draft-ietf-idr-bgp-autoconf-considerations-00.txt   draft-ietf-idr-bgp-autoconf-considerations-01.txt 
Network Working Group R. Bush Network Working Group R. Bush
Internet-Draft Arrcus, Inc. & Internet Initiative Japan Internet-Draft Arrcus, Inc. & Internet Initiative Japan
Intended status: Informational J. Dong Intended status: Informational J. Dong
Expires: September 9, 2021 Huawei Technologies Expires: 27 December 2021 Huawei Technologies
J. Haas, Ed. J. Haas, Ed.
Juniper Networks Juniper Networks
W. Kumari, Ed. W. Kumari, Ed.
Google Google
March 8, 2021 25 June 2021
Requirements and Considerations in BGP Peer Auto-Configuration Requirements and Considerations in BGP Peer Auto-Configuration
draft-ietf-idr-bgp-autoconf-considerations-00 draft-ietf-idr-bgp-autoconf-considerations-01
Abstract Abstract
This draft is an exploration of the requirements, the alternatives, This draft is an exploration of the requirements, the alternatives,
and trade-offs in BGP peer auto-discovery at various layers in the and trade-offs in BGP peer auto-discovery at various layers in the
stack. It is based on discussions in the IDR Working Group BGP stack. It is based on discussions in the IDR Working Group BGP
Autoconf Design Team. The current target environment is the Autoconf Design Team. The current target environment is the
datacenter. datacenter.
This document is not intended to become an RFC. This document is not intended to become an RFC.
skipping to change at page 1, line 49 skipping to change at page 1, line 49
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 September 9, 2021. This Internet-Draft will expire on 27 December 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Design Team Determinations . . . . . . . . . . . . . . . . . 3 2. Design Team Determinations . . . . . . . . . . . . . . . . . 3
2.1. Problem Scope . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Problem Scope . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Simplicity . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Simplicity . . . . . . . . . . . . . . . . . . . . . . . 3
2.3. BGP Auto-Discovery Protocol State Requirements . . . . . 3 2.3. BGP Auto-Discovery Protocol State Requirements . . . . . 3
2.3.1. BGP Session Transport State . . . . . . . . . . . . . 4 2.3.1. BGP Auto-Discovery Protocol State . . . . . . . . . . 4
2.3.2. BGP Session Protocol State . . . . . . . . . . . . . 4 2.3.2. BGP Session Protocol State . . . . . . . . . . . . . 4
2.4. BGP Auto-Discovery Protocol Transport Requirements . . . 5 2.4. BGP Auto-Discovery Protocol Transport Requirements . . . 4
2.5. Operator Configuration . . . . . . . . . . . . . . . . . 5 2.5. Operator Configuration . . . . . . . . . . . . . . . . . 5
3. Design Principle Considerations . . . . . . . . . . . . . . . 6 3. Design Principle Considerations . . . . . . . . . . . . . . . 5
3.1. Transport Considerations . . . . . . . . . . . . . . . . 6 3.1. Transport Considerations . . . . . . . . . . . . . . . . 5
3.2. Auto-Discovery Protocol Timing Considerations . . . . . . 6 3.2. Auto-Discovery Protocol Timing Considerations . . . . . . 6
3.3. Relationship with BGP . . . . . . . . . . . . . . . . . . 7 3.3. Relationship with BGP . . . . . . . . . . . . . . . . . . 6
3.4. Session Selection Considerations . . . . . . . . . . . . 7 3.4. Session Selection Considerations . . . . . . . . . . . . 6
3.5. Operational Trust Considerations . . . . . . . . . . . . 7 3.5. Session Stability Considerations . . . . . . . . . . . . 7
3.6. Error Handling Considerations . . . . . . . . . . . . . . 9 3.6. Operational Trust Considerations . . . . . . . . . . . . 7
3.7. Error Handling Considerations . . . . . . . . . . . . . . 9
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
5.1. BGP Transport Security Considerations . . . . . . . . . . 10 5.1. BGP Transport Security Considerations . . . . . . . . . . 10
5.2. Auto-discovery Protocol Considerations . . . . . . . . . 10 5.2. Auto-discovery Protocol Considerations . . . . . . . . . 10
5.2.1. Potential Scopes of an Auto-discovery Protocol . . . 10 5.2.1. Potential Scopes of an Auto-discovery Protocol . . . 10
5.2.2. Desired Security Properties of the Auto-discovery 5.2.2. Desired Security Properties of the Auto-discovery
Protocols . . . . . . . . . . . . . . . . . . . . . . 11 Protocols . . . . . . . . . . . . . . . . . . . . . . 11
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . 12 7.1. Normative References . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . 12 7.2. Informative References . . . . . . . . . . . . . . . . . 12
Appendix A. Analysis of Candidate Approaches . . . . . . . . . . 14 Appendix A. Analysis of Candidate Approaches . . . . . . . . . . 14
A.1. BGP Peer Discovery at Layer Two . . . . . . . . . . . . . 14 A.1. BGP Peer Discovery at Layer Two . . . . . . . . . . . . . 14
A.1.1. LLDP based Approach . . . . . . . . . . . . . . . . . 14 A.1.1. LLDP based Approach . . . . . . . . . . . . . . . . . 15
A.1.2. L3DL based Approach . . . . . . . . . . . . . . . . . 15 A.1.2. L3DL based Approach . . . . . . . . . . . . . . . . . 15
A.2. Link-Local Discovery . . . . . . . . . . . . . . . . . . 15 A.2. Link-Local Discovery . . . . . . . . . . . . . . . . . . 16
A.3. BGP peer Discovery at Layer Three . . . . . . . . . . . . 16 A.3. BGP peer Discovery at Layer Three . . . . . . . . . . . . 16
A.3.1. New BGP Hello Message based Approach . . . . . . . . 16 A.3.1. New BGP Hello Message based Approach . . . . . . . . 17
A.3.2. BGP OPEN Message based Approach . . . . . . . . . . . 17 A.3.2. BGP OPEN Message based Approach . . . . . . . . . . . 17
A.3.3. Bootstrapping BGP via BGP . . . . . . . . . . . . . . 17 A.3.3. Bootstrapping BGP via BGP . . . . . . . . . . . . . . 18
A.3.4. Bootstrapping BGP via OSPF . . . . . . . . . . . . . 18 A.3.4. Bootstrapping BGP via OSPF . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
This draft is an exploration of the requirements, the alternatives, This draft is an exploration of the requirements, the alternatives,
and trade-offs in BGP peer auto-discovery at various layers in the and trade-offs in BGP peer auto-discovery at various layers in the
stack. It is based on discussions in the IDR Working Group BGP stack. It is based on discussions in the IDR Working Group BGP
Autoconf Design Team. The current target environment is the Autoconf Design Team. The current target environment is the
datacenter. datacenter.
