--- 1/draft-ietf-idr-bgp-autoconf-considerations-00.txt 2021-06-25 16:13:09.807912517 -0700 +++ 2/draft-ietf-idr-bgp-autoconf-considerations-01.txt 2021-06-25 16:13:09.847913519 -0700 @@ -1,23 +1,23 @@ Network Working Group R. Bush Internet-Draft Arrcus, Inc. & Internet Initiative Japan Intended status: Informational J. Dong -Expires: September 9, 2021 Huawei Technologies +Expires: 27 December 2021 Huawei Technologies J. Haas, Ed. Juniper Networks W. Kumari, Ed. Google - March 8, 2021 + 25 June 2021 Requirements and Considerations in BGP Peer Auto-Configuration - draft-ietf-idr-bgp-autoconf-considerations-00 + draft-ietf-idr-bgp-autoconf-considerations-01 Abstract This draft is an exploration of the requirements, the alternatives, 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 Autoconf Design Team. The current target environment is the datacenter. This document is not intended to become an RFC. @@ -38,76 +38,76 @@ 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 https://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 September 9, 2021. + This Internet-Draft will expire on 27 December 2021. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal - Provisions Relating to IETF Documents - (https://trustee.ietf.org/license-info) in effect on the date of - publication of this document. Please review these documents - carefully, as they describe your rights and restrictions with respect - to this document. Code Components extracted from this document must - include Simplified BSD License text as described in Section 4.e of - the Trust Legal Provisions and are provided without warranty as - described in the Simplified BSD License. + Provisions Relating to IETF Documents (https://trustee.ietf.org/ + license-info) in effect on the date of publication of this document. + Please review these documents carefully, as they describe your rights + and restrictions with respect to this document. Code Components + extracted from this document must include Simplified BSD License text + as described in Section 4.e of the Trust Legal Provisions and are + provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Design Team Determinations . . . . . . . . . . . . . . . . . 3 2.1. Problem Scope . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Simplicity . . . . . . . . . . . . . . . . . . . . . . . 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 - 2.4. BGP Auto-Discovery Protocol Transport Requirements . . . 5 + 2.4. BGP Auto-Discovery Protocol Transport Requirements . . . 4 2.5. Operator Configuration . . . . . . . . . . . . . . . . . 5 - 3. Design Principle Considerations . . . . . . . . . . . . . . . 6 - 3.1. Transport Considerations . . . . . . . . . . . . . . . . 6 + 3. Design Principle Considerations . . . . . . . . . . . . . . . 5 + 3.1. Transport Considerations . . . . . . . . . . . . . . . . 5 3.2. Auto-Discovery Protocol Timing Considerations . . . . . . 6 - 3.3. Relationship with BGP . . . . . . . . . . . . . . . . . . 7 - 3.4. Session Selection Considerations . . . . . . . . . . . . 7 - 3.5. Operational Trust Considerations . . . . . . . . . . . . 7 - 3.6. Error Handling Considerations . . . . . . . . . . . . . . 9 + 3.3. Relationship with BGP . . . . . . . . . . . . . . . . . . 6 + 3.4. Session Selection Considerations . . . . . . . . . . . . 6 + 3.5. Session Stability Considerations . . . . . . . . . . . . 7 + 3.6. Operational Trust Considerations . . . . . . . . . . . . 7 + 3.7. Error Handling Considerations . . . . . . . . . . . . . . 9 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 5.1. BGP Transport Security Considerations . . . . . . . . . . 10 5.2. Auto-discovery Protocol Considerations . . . . . . . . . 10 5.2.1. Potential Scopes of an Auto-discovery Protocol . . . 10 5.2.2. Desired Security Properties of the Auto-discovery Protocols . . . . . . . . . . . . . . . . . . . . . . 11 - 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 + 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1. Normative References . . . . . . . . . . . . . . . . . . 12 7.2. Informative References . . . . . . . . . . . . . . . . . 12 Appendix A. Analysis of Candidate Approaches . . . . . . . . . . 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.2. Link-Local Discovery . . . . . . . . . . . . . . . . . . 15 + A.2. Link-Local Discovery . . . . . . . . . . . . . . . . . . 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.3.3. Bootstrapping BGP via BGP . . . . . . . . . . . . . . 17 + A.3.3. Bootstrapping BGP via BGP . . . . . . . . . . . . . . 18 A.3.4. Bootstrapping BGP via OSPF . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 1. Introduction This draft is an exploration of the requirements, the alternatives, 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 Autoconf Design Team. The current target environment is the datacenter. @@ -125,141 +125,122 @@ The auto-discovery mechanism is designed to be simple. The goal is to select BGP Speakers where a BGP session may be successfully negotiated for a particular purpose. The auto-discovery mechanism will not replace or conflict with data exchanged by the BGP FSM, including its OPEN message. 