections), which is originated from more individual
networks - increasing both the impact of an individual session
failure, and the number of different sources of error which can
lead to its failure. To meet the requirement of high-availability
Internet services, it is therefore an expectation that the error
handling behaviour MUST affect only the those routes, or
autonomous systems, that are are impacted by the erroneous
messages, rather than all routes received by a particular session,
such that the maximum service availability is maintained.
o The requirement to support multiple services. In multi-service
environments such as those that support L3VPNs, multiple customer
VPNs are isolated from one another, and from other IP environments
(such as the Internet). There is an expectation from a service
perspective therefore that the customer service is within its own
fault domain (even when carried via a shared set of signalling),
hence an error on routes or BGP messages related to one VPN SHOULD
NOT negatively impact other VPNs. Further to this, an error
relating to another service (i.e., another address family, such as
Internet or L2VPN services) SHOULD NOT impact the availability of
the VPN service. Both of these principles of fault separation are
required in order to support multiple services and segregated
customer infrastructures over a common network infrastructure
whilst meeting the availability required of them.
It should be noted that the requirements for fault isolation and
high-availability do not imply that routing information that is
potentially erroneous (through being carried in an UPDATE message
that cannot be parsed for example) is always maintained despite
questions as to its integrity, particularly as such routing
information may result in leakage between services - but merely that
there is a requirement to reconsider the balance between protocol
correctness, and robustness.
In addition to these service requirements, an increasing requirement
to minimise the time taken to recover from incidents exists. In some
cases, this may require an operator to compromise on correctness in
order to maintain integrity of a subset of routing information or
services. To meet this requirement, mechanisms allowing an operator
to ignore all errors or maintain "known good" routing information MAY
be required. The implementation of such mechanisms is a business
consideration of the service provider in question, and MUST consider
the balance between the risk of incorrectness and the overall impact
to a network platform. Such mechanisms are particularly of use where
lack of routing information violates an operator's policies (e.g.,
filtering rules distributed via BGP FlowSpec are no longer
installed), or fault isolation requires significant external liaison
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(such as contacting a third-party autonomous system to amend or
filter route announcement).
3. Classes of Errors within UPDATE Messages
To meet the requirement to provide more targeted error handling,
errors are therefore classified into the following scopes:
o Attribute Scope - in this case, an error can be localised to a
particular attribute within the message. For instance, such
errors may occur when invalid flags are set within an individual
attribute within a message, which is otherwise well-formed.
o Message Scope - errors resulting in the inability to parse a
single UPDATE message, but not affecting the ability of an
implementation to parse subsequent BGP messages. For instance,
where the overall length of an UPDATE message is correct, but the
length of a single attribute contained within it is erroneously
specified.
o Session Scope - where errors occur such that an error in an UPDATE
message results in the inability to the parse subsequent messages.
In this case, attribute length errors may result in the inability
for a BGP implementation to locate the bounds of an UPDATE, and
hence the subsequent message from a peer.
For session-scope errors, the error handling approach implemented
MUST conform with the requirements described in Section 5 of this
document (generically referred to as "Critical" error handling
mechanisms). Session-scope errors requiring Critical error handling
MUST be the only case whereby the impact of error handling mechanisms
should be allowed to impact entire BGP sessions between two BGP
speakers.
For message- and attribute-level errors, "Non-Critical" error
handling mechanisms SHOULD be used, which MUST meet the specification
described in Section 4. In the case of attribute-scope errors, a BGP
speaker MUST limit the impact of error-handling mechanisms to the
NLRI carried within the message, and MAY (where applicable) limit to
the scope of error handling to the individual attribute. Where a
message-scope error occurs, a BGP speaker MUST limit the impact of
error handling to the NLRI contained within the affected UPDATE.