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The auto-discovery mechanism is designed to be simple. The auto-discovery mechanism is designed to be simple.
The goal is to select BGP Speakers where a BGP session may be The goal is to select BGP Speakers where a BGP session may be
successfully negotiated for a particular purpose. The auto-discovery successfully negotiated for a particular purpose. The auto-discovery
mechanism will not replace or conflict with data exchanged by the BGP mechanism will not replace or conflict with data exchanged by the BGP
FSM, including its OPEN message. FSM, including its OPEN message.
2.3. BGP Auto-Discovery Protocol State Requirements 2.3. BGP Auto-Discovery Protocol State Requirements
Tersely, the required state that MUST be carried by the BGP Auto- The Auto-Discovery Protocol is used discover BGP Session end-points.
Discovery Protocol for a discovered session include: In other words, enough information to for a BGP Speaker to initiate a
connection in the BGP protocol.
BGP Session Transport State: The BGP Session Properties, used by the discovering client to
determine acceptability of the discovered session, are "discovered at
OPEN" by the client by initiating a BGP session with the discovered
end-point.
o IP addresses The required state that MUST be carried by the BGP Auto-Discovery
o Transport security parameters Protocol for a discovered session includes:
o GTSM [RFC5082] configuration, if any
o BFD [RFC5880] configuration, if any
BGP Session Protocol State: * IP addresses
* Transport security parameters
* GTSM [RFC5082] configuration, if any
* BGP Session Protocol State Version Number
o AS Numbers BGP Session Protocol State, discovered at BGP OPEN:
o BGP Identifier
o Supported AFI/SAFIs
o Device Role
Once this information has been learned, discovery has been completed. * AS Numbers
The BGP Speaker has the necessary information to determine if it * BGP Identifier
wishes to open a BGP session with the discovered BGP Speaker. It can * Supported AFI/SAFIs
then then initiate a BGP session with the discovered BGP Speaker.
2.3.1. BGP Session Transport State 2.3.1. BGP Auto-Discovery Protocol State
o Support for IPv4 and IPv6 address families, but do not assume that * Support for IPv4 and IPv6 address families, but do not assume that
both are available. both are available.
o The ability to use directly attached interface addresses, or the * The ability to use directly attached interface addresses, or the
device's Loopback address. When using the Loopback address, device's Loopback address. When using the Loopback address,
potentially exchange additional information to bootstrap potentially exchange additional information to bootstrap
forwarding to that address. forwarding to that address.
o Discovery of BGP transport protocol end-points and essential * Discovery of BGP transport protocol end-points and essential
properties such as IP addresses, transport security parameters, properties such as IP addresses, transport security parameters,
layer 3 liveness mechanisms such as BFD, and support for GTSM. and support for GTSM.
o Transport security parameters include protocol - such as plain * Transport security parameters include protocol - such as plain
TCP, TCP-AO [RFC5925], IPsec [RFC4301], TCP-MD5 [RFC2385] - and TCP, TCP-AO [RFC5925], IPsec [RFC4301], TCP-MD5 [RFC2385] - and
necessary configuration for that protocol. Some example necessary configuration for that protocol. Some example
considerations for this are represented in YANG Data Model for Key considerations for this are represented in YANG Data Model for Key
Chains [RFC8177]. Chains [RFC8177].
* A version number representing when the BGP Session Protocol State
has last changed. This can be used as a hint by an auto-discovery
client to determine when the state has been updated from a prior
version. This can reduce repeated connections from an auto-
discovery client to the discovered BGP Speaker when information
has not changed.
2.3.2. BGP Session Protocol State 2.3.2. BGP Session Protocol State
o Discovery of BGP peer session parameters relevant to peer * Discovery of BGP peer session parameters relevant to peer
selection such as Autonomous System (AS) Numbers, BGP Identifiers, selection such as Autonomous System (AS) Numbers, BGP Identifiers,
supported address families/subsequent-address families (AFI/ supported address families/subsequent-address families (AFI/
SAFIs), and device roles. SAFIs).
2.3.2.1. BGP Auto-Discovery Device Role Requirements
As part of peer selection, it may be necessary to understand the role
of the discovered session to determine whether or not the BGP Speaker
desires to establish a peering session.