2.3. BGP Auto-Discovery Protocol State Requirements - Tersely, the required state that MUST be carried by the BGP Auto- - Discovery Protocol for a discovered session include: + The Auto-Discovery Protocol is used discover BGP Session end-points. + 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 - o Transport security parameters - o GTSM [RFC5082] configuration, if any - o BFD [RFC5880] configuration, if any + The required state that MUST be carried by the BGP Auto-Discovery + Protocol for a discovered session includes: - BGP Session Protocol State: + * IP addresses + * Transport security parameters + * GTSM [RFC5082] configuration, if any + * BGP Session Protocol State Version Number - o AS Numbers - o BGP Identifier - o Supported AFI/SAFIs - o Device Role + BGP Session Protocol State, discovered at BGP OPEN: - Once this information has been learned, discovery has been completed. - The BGP Speaker has the necessary information to determine if it - wishes to open a BGP session with the discovered BGP Speaker. It can - then then initiate a BGP session with the discovered BGP Speaker. + * AS Numbers + * BGP Identifier + * Supported AFI/SAFIs -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. - 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, potentially exchange additional information to bootstrap 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, - layer 3 liveness mechanisms such as BFD, and support for GTSM. - o Transport security parameters include protocol - such as plain + and support for GTSM. + * Transport security parameters include protocol - such as plain TCP, TCP-AO [RFC5925], IPsec [RFC4301], TCP-MD5 [RFC2385] - and necessary configuration for that protocol. Some example considerations for this are represented in YANG Data Model for Key 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 - 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, supported address families/subsequent-address families (AFI/ - SAFIs), and device roles. - -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. + SAFIs). 2.4. BGP Auto-Discovery Protocol Transport Requirements BGP Auto-Discovery Protocol State may be carried in multiple protocols operating in different transport layers. Implementations supporting more than one protocol for this state must have a mechanism for consistently selecting discovered BGP sessions. The BGP Identifier, which is carried by the BGP OPEN message, can help detect sessions to the same BGP Speaker carried in multiple protocols. 2.5. Operator Configuration With BGP auto-discovery, some configuration of BGP is still needed. Operator configuration should be able to decide at least the 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. - - * Permit the matching of device role from the discovery protocol - as part of peer selection. - o Decide the parameters to use. For example: - - * IP addressing: IPv4 or IPv6. - * Interface for peering: Loopback, or Direct. - * Any special forwarding or routing needed for reaching the + * Decide the parameters to use. For example: + - 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. - * AS numbering. - * BGP Transport Security Parameters. - * BGP Policy that is appropriate for the type of discovered + - AS numbering. + - BGP Transport Security Parameters. + - BGP Policy that is appropriate for the type of discovered session. In addition to actually forming the BGP sessions, a common deployment model may also be the so called "validation" model. In this model, the operator configures the BGP sessions manually, and uses the - information collected/populated by the BGP Autoconf mechanism to - validate that the sessions are correct. + information collected/populated by the BGP Auto-Configuration + mechanism to validate that the sessions are correct. 3. Design Principle Considerations This section summarizes the considerations of possible criteria for the design of a BGP auto-discovery mechanism, which may need further discussion in a wider community than the design team; for example, the IDR Working Group. 3.1. Transport Considerations The network layer of the discovery mechanism may impact the scoping of the deployment of the auto-discovery mechanism. - o Layer 2: For example, based on Ethernet. - o Layer 3: Which is generic for any link-layer protocol. + * Layer 2: For example, based on Ethernet. + * Layer 3: Which is generic for any link-layer protocol. Potentially leveraging existing protocols deployed in the data center. The length of messages supported by the protocol. How extensible the protocol is to carry future state for BGP auto- configuration. 