3.1. Characteristics of Session Scope Errors
Based on analysis of existing BGP implementations, and incidents
within the Internet and private network routing tables, it is
expected that errors with a session level scope are restricted to:
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o UPDATE Message Length errors - where the specified UPDATE message
length is inconsistent with the sum of the Total Path Attribute
and Withdrawn Routes length. These errors relate to message
packing or framing, and result in cases whereby the NLRI attribute
cannot be correctly extracted from the message.
o Errors parsing the NLRI attribute of an UPDATE message - where the
contents of the IPv4 Unicast Advertised or Withdrawn Routes
attributes, or multi-protocol BGP NLRI attributes (MP_REACH_NLRI
and/or MP_UNREACH_NLRI as defined in [RFC2858]), cannot be
successfully parsed.
3.2. Characteristics of Message Scope Errors
Message scope errors are restricted to those whereby erroneous
encoding results in the ability to parse and determine the NLRI
carried by the message - but the carried attributes are invalid.
These errors (based on existing attributes) are limited to:
o Errors where the length of all path attributes contained within
the UPDATE does not correspond to the total path attribute length.
o UPDATE messages missing mandatory attributes, unrecognised non-
optional attributes, or those that contain duplicate or invalid
attributes (be they unsupported, or unexpected).
o Those messages where the NEXT_HOP, the MP_REACH_NLRI next-hop
values are missing, zero-length, or invalid for the relevant
address family.
3.3. Characteristics of Attribute Scope Errors
Attribute scope errors are defined to be those that relate to an
individual attribute (not related to the NLRI) carried by an UPDATE
message. Particularly, where:
o Zero- or invalid-length errors in path attributes, excluding those
containing NLRI.
o Invalid data or flags are contained in a path attribute that does
not relate to the NLRI.
3.4. Avoiding Session Scope Errors
In order to maximise the number of cases whereby the NLRI attributes
can be reliably extracted from a received message, where a BGP
speaker supports multi-protocol extensions, the MP_REACH_NLRI and
MP_UNREACH_NLRI attributes SHOULD be utilised for all address
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families (including IPv4 Unicast) and these attributes should be the
first attribute contained within the UPDATE message. For these Non-
Critical errors, the NLRI-targeted error handling requirements
described in Section 4 should be followed.
3.5. Future Attributes introduced to BGP
Where attributes are introduced by future extensions to the BGP
protocol error handling behaviour SHOULD be assumed to be be at a
message- or attribute-scope, unless otherwise specified within the
per-extension memo, or the attribute relates directly to carrying
NLRI. It is recommended that authors of future BGP extensions SHOULD
specify the error handling behaviour required on a per-attribute
error basis.
4. Error Handling for Non-Critical Errors
4.1. NLRI-level Error Handling Requirements
When a Non-Critical error is detected within an UPDATE message a BGP
speaker MUST NOT send a NOTIFICATION message to the remote neighbour.
Instead, the NLRI contained within the message SHOULD be considered
as being withdrawn by the neighbour (referred to as treat-as-
withdraw), until they are updated by a subsequent UPDATE message.
Where defined is acceptable by the relevant memo, for the specific-
case of attribute-scope errors, the erroneous attribute MAY be
discarded by an implementation. This attribute-discard approach MUST
only be used for attributes that do not impact best-path selection
within an implementation. An operator SHOULD consider the impact of
implementing policies considering such attributes as part of the
route selection algorithm, such that operator configuration does not
result in unexpected consequences should such an attribute be
discarded.
Network operators SHOULD recognise that where treat-as-withdraw
behaviour is implemented black-holing or looping of traffic may occur
in the period between the NLRI being treated as withdrawn, and
subsequent updates, dependent upon the routing topology. It SHOULD
be noted that such periods of RIB inconsistency (where one speaker
has advertised a prefix, which has had treat-as-withdraw applied to
it by the receiving speaker) may be relatively long lived, based on
situations such as an erroneous implementation at the receiver, or
the error occurring within an optional-transitive attribute not
examined by the direct neighbour. In order to allow operators to
select sessions on which this risk of inconsistency is acceptable, an
implementation SHOULD provide means by which Non-Critical error
handling can be disabled on a per-session basis.