In some cases, role may be a clear function of the device in a
deployment. An example of this is a discovered session for a BGP
Clos fabric: The interface may for a leaf, the aggregation layer, or
the spine layer. Even then, the type of fabric, what pod it belongs
to and the peer type may be relevant information.
Some types of device roles may be subject to standardization, such as
BGP Clos fabrics. Flexibility to permit operators to use device
roles for their own auto-configuration peer selection purposes is a
requirement.
Peering sessions may need to advertise that they are capable to be
used for multiple roles. Thus, it is a requirement that the auto-
discovery protocols permit advertising multiple roles in the same
PDU.
2.4. BGP Auto-Discovery Protocol Transport Requirements 2.4. BGP Auto-Discovery Protocol Transport Requirements
BGP Auto-Discovery Protocol State may be carried in multiple BGP Auto-Discovery Protocol State may be carried in multiple
protocols operating in different transport layers. protocols operating in different transport layers.
Implementations supporting more than one protocol for this state must Implementations supporting more than one protocol for this state must
have a mechanism for consistently selecting discovered BGP sessions. have a mechanism for consistently selecting discovered BGP sessions.
The BGP Identifier, which is carried by the BGP OPEN message, can The BGP Identifier, which is carried by the BGP OPEN message, can
help detect sessions to the same BGP Speaker carried in multiple help detect sessions to the same BGP Speaker carried in multiple
protocols. protocols.
2.5. Operator Configuration 2.5. Operator Configuration
With BGP auto-discovery, some configuration of BGP is still needed. With BGP auto-discovery, some configuration of BGP is still needed.
Operator configuration should be able to decide at least the Operator configuration should be able to decide at least the
following: following:
o Select or otherwise filter which peers to actually try to send BGP * Select or otherwise filter which peers to actually try to send BGP
OPEN messages. OPEN messages.
* Decide the parameters to use. For example:
* Permit the matching of device role from the discovery protocol - IP addressing: IPv4 or IPv6.
as part of peer selection. - Interface for peering: Loopback, or Direct.
o Decide the parameters to use. For example: - Any special forwarding or routing needed for reaching the
* IP addressing: IPv4 or IPv6.
* Interface for peering: Loopback, or Direct.
* Any special forwarding or routing needed for reaching the
prospective peer; for example, loopback. prospective peer; for example, loopback.
* AS numbering. - AS numbering.
* BGP Transport Security Parameters. - BGP Transport Security Parameters.
* BGP Policy that is appropriate for the type of discovered - BGP Policy that is appropriate for the type of discovered
session. session.
In addition to actually forming the BGP sessions, a common deployment In addition to actually forming the BGP sessions, a common deployment
model may also be the so called "validation" model. In this model, model may also be the so called "validation" model. In this model,
the operator configures the BGP sessions manually, and uses the the operator configures the BGP sessions manually, and uses the
information collected/populated by the BGP Autoconf mechanism to information collected/populated by the BGP Auto-Configuration
validate that the sessions are correct. mechanism to validate that the sessions are correct.
3. Design Principle Considerations 3. Design Principle Considerations
This section summarizes the considerations of possible criteria for This section summarizes the considerations of possible criteria for
the design of a BGP auto-discovery mechanism, which may need further the design of a BGP auto-discovery mechanism, which may need further
discussion in a wider community than the design team; for example, discussion in a wider community than the design team; for example,
the IDR Working Group. the IDR Working Group.
3.1. Transport Considerations 3.1. Transport Considerations
The network layer of the discovery mechanism may impact the scoping The network layer of the discovery mechanism may impact the scoping
of the deployment of the auto-discovery mechanism. of the deployment of the auto-discovery mechanism.
o Layer 2: For example, based on Ethernet. * Layer 2: For example, based on Ethernet.
o Layer 3: Which is generic for any link-layer protocol. * Layer 3: Which is generic for any link-layer protocol.
Potentially leveraging existing protocols deployed in the data Potentially leveraging existing protocols deployed in the data
center. center.
The length of messages supported by the protocol. The length of messages supported by the protocol.
How extensible the protocol is to carry future state for BGP auto- How extensible the protocol is to carry future state for BGP auto-
configuration. configuration.
3.2. Auto-Discovery Protocol Timing Considerations 3.2. Auto-Discovery Protocol Timing Considerations
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Establishing a reasonable expectation for the timeliness of auto- Establishing a reasonable expectation for the timeliness of auto-
configuration is desirable. When a link is plugged-in, one shouldn't configuration is desirable. When a link is plugged-in, one shouldn't
have to wait minutes for potential peers to be discovered and BGP have to wait minutes for potential peers to be discovered and BGP
session establishment attempted. For protocols crafted explicitly session establishment attempted. For protocols crafted explicitly
for BGP auto-configuration, the time for discovery should be a for BGP auto-configuration, the time for discovery should be a
reasonable amount of time; for example ten seconds or less. reasonable amount of time; for example ten seconds or less.
Since discovery mechanisms may become very chatty when utilized by a Since discovery mechanisms may become very chatty when utilized by a
number of devices on shared networks, the protocol should not impose number of devices on shared networks, the protocol should not impose
undue burden on the devices on that network to process the discovery undue burden on the devices on that network to process the discovery
messages. New auto-discovery protcols MUST NOT transmit messages messages. New auto-discovery protocols MUST NOT transmit messages
more than once a second. more than once a second.
