--- 1/draft-ietf-mpls-lsp-ping-lag-multipath-05.txt 2019-03-05 18:13:10.189970487 -0800 +++ 2/draft-ietf-mpls-lsp-ping-lag-multipath-06.txt 2019-03-05 18:13:10.249971956 -0800 @@ -1,27 +1,27 @@ Internet Engineering Task Force N. Akiya Internet-Draft Big Switch Networks Updates: 8029 (if approved) G. Swallow Intended status: Standards Track Cisco Systems -Expires: April 26, 2019 S. Litkowski +Expires: September 6, 2019 S. Litkowski B. Decraene Orange J. Drake Juniper Networks M. Chen Huawei - October 23, 2018 + March 05, 2019 Label Switched Path (LSP) Ping/Trace Multipath Support for Link Aggregation Group (LAG) Interfaces - draft-ietf-mpls-lsp-ping-lag-multipath-05 + draft-ietf-mpls-lsp-ping-lag-multipath-06 Abstract This document defines extensions to the MPLS Label Switched Path (LSP) Ping and Traceroute mechanisms as specified in RFC 8029. The extensions allow the MPLS LSP Ping and Traceroute mechanisms to discover and exercise specific paths of Layer 2 (L2) Equal-Cost Multipath (ECMP) over Link Aggregation Group (LAG) interfaces. Additionally, a mechanism is defined to enable determination of the capabilities of an LSR supported. @@ -44,145 +44,145 @@ 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 April 26, 2019. + This Internet-Draft will expire on September 6, 2019. Copyright Notice - Copyright (c) 2018 IETF Trust and the persons identified as the + Copyright (c) 2019 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 - 1.2. Background . . . . . . . . . . . . . . . . . . . . . . . 3 + 1.2. Background . . . . . . . . . . . . . . . . . . . . . . . 4 2. Overview of Solution . . . . . . . . . . . . . . . . . . . . 4 3. LSR Capability Discovery . . . . . . . . . . . . . . . . . . 6 3.1. Initiator LSR Procedures . . . . . . . . . . . . . . . . 7 3.2. Responder LSR Procedures . . . . . . . . . . . . . . . . 7 - 4. Mechanism to Discover L2 ECMP Multipath . . . . . . . . . . . 7 - 4.1. Initiator LSR Procedures . . . . . . . . . . . . . . . . 7 + 4. Mechanism to Discover L2 ECMP Multipath . . . . . . . . . . . 8 + 4.1. Initiator LSR Procedures . . . . . . . . . . . . . . . . 8 4.2. Responder LSR Procedures . . . . . . . . . . . . . . . . 8 4.3. Additional Initiator LSR Procedures . . . . . . . . . . . 10 5. Mechanism to Validate L2 ECMP Traversal . . . . . . . . . . . 11 5.1. Incoming LAG Member Links Verification . . . . . . . . . 11 5.1.1. Initiator LSR Procedures . . . . . . . . . . . . . . 11 5.1.2. Responder LSR Procedures . . . . . . . . . . . . . . 12 5.1.3. Additional Initiator LSR Procedures . . . . . . . . . 12 5.2. Individual End-to-End Path Verification . . . . . . . . . 13 6. LSR Capability TLV . . . . . . . . . . . . . . . . . . . . . 14 7. LAG Description Indicator Flag: G . . . . . . . . . . . . . . 15 8. Local Interface Index Sub-TLV . . . . . . . . . . . . . . . . 16 9. Remote Interface Index Sub-TLV . . . . . . . . . . . . . . . 17 10. Detailed Interface and Label Stack TLV . . . . . . . . . . . 17 10.1. Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . . . 19 10.1.1. Incoming Label Stack Sub-TLV . . . . . . . . . . . . 19 10.1.2. Incoming Interface Index Sub-TLV . . . . . . . . . . 20 - 11. Security Considerations . . . . . . . . . . . . . . . . . . . 21 - 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 - 12.1. LSR Capability TLV . . . . . . . . . . . . . . . . . . . 21 - 12.1.1. LSR Capability Flags . . . . . . . . . . . . . . . . 21 - 12.2. Local Interface Index Sub-TLV . . . . . . . . . . . . . 22 - 12.2.1. Interface Index Flags . . . . . . . . . . . . . . . 22 - 12.3. Remote Interface Index Sub-TLV . . . . . . . . . . . . . 22 - 12.4. Detailed Interface and Label Stack TLV . . . . . . . . . 23 - 12.4.1. Sub-TLVs for TLV Type TBD4 . . . . . . . . . . . . . 23 - 12.5. DS Flags . . . . . . . . . . . . . . . . . . . . . . . . 23 - 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24 - 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 - 14.1. Normative References . . . . . . . . . . . . . . . . . . 24 - 14.2. Informative References . . . . . . . . . . . . . . . . . 24 + 11. Rate Limiting On Echo Request/Reply Messages . . . . . . . . 21 + 12. Security Considerations . . . . . . . . . . . . . . . . . . . 21 + 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 + 13.1. LSR Capability TLV . . . . . . . . . . . . . . . . . . . 21 + 13.1.1. LSR Capability Flags . . . . . . . . . . . . . . . . 