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Since the Non-Critical error handling required within this section
results in no NOTIFICATION message being transmitted, the fact that
an error has occurred, and there may be inconsistency between the
local and remote BGP speaker MUST be flagged to the network operator
through standard operational interfaces (e.g., SNMP, syslog). The
information highlighted MUST include the NLRI identified to be
contained within the error message, and SHOULD contain a exact copy
of the received message for further analysis.
4.1.1. Notifying the Remote Peer of Non-Critical Errors
In order that the operator of the BGP speaker from whom an erroneous
UPDATE message has been advertised is aware of the fact that some
NLRI advertised to the remote speaker have been considered invalid, a
BGP speaker SHOULD support mechanisms to report the occurrence of
Non-Critical error handling to the remote speaker. The receiving
speaker SHOULD transmit the NLRI contained within the erroneous
message to the advertising speaker. An exact copy of the received
UPDATE message SHOULD also be sent.
The exchange of such information related to events occurring as a
result of BGP messages is not currently supported by any extension to
the protocol. Clearly, where the two speakers reside within the same
administrative domain, shared logging information can be utilised to
identify the root cause of errors. However, in many cases these
devices reside within separate administrative domains (e.g., are
ASBRs for Internet or private networks). In this case, mechanisms
allowing transmission in-band to the BGP session SHOULD be utilised
(e.g., the OPERATIONAL message described in
[I-D.ietf-idr-operational-message]). Such an in-band channel is
preferred based on the BGP session representing a pre-established
trusted source which is related to a specific BGP-speaking device
within a network. It is expected that the overall system scalability
of a BGP speaker is improved through utilising the existing channel,
rather than incurring overhead for maintaining many additional
sessions for relatively infrequent messaging events when errors
occur. However, the extensions providing such a channel MUST
consider their impact to base BGP protocol functions such as the
transmission of UPDATE or KEEPALIVE messages, and SHOULD limit the
volume of messaging to direct reactions to Non-Critical errors
occurring. These considerations SHOULD be made in order to ensure
that no compromise is made to the security, scalability and
robustness of BGP. Where additional BGP monitoring information that
is not suitable to be carried in-band is required, out-of-band
mechanisms such as the BMP protocol described in [I-D.ietf-grow-bmp]
could be utilised to provide further information relating to
erroneous messages.
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4.2. Recovering RIB Consistency following NLRI-level Error Handling
In order to recover consistency of Adj-RIBs following Non-Critical
error handling, a means by which a validation and recovery of
consistency can be achieved SHOULD be provided to an operator. This
functionality MAY be provided through extension of the ROUTE-REFRESH
[RFC2918] mechanism - providing means to identify the beginning and
end of a replay of the entire Adj-RIB-Out of the advertising speaker
(as per the suggestion in [I-D.ietf-idr-bgp-enhanced-route-refresh]).
As Non-Critical error handling is localised to the NLRI contained
within the erroneous UPDATE message, a targeted recovery mechanism
MAY be provided allowing a speaker to request re-advertisement of a
particular subset of the Adj-RIB-Out. Where such targeted refresh
functions are available, they SHOULD be preferred to mechanisms
requesting re-advertisement of the whole Adj-RIB-Out based on their
more limited use of CPU and network resources.
A BGP speaker may automatically trigger recovery mechanisms such as
those described in this section following the receipt of an erroneous
UPDATE message identified as Non-Critical to expedite recovery. It
SHOULD be noted that if automatic recovery mechanisms trigger only
re-advertisement of an identical erroneous message, they may be
ineffective. Additionally, where the best-path to be advertised by
remote speaker changes, this will be advertised directly, without a
requirement for a request from the receiver. However, in some cases,
RIB consistency recovery mechanisms may prompt alternate UPDATE
message packing, and hence allow quicker recovery. Where such
automatic mechanisms are implemented, those focused on smaller sets
of NLRI SHOULD be preferred over those requesting the entire RIB. In
addition, such mechanisms SHOULD have dampening mechanisms to ensure
that their impact to computational and network resources is limited.