When an auto-discovery mechanism is used for a point-to-point link, When an auto-discovery mechanism is used for a point-to-point link,
or with the expectation of establishing a BGP session with a single or with the expectation of establishing a BGP session with a single
BGP Speaker on that network, the auto-discovery protocol MAY quiesce BGP Speaker on that network, the auto-discovery protocol MAY quiesce
once the discovered BGP session has become Established. once the discovered BGP session has become Established.
In cases where the auto-discovery protocol is carried as state in In cases where the auto-discovery protocol is carried as state in
another protocol, that protocol will have its own timeliness another protocol, that protocol will have its own timeliness
considerations. The auto-discovery mechanism SHOULD NOT interfere considerations. The auto-discovery mechanism SHOULD NOT interfere
with the timing of the existing protocol. with the timing of the existing protocol.
3.3. Relationship with BGP 3.3. Relationship with BGP
o The auto-discovery mechanism should be independent from BGP * The auto-discovery mechanism should be independent from BGP
session establishment. session establishment.
o Not affect on BGP session establishment and routing exchange, * Not affect on BGP session establishment and routing exchange,
other than the interactions for triggering the setup/removal of other than the interactions for triggering the setup/removal of
peer sessions based on the discovery mechanism. peer sessions based on the discovery mechanism.
o Potentially leveraging existing BGP protocol sessions for * Potentially leveraging existing BGP protocol sessions for
discovery of new BGP sessions. discovery of new BGP sessions.
3.4. Session Selection Considerations 3.4. Session Selection Considerations
Candidate BGP sessions to a given BGP Speaker may be discovered by Candidate BGP sessions to a given BGP Speaker may be discovered by
one or more auto-discovery protocols. Even for a single protocol, one or more auto-discovery protocols. Even for a single protocol,
multiple transport session endpoints may be discovered for the same multiple transport session endpoints may be discovered for the same
BGP Speaker. These different sessions may be required for supporting BGP Speaker. These different sessions may be required for supporting
different address families, such as IPv4/IPv6, depending on the BGP different address families, such as IPv4/IPv6, depending on the BGP
operational practices for that device. Examples include a distinct operational practices for that device. Examples include a distinct
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can serve to identify the same instance of the BGP Speaker. This is can serve to identify the same instance of the BGP Speaker. This is
a required element of the information to be carried in the auto- a required element of the information to be carried in the auto-
discovery protocol. discovery protocol.
When multiple mechanisms exist to discovery the same BGP speaker in When multiple mechanisms exist to discovery the same BGP speaker in
an implementation, that implementation MUST document the process by an implementation, that implementation MUST document the process by
which it chooses discovered peers. Those implementations also MUST which it chooses discovered peers. Those implementations also MUST
describe interactions with their protocol state machinery for each describe interactions with their protocol state machinery for each
mechanism. mechanism.
3.5. Operational Trust Considerations 3.5. Session Stability Considerations
BFD [RFC5880] is often used to provide fast failure detection for the
BGP protocol. To provide for maximum compatibility and ease of use
for auto-discovered sessions, [I-D.ietf-idr-bgp-bfd-strict-mode]
SHOULD be used to provide consistent BFD protection for an auto-
discovered BGP session.
3.6. Operational Trust Considerations
Different deployment models will have different trust models and Different deployment models will have different trust models and
requirements. Some of this will be driven by the size, complexity requirements. Some of this will be driven by the size, complexity
and operational practices of the operator. For example, some and operational practices of the operator. For example, some
operators have very strict physical protection of the datacenter, and operators have very strict physical protection of the datacenter, and
their deployment model assumes that anything which plugs into devices their deployment model assumes that anything which plugs into devices
in the datacenter is, by definition, trusted. Other operators take a in the datacenter is, by definition, trusted. Other operators take a
very different approach, and assume the least possible amount of very different approach, and assume the least possible amount of
trust. trust.
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validation of the datacenter fabric, and ongoing "sanity-checking" to validation of the datacenter fabric, and ongoing "sanity-checking" to
confirm that the datacenter is correctly cabled, and that the BGP confirm that the datacenter is correctly cabled, and that the BGP
sessions which have been configured from the database match what the sessions which have been configured from the database match what the
autodiscovered sessions would have created. Over time, if the BGP autodiscovered sessions would have created. Over time, if the BGP
Autoconf solution proves to be successful, reliable, and scaleable, Autoconf solution proves to be successful, reliable, and scaleable,
operators may begin using it as the primary source of record. operators may begin using it as the primary source of record.
Closely related to these considerations is the "scope" of the Closely related to these considerations is the "scope" of the
discovery process. It is expected that many operators will wish to discovery process. It is expected that many operators will wish to
only perform discovery on "infrastructure" or "fabric" interfaces, only perform discovery on "infrastructure" or "fabric" interfaces,
and not interfaces which face customers. and not interfaces to customers.
It is not clear that the solution that chosen will be able to meet It is not clear that the solution that chosen will be able to meet
all of the trust and deployment models, and we will need to all of the trust and deployment models, and we will need to
prioritize which set(s) of deployment scenarios are the most prioritize which set(s) of deployment scenarios are the most
important for the Working Group to solve. important for the Working Group to solve.