22 + 13.2. Local Interface Index Sub-TLV . . . . . . . . . . . . . 22 + 13.2.1. Interface Index Flags . . . . . . . . . . . . . . . 22 + 13.3. Remote Interface Index Sub-TLV . . . . . . . . . . . . . 23 + 13.4. Detailed Interface and Label Stack TLV . . . . . . . . . 23 + 13.4.1. Sub-TLVs for TLV Type TBD4 . . . . . . . . . . . . . 23 + 13.5. DS Flags . . . . . . . . . . . . . . . . . . . . . . . . 24 + 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24 + 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 + 15.1. Normative References . . . . . . . . . . . . . . . . . . 24 + 15.2. Informative References . . . . . . . . . . . . . . . . . 25 Appendix A. LAG with intermediate L2 Switch Issues . . . . . . . 25 A.1. Equal Numbers of LAG Members . . . . . . . . . . . . . . 25 - A.2. Deviating Numbers of LAG Members . . . . . . . . . . . . 25 + A.2. Deviating Numbers of LAG Members . . . . . . . . . . . . 26 A.3. LAG Only on Right . . . . . . . . . . . . . . . . . . . . 26 A.4. LAG Only on Left . . . . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 1. Introduction 1.1. Terminology The following acronyms/terms are used in this document: o MPLS - Multiprotocol Label Switching. o LSP - Label Switched Path. o LSR - Label Switching Router. o ECMP - Equal-Cost Multipath. o LAG - Link Aggregation Group. - o Initiator LSR - LSR which sends MPLS echo request. + o Initiator LSR - The LSR which sends the MPLS echo request message. - o Responder LSR - LSR which receives MPLS echo request and sends - MPLS echo reply. + o Responder LSR - The LSR which receives the MPLS echo request + message and sends the MPLS echo reply message. 1.2. Background The MPLS Label Switched Path (LSP) Ping and Traceroute mechanisms [RFC8029] are powerful tools designed to diagnose all available Layer 3 (L3) paths of LSPs, including diagnostic coverage of L3 Equal-Cost Multipath (ECMP). In many MPLS networks, Link Aggregation Group (LAG) as defined in [IEEE802.1AX], which provides Layer 2 (L2) ECMP, is often used for various reasons. MPLS LSP Ping and Traceroute tools were not designed to discover and exercise specific paths of L2 ECMP. This raises a limitation for the following scenario when an LSP traverses over a LAG: o Label switching over some member links of the LAG is successful, but will be failed over other member links of the LAG. o MPLS echo request for the LSP over the LAG is load balanced on one of the member links which is label switching successfully. - With the above scenarios, MPLS LSP Ping and Traceroute will not be + With the above scenario, MPLS LSP Ping and Traceroute will not be able to detect the label switching failure of the problematic member link(s) of the LAG. In other words, lack of L2 ECMP diagnostic coverage can produce an outcome where MPLS LSP Ping and Traceroute can be blind to label switching failures over a problematic LAG interface. It is, thus, desirable to extend the MPLS LSP Ping and Traceroute to have deterministic diagnostic coverage of LAG interfaces. The need for a solution of this problem was motivated by issues encountered in live networks. 2. Overview of Solution This document defines an optional TLV to discover the capabilities of a responder LSR and extensions for use with the MPLS LSP Ping and Traceroute mechanisms to describe Multipath Information for individual LAG member links, thus allowing MPLS LSP Ping and Traceroute to discover and exercise specific paths of L2 ECMP over LAG interfaces. The reader is expected to be familiar with mechanics - of Downstream Mapping described in Section 3.3 of [RFC8029] and Downstream Detailed Mapping TLV (DDMAP) described in Section 3.4 of [RFC8029]. The solution consists of the MPLS echo request containing a DDMAP TLV and the optional LSR capability TLV to indicate that separate load balancing information for each L2 nexthop over LAG is desired in the MPLS echo reply. The Responder LSR places the same optional LSR capability TLV in the MPLS echo reply to provide acknowledgement back to the initiator LSR. It also adds, for each downstream LAG member, load balance information (i.e., multipath information and interface @@ -381,21 +381,21 @@ + The responder LSR MUST add an Multipath Data Sub-TLV for this LAG member link, if the received DDMAP TLV requested multipath information. Based on the procedures described above, every