5. Error Handling for Critical Errors
Critical error handling MUST be used where session-scope errors
occur. In such cases, a NOTIFICATION message MUST be sent to the
remote peer. In order to limit the impact to network operation,
during such events the mechanisms applied MUST allow for the paths
NLRI received from the remote speaker to continue to be utilised
during the session reset and re-establishment. It is envisaged that
this requirement may be met through extension of the BGP Graceful
Restart mechanism ([RFC4724]) to be triggered by NOTIFICATION
messages indicating the occurrence of a Critical error. Such an
extension allows a restart of the TCP and BGP sessions between two
speakers, in a similar manner to the current session restart
behaviour triggered by a NOTIFICATION message. In order to maximise
the level of re-initialisation which occurs during such a restart
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triggered by a Critical error, BGP speakers MAY re-initialise memory
structures related to the RIB where possible.
Where such a restart event occurs, the continued liveliness of the
remote device MAY be verified by BGP KEEPALIVE packets or other OAM
functions such as Bidirectional Forwarding Detection ([RFC5880]). If
the observed Critical BGP error is indicative of a wider device
failure of the remote speaker, it is expected that a BGP sessions
will not re-establish correctly. By default, each BGP speaker SHOULD
maintain a limited time window in which session restart is expected
in order to mitigate this possibility.
When a Critical error occurs, the network operator MUST be made aware
of its occurrence through local logging mechanisms (e.g., SNMP traps
or syslog). The BGP speaker receiving an UPDATE message identified
as a Critical error MUST log its occurrence and a copy of the UPDATE
message. Where a inter-device messaging mechanism is implemented (as
discussed in Section Section 4.1) a copy of the erroneous UPDATE
message SHOULD be transmitted to the remote speaker upon session-re-
establishment (or via a separate session if implemented). Both BGP
speakers MUST indicate to an operator the cause of a session restart
was a Critical error in an UPDATE message.
Since repeated critical errors (and session restarts) may have an
impact in overall device scaling if Critical error handling does not
resolve the failure condition, a BGP speaker MAY choose to revert to
the session tear down behaviour described in the base BGP
specification. This reversion SHOULD only be utilised after a number
of attempts which MUST be controllable by the network operator.
Where a session is shut down, the implementation MAY utilise a back-
off from session restart attempts (as per the IdleHoldTimer described
in the BGP FSM [RFC4271]). Where reversion to tearing down the BGP
session is performed, a speaker SHOULD limit the impact of
withdrawing prefixes from downstream speakers where possible. It is
envisaged that this can be achieved by utilising a mechanism such as
the BGP Graceful Shutdown procedure as described in
[I-D.ietf-grow-bgp-gshut].
5.1. Long-Lived Critical Errors
Where Critical error handling mechanisms are required to be utilised,
significant impact to an operator's network or services may still be
experienced. In order to allow an operator to avoid such scenarios:
o An implementation MAY provide functionality whereby all future
Critical errors result in UPDATE messages being discarded. Such
functionality MUST be disabled by default, and SHOULD be
configurable on a per-address-family basis. An operator MUST
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consider such mechanisms as a tool of last-resort to maintain
service for a subset of NLRI, whilst the root cause of a such
errors is investigated and resolved. This MAY be achieved by
filtering erroneous NLRI at an upstream peer.
o Provide means by which a the restart timer for Graceful Restart
can be configured to be a long period (order of days, or weeks)
such that a critical failure can be resolved whilst maintaining
operation for a subset of NLRI. This restart period MUST be
configured separately to standard graceful-restart timers and MUST
be configurable per-address-family. Long-lived restart mechanisms
MAY be configurable to be utilised by default. An operator MUST
configure the impact to forwarding correctness of such
configuration, based on the expected rate of change of NLRI within
a particular <AFI,SAFI>.