3.2. Auto-Discovery Protocol Timing Considerations @@ -267,41 +248,41 @@ Establishing a reasonable expectation for the timeliness of auto- configuration is desirable. When a link is plugged-in, one shouldn't have to wait minutes for potential peers to be discovered and BGP session establishment attempted. For protocols crafted explicitly for BGP auto-configuration, the time for discovery should be a reasonable amount of time; for example ten seconds or less. Since discovery mechanisms may become very chatty when utilized by a number of devices on shared networks, the protocol should not impose 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. 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 BGP Speaker on that network, the auto-discovery protocol MAY quiesce once the discovered BGP session has become Established. In cases where the auto-discovery protocol is carried as state in another protocol, that protocol will have its own timeliness considerations. The auto-discovery mechanism SHOULD NOT interfere with the timing of the existing protocol. 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. - 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 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. 3.4. Session Selection Considerations Candidate BGP sessions to a given BGP Speaker may be discovered by one or more auto-discovery protocols. Even for a single protocol, multiple transport session endpoints may be discovered for the same BGP Speaker. These different sessions may be required for supporting different address families, such as IPv4/IPv6, depending on the BGP operational practices for that device. Examples include a distinct @@ -312,21 +293,29 @@ 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- discovery protocol. When multiple mechanisms exist to discovery the same BGP speaker in an implementation, that implementation MUST document the process by which it chooses discovered peers. Those implementations also MUST describe interactions with their protocol state machinery for each 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 requirements. Some of this will be driven by the size, complexity and operational practices of the operator. For example, some operators have very strict physical protection of the datacenter, and their deployment model assumes that anything which plugs into devices in the datacenter is, by definition, trusted. Other operators take a very different approach, and assume the least possible amount of trust. @@ -354,73 +343,73 @@ validation of the datacenter fabric, and ongoing "sanity-checking" to confirm that the datacenter is correctly cabled, and that the BGP sessions which have been configured from the database match what the autodiscovered sessions would have created. Over time, if the BGP Autoconf solution proves to be successful, reliable, and scaleable, operators may begin using it as the primary source of record. Closely related to these considerations is the "scope" of the discovery process. It is expected that many operators will wish to 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 all of the trust and deployment models, and we will need to prioritize which set(s) of deployment scenarios are the most important for the Working Group to solve. Trust/Operational deployment driven requirements. The solution 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 "Only 100GE interfaces"). This is likely an implementation 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 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 autoconfiguring everything, it should also support filtering or limiting the session according to configured policy. (Likely an implementation detail.) - - o Support preconfigured authentication systems. This is an area + * Support preconfigured authentication systems. This is an area where more discussion is needed! The solution MUST also support a "no authentication" mode. Negotiated keying solutions, such as IKE, may be desireable but not mandatory for the solution. - o Support Ethernet sub-interfaces such as VLANs. - o Support non-Ethernet interfaces. This may include tunnels. + * Support Ethernet sub-interfaces such as VLANs. + * 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 potential BGP sessions and provide enough information for a BGP Speaker to start a BGP session. It is possible for the information present in the auto-discovery protocol to not match the session's information. Such mis-matches will result in different classes of 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 transport security configuration, etc. In these cases, a BGP Speaker attempts to establish a session and fails. Implementations SHOULD provide a way to clear such discovered 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. In this case, the implementation may wish to disconnect from the BGP session and exclude it from further connection