Trust/Operational deployment driven requirements. The solution Trust/Operational deployment driven requirements. The solution
should: should:
o Allow operators to determine which classes of interfaces the * Allow operators to determine which classes of interfaces the
discovery protocol operates on (e.g: "Interfaces numbered 1-17" or discovery protocol operates on (e.g: "Interfaces numbered 1-17" or
"Only 100GE interfaces"). This is likely an implementation "Only 100GE interfaces"). This is likely an implementation
detail. detail.
o Allow operation in a "validation" or "verification" only mode, * Allow operation in a "validation" or "verification" only mode,
where the Autoconf solution populates a database or model showing where the Autoconf solution populates a database or model showing
what sessions it would bring up if allowed. what sessions it would bring up if allowed.
o Ideally allow for different levels of "granularity" in pre-
* Ideally allow for different levels of "granularity" in pre-
configuration. For example, if the protocol is capable of configuration. For example, if the protocol is capable of
autoconfiguring everything, it should also support filtering or autoconfiguring everything, it should also support filtering or
limiting the session according to configured policy. (Likely an limiting the session according to configured policy. (Likely an
implementation detail.) implementation detail.)
* Support preconfigured authentication systems. This is an area
o Support preconfigured authentication systems. This is an area
where more discussion is needed! The solution MUST also support a where more discussion is needed! The solution MUST also support a
"no authentication" mode. Negotiated keying solutions, such as "no authentication" mode. Negotiated keying solutions, such as
IKE, may be desireable but not mandatory for the solution. IKE, may be desireable but not mandatory for the solution.
o Support Ethernet sub-interfaces such as VLANs. * Support Ethernet sub-interfaces such as VLANs.
o Support non-Ethernet interfaces. This may include tunnels. * Support non-Ethernet interfaces. This may include tunnels.
3.6. Error Handling Considerations 3.7. Error Handling Considerations
The purpose of the BGP auto-discovery protocol is to discover The purpose of the BGP auto-discovery protocol is to discover
potential BGP sessions and provide enough information for a BGP potential BGP sessions and provide enough information for a BGP
Speaker to start a BGP session. It is possible for the information Speaker to start a BGP session. It is possible for the information
present in the auto-discovery protocol to not match the session's present in the auto-discovery protocol to not match the session's
information. Such mis-matches will result in different classes of information. Such mis-matches will result in different classes of
problems: problems:
o The BGP transport session may not connect. This could be the * The BGP transport session may not connect. This could be the
result of mismatches in IP addresses, GTSM configuration, BGP result of mismatches in IP addresses, GTSM configuration, BGP
transport security configuration, etc. In these cases, a BGP transport security configuration, etc. In these cases, a BGP
Speaker attempts to establish a session and fails. Speaker attempts to establish a session and fails.
Implementations SHOULD provide a way to clear such discovered Implementations SHOULD provide a way to clear such discovered
sessions or exclude them from further connect attempts. sessions or exclude them from further connect attempts.
o The BGP transport session connects, but the parameters in the BGP * The BGP transport session connects, but the parameters in the BGP
OPEN message do not match those in the auto-discovery protocol. OPEN message do not match those in the auto-discovery protocol.
In this case, the implementation may wish to disconnect from the In this case, the implementation may wish to disconnect from the
BGP session and exclude it from further connection attempts. The BGP session and exclude it from further connection attempts. The
implementation SHOULD raise a visible fault to the operator. The implementation SHOULD raise a visible fault to the operator. The
implementation SHOULD provide a mechanism to permit further implementation SHOULD provide a mechanism to permit further
attempts to connect to the discovered session. attempts to connect to the discovered session.
o The operator may choose to leverage the auto-discovery mode for * The operator may choose to leverage the auto-discovery mode for
validation purposes only. The implementation should provide validation purposes only. The implementation should provide
access to the operator for discovered BGP sessions from the auto- access to the operator for discovered BGP sessions from the auto-
discovery protocol; for example via the user-interface. The discovery protocol; for example via the user-interface. The
implementation SHOULD permit a manually configured BGP session to implementation SHOULD permit a manually configured BGP session to
conflict with information present in the auto-discovery protocol, conflict with information present in the auto-discovery protocol,
but SHOULD raise an alarm with the operator that this has been but SHOULD raise an alarm with the operator that this has been
done. done.
4. IANA Considerations 4. IANA Considerations
skipping to change at page 12, line 23 skipping to change at page 12, line 27
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
7.2. Informative References 7.2. Informative References
[I-D.acee-idr-lldp-peer-discovery] [I-D.acee-idr-lldp-peer-discovery]
Lindem, A., Patel, K., Zandi, S., Haas, J., and X. Xu, Lindem, A., Patel, K., Zandi, S., Haas, J., and X. Xu,
"BGP Logical Link Discovery Protocol (LLDP) Peer "BGP Logical Link Discovery Protocol (LLDP) Peer
Discovery", draft-acee-idr-lldp-peer-discovery-08 (work in Discovery", Work in Progress, Internet-Draft, draft-acee-
progress), December 2020. idr-lldp-peer-discovery-08, 7 December 2020,
<https://www.ietf.org/archive/id/draft-acee-idr-lldp-peer-
discovery-08.txt>.
[I-D.acee-ospf-bgp-rr] [I-D.acee-ospf-bgp-rr]
Lindem, A., Patel, K., Zandi, S., and R. Raszuk, "OSPF Lindem, A., Patel, K., Zandi, S., and R. Raszuk, "OSPF
Extensions for Advertising/Signaling BGP Route Reflector Extensions for Advertising/Signaling BGP Route Reflector
Information", draft-acee-ospf-bgp-rr-01 (work in Information", Work in Progress, Internet-Draft, draft-
progress), September 2017. acee-ospf-bgp-rr-01, 7 September 2017,
<https://www.ietf.org/archive/id/draft-acee-ospf-bgp-rr-
01.txt>.