6. IANA Considerations
This memo includes no request to IANA.
7. Security Considerations
The requirements outlined in this document provide mechanisms which
limit the forwarding impact of the response to an error in a BGP
UPDATE message. This is of benefit to the security of a BGP speaker.
Without these mechanisms, where erroneous UPDATE messages relating to
a single NLRI entry can be propagated to a BGP speaker, all other
NLRI carried via the same session are affected by the resulting
session tear-down. This may result in a means by which an AS can be
isolated from particular routing domains (such as the Internet)
should an UPDATE message be propagated via targeted specific paths.
It is envisaged by reducing the impact of the reaction of the
receiving speaker to these messages, the isolation can be constrained
to specific sets of NLRI, or a specific topology.
A number of the mechanisms meeting the requirements specified within
the document (particularly those relating to operational monitoring)
may raise further security concerns. Such concerns will be addressed
during the specification of these mechanisms.
8. Acknowledgements
Many thanks are extended to Bruno Decraene and David Freedman for
their numerous detailed reviews, and significant contribution towards
the refinement of the requirements in this document.
In addition, the author would like to thank the following network
operators for their insight, and valuable input into defining the
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requirements for a variety of deployments of BGP: Shane Amante, Colin
Bookham, Rob Evans, Wes George, Tom Hodgson, Sven Huster, Jonathan
Newton, Neil McRae, Thomas Mangin, Tom Scholl and Ilya Varlashkin.
Many thanks are extended to Jeff Haas, Wim Hendrickx, Tony Li, Alton
Lo, Keyur Patel, John Scudder, Adam Simpson and Robert Raszuk for
their expertise relating to implementations of the BGP protocol.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2858] Bates, T., Rekhter, Y., Chandra, R., and D. Katz,
"Multiprotocol Extensions for BGP-4", RFC 2858, June 2000.
[RFC2918] Chen, E., "Route Refresh Capability for BGP-4", RFC 2918,
September 2000.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
[RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
January 2007.
[RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service
(VPLS) Using BGP for Auto-Discovery and Signaling", RFC
4761, January 2007.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, June 2010.
9.2. Informational References
[I-D.chen-ebgp-error-handling]
Chen, E., Mohapatra, P., and K. Patel, "Revised Error
Handling for BGP Updates from External Neighbors", draft-
chen-ebgp-error-handling-01 (work in progress), September
2011.
Shakir Expires May 13, 2015 [Page 13]
Internet-Draft Requirements for BGP Error Handling November 2014
[I-D.ietf-grow-bgp-gshut]
Francois, P., Decraene, B., Pelsser, C., Patel, K., and C.
Filsfils, "Graceful BGP session shutdown", draft-ietf-
grow-bgp-gshut-06 (work in progress), August 2014.
[I-D.ietf-grow-bmp]
Scudder, J., Fernando, R., and S. Stuart, "BGP Monitoring
Protocol", draft-ietf-grow-bmp-07 (work in progress),
October 2012.
[I-D.ietf-idr-bgp-enhanced-route-refresh]
Patel, K., Chen, E., and B. Venkatachalapathy, "Enhanced
Route Refresh Capability for BGP-4", draft-ietf-idr-bgp-
enhanced-route-refresh-10 (work in progress), June 2014.
[I-D.ietf-idr-operational-message]
Freedman, D., Raszuk, R., and R. Shakir, "BGP OPERATIONAL
Message", draft-ietf-idr-operational-message-00 (work in
progress), March 2012.
Author's Address
Rob Shakir
BT plc.
pp. C3L,
BT Centre,
81, Newgate Street,
London. EC1A 7AJ
UK
Email: rob.shakir@bt.com
URI: http://www.bt.com/
Shakir Expires May 13, 2015 [Page 14]