attempts. The implementation SHOULD raise a visible fault to the operator. The implementation SHOULD provide a mechanism to permit further 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 access to the operator for discovered BGP sessions from the auto- discovery protocol; for example via the user-interface. The implementation SHOULD permit a manually configured BGP session to conflict with information present in the auto-discovery protocol, but SHOULD raise an alarm with the operator that this has been done. 4. IANA Considerations @@ -532,64 +521,88 @@ [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 7.2. Informative References [I-D.acee-idr-lldp-peer-discovery] Lindem, A., Patel, K., Zandi, S., Haas, J., and X. Xu, "BGP Logical Link Discovery Protocol (LLDP) Peer - Discovery", draft-acee-idr-lldp-peer-discovery-08 (work in - progress), December 2020. + Discovery", Work in Progress, Internet-Draft, draft-acee- + idr-lldp-peer-discovery-08, 7 December 2020, + . [I-D.acee-ospf-bgp-rr] Lindem, A., Patel, K., Zandi, S., and R. Raszuk, "OSPF Extensions for Advertising/Signaling BGP Route Reflector - Information", draft-acee-ospf-bgp-rr-01 (work in - progress), September 2017. + Information", Work in Progress, Internet-Draft, draft- + acee-ospf-bgp-rr-01, 7 September 2017, + . + + [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, + . [I-D.ietf-lsvr-l3dl] Bush, R., Austein, R., and K. Patel, "Layer 3 Discovery - and Liveness", draft-ietf-lsvr-l3dl-07 (work in progress), - January 2021. + and Liveness", Work in Progress, Internet-Draft, draft- + ietf-lsvr-l3dl-07, 26 January 2021, + . [I-D.ietf-lsvr-l3dl-signing] - Bush, R. and R. Austein, "Layer 3 Discovery and Liveness - Signing", draft-ietf-lsvr-l3dl-signing-01 (work in - progress), January 2021. + Bush, R., Housley, R., and R. Austein, "Layer-3 Discovery + and Liveness Signing", Work in Progress, Internet-Draft, + draft-ietf-lsvr-l3dl-signing-02, 12 February 2021, + . [I-D.ietf-lsvr-l3dl-ulpc] Bush, R. and K. Patel, "L3DL Upper Layer Protocol - Configuration", draft-ietf-lsvr-l3dl-ulpc-01 (work in - progress), January 2021. + Configuration", Work in Progress, Internet-Draft, draft- + ietf-lsvr-l3dl-ulpc-01, 26 January 2021, + . [I-D.ietf-lsvr-lsoe] Bush, R., Austein, R., and K. Patel, "Link State Over - Ethernet", draft-ietf-lsvr-lsoe-01 (work in progress), - February 2019. + Ethernet", Work in Progress, Internet-Draft, draft-ietf- + lsvr-lsoe-01, 17 February 2019, + . [I-D.raszuk-idr-bgp-auto-discovery] Raszuk, R., Mitchell, J., Kumari, W., Patel, K., and J. - Scudder, "BGP Auto Discovery", draft-raszuk-idr-bgp-auto- - discovery-06 (work in progress), December 2019. + Scudder, "BGP Auto Discovery", Work in Progress, Internet- + Draft, draft-raszuk-idr-bgp-auto-discovery-06, 11 December + 2019, . [I-D.raszuk-idr-bgp-auto-session-setup] - Raszuk, R., "BGP Automated Session Setup", draft-raszuk- - idr-bgp-auto-session-setup-01 (work in progress), December - 2019. + Raszuk, R., "BGP Automated Session Setup", Work in + Progress, Internet-Draft, draft-raszuk-idr-bgp-auto- + session-setup-01, 11 December 2019, + . [I-D.xu-idr-neighbor-autodiscovery] Xu, X., Talaulikar, K., Bi, K., Tantsura, J., and N. - Triantafillis, "BGP Neighbor Discovery", draft-xu-idr- - neighbor-autodiscovery-12 (work in progress), November - 2019. + Triantafillis, "BGP Neighbor Discovery", Work in Progress, + Internet-Draft, draft-xu-idr-neighbor-autodiscovery-12, 26 + November 2019, . [RFC0826] Plummer, D., "An Ethernet Address Resolution Protocol: Or Converting Network Protocol Addresses to 48.bit Ethernet Address for Transmission on Ethernet Hardware", STD 37, RFC 826, DOI 10.17487/RFC0826, November 1982, . [RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 Signature Option", RFC 2385, DOI 10.17487/RFC2385, August 1998, . @@ -651,46 +664,46 @@ interface addresses. LLDP has a limitation that all information must fit in a single PDU (it does not support fragmentation / a "session"). There is an early LLDPv2 development effort to extend this in the IEEE. [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 BGP Config Sub-TLVs signaling: - o AFI - o IP address (IPv4 or IPv6) - o Local AS number - o Local BGP Identifier (AKA, BGP Router ID) - o Session Group-ID; i.e., the BGP Device Role - o BGP Session Capabilities - o Key Chain - o Local Address (as BGP Next Hop). + * AFI + * IP address (IPv4 or IPv6) + * Local AS number + * Local BGP Identifier (AKA, BGP Router ID) + * Session Group-ID; i.e., the BGP Device Role + * BGP Session Capabilities + * Key Chain + * Local Address (as BGP Next Hop). A.1.2. L3DL based Approach 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 links, such as neighbor IP addressing, logical link IP encapsulation abilities, and link liveness which may then be disseminated for the use of BGP-SPF and similar protocols. L3DL Upper Layer Protocol Configuration, [I-D.ietf-lsvr-l3dl-ulpc], details signaling the minimal set of parameters needed to start a BGP session with a discovered peer. Details such as loopback peering are handled by attributes in the L3DL protocol itself. The information which can be discovered by L3DL is: - o AS number - o Local IP address, IPv4 or IPv6, and - o BGP Authentication. + * AS number + * Local IP address, IPv4 or IPv6, and + * BGP Authentication. L3DL and L3DL-ULPC have well-specified security mechanisms, see [I-D.ietf-lsvr-l3dl-signing]. 