[I-D.ietf-idr-bgp-bfd-strict-mode]
Zheng, M., Lindem, A., Haas, J., and A. Fu, "BGP BFD
Strict-Mode", Work in Progress, Internet-Draft, draft-
ietf-idr-bgp-bfd-strict-mode-05, 25 April 2021,
<https://www.ietf.org/archive/id/draft-ietf-idr-bgp-bfd-
strict-mode-05.txt>.
[I-D.ietf-lsvr-l3dl] [I-D.ietf-lsvr-l3dl]
Bush, R., Austein, R., and K. Patel, "Layer 3 Discovery Bush, R., Austein, R., and K. Patel, "Layer 3 Discovery
and Liveness", draft-ietf-lsvr-l3dl-07 (work in progress), and Liveness", Work in Progress, Internet-Draft, draft-
January 2021. ietf-lsvr-l3dl-07, 26 January 2021,
<https://www.ietf.org/archive/id/draft-ietf-lsvr-l3dl-
07.txt>.
[I-D.ietf-lsvr-l3dl-signing] [I-D.ietf-lsvr-l3dl-signing]
Bush, R. and R. Austein, "Layer 3 Discovery and Liveness Bush, R., Housley, R., and R. Austein, "Layer-3 Discovery
Signing", draft-ietf-lsvr-l3dl-signing-01 (work in and Liveness Signing", Work in Progress, Internet-Draft,
progress), January 2021. draft-ietf-lsvr-l3dl-signing-02, 12 February 2021,
<https://www.ietf.org/archive/id/draft-ietf-lsvr-l3dl-
signing-02.txt>.
[I-D.ietf-lsvr-l3dl-ulpc] [I-D.ietf-lsvr-l3dl-ulpc]
Bush, R. and K. Patel, "L3DL Upper Layer Protocol Bush, R. and K. Patel, "L3DL Upper Layer Protocol
Configuration", draft-ietf-lsvr-l3dl-ulpc-01 (work in Configuration", Work in Progress, Internet-Draft, draft-
progress), January 2021. ietf-lsvr-l3dl-ulpc-01, 26 January 2021,
<https://www.ietf.org/archive/id/draft-ietf-lsvr-l3dl-
ulpc-01.txt>.
[I-D.ietf-lsvr-lsoe] [I-D.ietf-lsvr-lsoe]
Bush, R., Austein, R., and K. Patel, "Link State Over Bush, R., Austein, R., and K. Patel, "Link State Over
Ethernet", draft-ietf-lsvr-lsoe-01 (work in progress), Ethernet", Work in Progress, Internet-Draft, draft-ietf-
February 2019. lsvr-lsoe-01, 17 February 2019,
<https://www.ietf.org/archive/id/draft-ietf-lsvr-lsoe-
01.txt>.
[I-D.raszuk-idr-bgp-auto-discovery] [I-D.raszuk-idr-bgp-auto-discovery]
Raszuk, R., Mitchell, J., Kumari, W., Patel, K., and J. Raszuk, R., Mitchell, J., Kumari, W., Patel, K., and J.
Scudder, "BGP Auto Discovery", draft-raszuk-idr-bgp-auto- Scudder, "BGP Auto Discovery", Work in Progress, Internet-
discovery-06 (work in progress), December 2019. Draft, draft-raszuk-idr-bgp-auto-discovery-06, 11 December
2019, <https://www.ietf.org/archive/id/draft-raszuk-idr-
bgp-auto-discovery-06.txt>.
[I-D.raszuk-idr-bgp-auto-session-setup] [I-D.raszuk-idr-bgp-auto-session-setup]
Raszuk, R., "BGP Automated Session Setup", draft-raszuk- Raszuk, R., "BGP Automated Session Setup", Work in
idr-bgp-auto-session-setup-01 (work in progress), December Progress, Internet-Draft, draft-raszuk-idr-bgp-auto-
2019. session-setup-01, 11 December 2019,
<https://www.ietf.org/archive/id/draft-raszuk-idr-bgp-
auto-session-setup-01.txt>.
[I-D.xu-idr-neighbor-autodiscovery] [I-D.xu-idr-neighbor-autodiscovery]
Xu, X., Talaulikar, K., Bi, K., Tantsura, J., and N. Xu, X., Talaulikar, K., Bi, K., Tantsura, J., and N.
Triantafillis, "BGP Neighbor Discovery", draft-xu-idr- Triantafillis, "BGP Neighbor Discovery", Work in Progress,
neighbor-autodiscovery-12 (work in progress), November Internet-Draft, draft-xu-idr-neighbor-autodiscovery-12, 26
2019. November 2019, <https://www.ietf.org/archive/id/draft-xu-
idr-neighbor-autodiscovery-12.txt>.
[RFC0826] Plummer, D., "An Ethernet Address Resolution Protocol: Or [RFC0826] Plummer, D., "An Ethernet Address Resolution Protocol: Or
Converting Network Protocol Addresses to 48.bit Ethernet Converting Network Protocol Addresses to 48.bit Ethernet
Address for Transmission on Ethernet Hardware", STD 37, Address for Transmission on Ethernet Hardware", STD 37,
RFC 826, DOI 10.17487/RFC0826, November 1982, RFC 826, DOI 10.17487/RFC0826, November 1982,
<https://www.rfc-editor.org/info/rfc826>. <https://www.rfc-editor.org/info/rfc826>.
[RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 [RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5
Signature Option", RFC 2385, DOI 10.17487/RFC2385, August Signature Option", RFC 2385, DOI 10.17487/RFC2385, August
1998, <https://www.rfc-editor.org/info/rfc2385>. 1998, <https://www.rfc-editor.org/info/rfc2385>.
skipping to change at page 14, line 47 skipping to change at page 15, line 24
interface addresses. interface addresses.
LLDP has a limitation that all information must fit in a single PDU LLDP has a limitation that all information must fit in a single PDU
(it does not support fragmentation / a "session"). There is an early (it does not support fragmentation / a "session"). There is an early
LLDPv2 development effort to extend this in the IEEE. LLDPv2 development effort to extend this in the IEEE.
[I-D.acee-idr-lldp-peer-discovery] describes how to use the LLDP IETF [I-D.acee-idr-lldp-peer-discovery] describes how to use the LLDP IETF
Organizationally Specific TLV to augment the LLDP TLV set to exchange Organizationally Specific TLV to augment the LLDP TLV set to exchange
BGP Config Sub-TLVs signaling: BGP Config Sub-TLVs signaling:
o AFI * AFI
o IP address (IPv4 or IPv6) * IP address (IPv4 or IPv6)
o Local AS number * Local AS number
o Local BGP Identifier (AKA, BGP Router ID) * Local BGP Identifier (AKA, BGP Router ID)
o Session Group-ID; i.e., the BGP Device Role * Session Group-ID; i.e., the BGP Device Role
o BGP Session Capabilities * BGP Session Capabilities
o Key Chain * Key Chain
o Local Address (as BGP Next Hop). * Local Address (as BGP Next Hop).
A.1.2. L3DL based Approach A.1.2. L3DL based Approach
L3DL [I-D.ietf-lsvr-l3dl] is an ongoing development in the IETF LSVR L3DL [I-D.ietf-lsvr-l3dl] is an ongoing development in the IETF LSVR
Working Group with the goal of discovering IP Layer-3 attributes of Working Group with the goal of discovering IP Layer-3 attributes of
links, such as neighbor IP addressing, logical link IP encapsulation links, such as neighbor IP addressing, logical link IP encapsulation
abilities, and link liveness which may then be disseminated for the abilities, and link liveness which may then be disseminated for the
use of BGP-SPF and similar protocols. use of BGP-SPF and similar protocols.
L3DL Upper Layer Protocol Configuration, [I-D.ietf-lsvr-l3dl-ulpc], L3DL Upper Layer Protocol Configuration, [I-D.ietf-lsvr-l3dl-ulpc],
details signaling the minimal set of parameters needed to start a BGP details signaling the minimal set of parameters needed to start a BGP
session with a discovered peer. Details such as loopback peering are session with a discovered peer. Details such as loopback peering are
handled by attributes in the L3DL protocol itself. The information handled by attributes in the L3DL protocol itself. The information
which can be discovered by L3DL is: which can be discovered by L3DL is:
o AS number * AS number
o Local IP address, IPv4 or IPv6, and * Local IP address, IPv4 or IPv6, and
o BGP Authentication. * BGP Authentication.
L3DL and L3DL-ULPC have well-specified security mechanisms, see L3DL and L3DL-ULPC have well-specified security mechanisms, see
[I-D.ietf-lsvr-l3dl-signing]. [I-D.ietf-lsvr-l3dl-signing].
The functionality of L3DL-ULPC is similar but not quite the same as The functionality of L3DL-ULPC is similar but not quite the same as
the needs of IDR Design Team. For example, L3DL is designed to meet the needs of IDR Design Team. For example, L3DL is designed to meet
more complex needs. L3DL's predecessor, LSOE [I-D.ietf-lsvr-lsoe], more complex needs. L3DL's predecessor, LSOE [I-D.ietf-lsvr-lsoe],
was simpler and might be a better candidate for adaptation. If was simpler and might be a better candidate for adaptation. If
needed, the design of LSOE may be customized for the needs of BGP needed, the design of LSOE may be customized for the needs of BGP
peer auto- disovery. peer auto- disovery.
skipping to change at page 16, line 41 skipping to change at page 17, line 21
A.3.1. New BGP Hello Message based Approach A.3.1. New BGP Hello Message based Approach
[I-D.xu-idr-neighbor-autodiscovery] describes a BGP neighbor [I-D.xu-idr-neighbor-autodiscovery] describes a BGP neighbor
discovery mechanism which is based on a newly defined UDP based BGP discovery mechanism which is based on a newly defined UDP based BGP
Hello message. The BGP Hello message is sent in multicast to Hello message. The BGP Hello message is sent in multicast to
discover the directly connected BGP peers. According to the message discover the directly connected BGP peers. According to the message
header format and the TLVs carried in the message, the information header format and the TLVs carried in the message, the information
which can be signaled is: which can be signaled is:
o AS number * AS number
o BGP Identifier * BGP Identifier
o Accepted ASN list * Accepted ASN list
o Peering address (IPv4 or IPv6) * Peering address (IPv4 or IPv6)
o Local prefix (for loopback) * Local prefix (for loopback)
o Link attributes * Link attributes
o Neighbor state * Neighbor state
o BGP Authentication * BGP Authentication
The mechanisms in this draft do not currently handle fragmentation. The mechanisms in this draft do not currently handle fragmentation.
The mechanism in this draft is perhaps unique among the other The mechanism in this draft is perhaps unique among the other
proposals in requiring bi-directional state. proposals in requiring bi-directional state.