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 more complex needs. L3DL's predecessor, LSOE [I-D.ietf-lsvr-lsoe], was simpler and might be a better candidate for adaptation. If needed, the design of LSOE may be customized for the needs of BGP peer auto- disovery. @@ -741,120 +754,121 @@ A.3.1. New BGP Hello Message based Approach [I-D.xu-idr-neighbor-autodiscovery] describes a BGP neighbor discovery mechanism which is based on a newly defined UDP based BGP Hello message. The BGP Hello message is sent in multicast to discover the directly connected BGP peers. According to the message header format and the TLVs carried in the message, the information which can be signaled is: - o AS number - o BGP Identifier - o Accepted ASN list - o Peering address (IPv4 or IPv6) - o Local prefix (for loopback) - o Link attributes - o Neighbor state - o BGP Authentication + * AS number + * BGP Identifier + * Accepted ASN list + * Peering address (IPv4 or IPv6) + * Local prefix (for loopback) + * Link attributes + * Neighbor state + * BGP Authentication The mechanisms in this draft do not currently handle fragmentation. The mechanism in this draft is perhaps unique among the other proposals in requiring bi-directional state. A.3.2. BGP OPEN Message based Approach [I-D.raszuk-idr-bgp-auto-session-setup] describes a BGP neighbor discovery mechanism by reusing BGP OPEN message format with newly defined UDP port. The message is called BGP Session Explorer (BSE) packet and is sent in multicast. Since the message format is the same as BGP OPEN, the information which can be signaled is: - o AS number - o BGP Identifier - o Peering address + * AS number + * BGP Identifier + * Peering address The mechanism is currently under-specified with respect to a number of similar properties described elsewhere. A general implication is that those properties - and others providing for extensibility of the auto-discovery mechanism - would need to be added to the BGP OPEN message and deal with the related impacts on the BGP session's finite-state machine. BGP PDUs, including the OPEN message, may be up to 4k in size. Since this mechanism leverages Layer 3 multicast, a PDU fragmentation mechanism may need to be described. A.3.3. Bootstrapping BGP via BGP [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 new BGP Path Attribute carries information about the sessions: - o AS Number - o AFI/SAFI - o BGP Identifier - o Peer Transport Address - o Flags to declare a session for information only, to force a reset + * AS Number + * AFI/SAFI + * BGP Identifier + * Peer Transport Address + * Flags to declare a session for information only, to force a reset of a session on parameter changes, etc. Since the BGP auto-discovery state is carried by BGP, it inherits the security implications of the underlying BGP session. PDU size considerations are identical to those of a BGP UPDATE message. Similarly, extensibility considerations would rely on either the new BGP Path Attribute, or one yet to be defined. A.3.4. Bootstrapping BGP via OSPF [I-D.acee-ospf-bgp-rr] describes a mechanism to learn BGP Route Reflectors via OSPFv2/OSPFv3 LSAs. Multiple types of scopes are defined for these LSAs to help constrain where they are advertised in an OSPF domain. The BGP Route Reflector TLV contains: - o Local AS Number - o IPv4 or IPv6 Address of the Route Reflector - o A list of AFI/SAFIs supported by the Route Reflector + * Local AS Number + * IPv4 or IPv6 Address of the Route Reflector + * A list of AFI/SAFIs supported by the Route Reflector The BGP Route Reflector TLV may be advertised more than once, potentially to describe different IP transport endpoints. This mechanism does not provide for security properties of the BGP session or transport properties such as BFD or GTSM. Authors' Addresses - Randy Bush Arrcus, Inc. & Internet Initiative Japan 5147 Crystal Springs Bainbridge Island, WA 98110 - US + United States of America Email: randy@psg.com Jie Dong Huawei Technologies Huawei Campus, No. 156 Beiqing Road - Beijing 100095 + Beijing + 100095 China Email: jie.dong@huawei.com Jeffrey Haas (editor) Juniper Networks 1133 Innovation Way Sunnyvale, CA 94089 - US + United States of America Email: jhaas@juniper.net + Warren Kumari (editor) Google 1600 Amphitheatre Parkway Mountain View, CA 94043 - US + United States of America Email: warren@kumari.net