A.3.2. BGP OPEN Message based Approach A.3.2. BGP OPEN Message based Approach
[I-D.raszuk-idr-bgp-auto-session-setup] describes a BGP neighbor [I-D.raszuk-idr-bgp-auto-session-setup] describes a BGP neighbor
discovery mechanism by reusing BGP OPEN message format with newly discovery mechanism by reusing BGP OPEN message format with newly
defined UDP port. The message is called BGP Session Explorer (BSE) defined UDP port. The message is called BGP Session Explorer (BSE)
packet and is sent in multicast. Since the message format is the packet and is sent in multicast. Since the message format is the
same as BGP OPEN, the information which can be signaled is: same as BGP OPEN, the information which can be signaled is:
o AS number * AS number
o BGP Identifier * BGP Identifier
o Peering address * Peering address
The mechanism is currently under-specified with respect to a number The mechanism is currently under-specified with respect to a number
of similar properties described elsewhere. A general implication is of similar properties described elsewhere. A general implication is
that those properties - and others providing for extensibility of the that those properties - and others providing for extensibility of the
auto-discovery mechanism - would need to be added to the BGP OPEN auto-discovery mechanism - would need to be added to the BGP OPEN
message and deal with the related impacts on the BGP session's message and deal with the related impacts on the BGP session's
finite-state machine. finite-state machine.
BGP PDUs, including the OPEN message, may be up to 4k in size. Since BGP PDUs, including the OPEN message, may be up to 4k in size. Since
this mechanism leverages Layer 3 multicast, a PDU fragmentation this mechanism leverages Layer 3 multicast, a PDU fragmentation
mechanism may need to be described. mechanism may need to be described.
A.3.3. Bootstrapping BGP via BGP A.3.3. Bootstrapping BGP via BGP
[I-D.raszuk-idr-bgp-auto-discovery] describes a new BGP address [I-D.raszuk-idr-bgp-auto-discovery] describes a new BGP address
family. The NLRI carries a Group ID + BGP Identifier as the key. A family. The NLRI carries a Group ID + BGP Identifier as the key. A
new BGP Path Attribute carries information about the sessions: new BGP Path Attribute carries information about the sessions:
o AS Number * AS Number
o AFI/SAFI * AFI/SAFI
o BGP Identifier * BGP Identifier
o Peer Transport Address * Peer Transport Address
o Flags to declare a session for information only, to force a reset * Flags to declare a session for information only, to force a reset
of a session on parameter changes, etc. of a session on parameter changes, etc.
Since the BGP auto-discovery state is carried by BGP, it inherits the Since the BGP auto-discovery state is carried by BGP, it inherits the
security implications of the underlying BGP session. security implications of the underlying BGP session.
PDU size considerations are identical to those of a BGP UPDATE PDU size considerations are identical to those of a BGP UPDATE
message. message.
Similarly, extensibility considerations would rely on either the new Similarly, extensibility considerations would rely on either the new
BGP Path Attribute, or one yet to be defined. BGP Path Attribute, or one yet to be defined.
A.3.4. Bootstrapping BGP via OSPF A.3.4. Bootstrapping BGP via OSPF
[I-D.acee-ospf-bgp-rr] describes a mechanism to learn BGP Route [I-D.acee-ospf-bgp-rr] describes a mechanism to learn BGP Route
Reflectors via OSPFv2/OSPFv3 LSAs. Multiple types of scopes are Reflectors via OSPFv2/OSPFv3 LSAs. Multiple types of scopes are
defined for these LSAs to help constrain where they are advertised in defined for these LSAs to help constrain where they are advertised in
an OSPF domain. an OSPF domain.
The BGP Route Reflector TLV contains: The BGP Route Reflector TLV contains:
o Local AS Number * Local AS Number
o IPv4 or IPv6 Address of the Route Reflector * IPv4 or IPv6 Address of the Route Reflector
o A list of AFI/SAFIs supported by the Route Reflector * A list of AFI/SAFIs supported by the Route Reflector
The BGP Route Reflector TLV may be advertised more than once, The BGP Route Reflector TLV may be advertised more than once,
potentially to describe different IP transport endpoints. potentially to describe different IP transport endpoints.
This mechanism does not provide for security properties of the BGP This mechanism does not provide for security properties of the BGP
session or transport properties such as BFD or GTSM. session or transport properties such as BFD or GTSM.
Authors' Addresses Authors' Addresses
Randy Bush Randy Bush
Arrcus, Inc. & Internet Initiative Japan Arrcus, Inc. & Internet Initiative Japan
5147 Crystal Springs 5147 Crystal Springs
Bainbridge Island, WA 98110 Bainbridge Island, WA 98110
US United States of America
Email: randy@psg.com Email: randy@psg.com
Jie Dong Jie Dong
Huawei Technologies Huawei Technologies
Huawei Campus, No. 156 Beiqing Road Huawei Campus, No. 156 Beiqing Road
Beijing 100095 Beijing
100095
China China
Email: jie.dong@huawei.com Email: jie.dong@huawei.com
Jeffrey Haas (editor) Jeffrey Haas (editor)
Juniper Networks Juniper Networks
1133 Innovation Way 1133 Innovation Way
Sunnyvale, CA 94089 Sunnyvale, CA 94089
US United States of America
Email: jhaas@juniper.net Email: jhaas@juniper.net
Warren Kumari (editor) Warren Kumari (editor)
Google Google
1600 Amphitheatre Parkway 1600 Amphitheatre Parkway
Mountain View, CA 94043 Mountain View, CA 94043
US United States of America
Email: warren@kumari.net Email: warren@kumari.net
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