LAG member link will have a Local Interface Index Sub-TLV and a Multipath Data Sub-TLV entries in the DDMAP TLV. The order of the Sub-TLVs in the DDMAP TLV for a LAG member link MUST be Local Interface Index Sub-TLV immediately followed by Multipath Data Sub-TLV. A LAG member link - may also have a corresponding Remote Interface Index Sub-TLV. When a + MAY also have a corresponding Remote Interface Index Sub-TLV. When a Local Interface Index Sub-TLV, a Remote Interface Index-Sub-TLV and a Multipath Data Sub-TLV are placed in the DDMAP TLV to describe a LAG member link, they MUST be placed in the order of Local Interface Index Sub-TLV, Remote Interface Index-Sub-TLV and Multipath Data Sub- TLV. A responder LSR possessing a LAG interface with two member links would send the following DDMAP for this LAG interface: 0 1 2 3 @@ -480,21 +480,21 @@ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Multipath Data Sub-TLV LAG member link #1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label Stack Sub-TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: Example of DDMAP in MPLS Echo Request 5. Mechanism to Validate L2 ECMP Traversal - Section 4 defines the responder LSR procedures to constructs a DDMAP + Section 4 defines the responder LSR procedures to construct a DDMAP for a downstream LAG. The Remote Interface Index Sub-TLVs that describes the incoming LAG member links of the downstream LSR is optional, because this information from the downstream LSR is often not available on the responder LSR. In such case, the traversal of LAG member links can be validated with procedures described in Section 5.1. If LSRs can provide the Remote Interface Index Sub- TLVs, then the validation procedures described in Section 5.2 can be used. 5.1. Incoming LAG Member Links Verification @@ -555,21 +555,21 @@ o With specific entropy, the interface index of the incoming LAG member link at TTL=n+1. Expectation is that there's a relationship between the interface index of the outgoing LAG member link at TTL=n and the interface index of the incoming LAG member link at TTL=n+1 for all discovered entropies. In other words, set of entropies that load balances to outgoing LAG member link X at TTL=n should all reach the nexthop on same incoming LAG member link Y at TTL=n+1. - With additional logics, the initiator LSR can perform the following + With additional logic, the initiator LSR can perform the following checks in a scenario where the initiator LSR knows that there is a LAG, with two LAG members, between TTL=n and TTL=n+1, and has the multipath information to traverse the two LAG member links. The initiator LSR sends two MPLS echo request messages to traverse the two LAG member links at TTL=n+1: o Success case: * One MPLS echo request message reaches TTL=n+1 on an LAG member @@ -648,26 +648,26 @@ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSR Capability Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: LSR Capability TLV Where: - The Type is 2 octets in length and the value is TBD1. + The Type field is 2 octets in length and the value is TBD1. - The Length filed is 2 octets in length, and the value is 4. + The Length field is 2 octets in length, and the value is 4. - The LSR Capability Flags is 4 octets in length, this document - defines following flags: + The "LSR Capability Flags" field is 4 octets in length, this + document defines the following flags: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Must Be Zero (Reserved) |U|D| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This document defines two flags. The remaining flags MUST be set to zero when sending and ignored on receipt. Both the U and the D flag MUST be cleared in the MPLS echo request message when @@ -686,21 +686,21 @@ D Downstream LAG Info Accommodation An LSR sets this flag when the LSR is capable of describing LAG member links in the Local Interface Index Sub-TLV and the Multipath Data Sub-TLV in the Downstream Detailed Mapping TLV. 7. LAG Description Indicator Flag: G - This document defines a flag, the "G" flag (LAG Description + This document defines a new flag, the "G" flag (LAG Description Indicator), in the DS Flags field of the DDMAP TLV. The "G" flag in the MPLS echo request message indicates the request for detailed LAG information from the responder LSR. In the MPLS echo reply message, the "G" flag MUST be set if the DDMAP TLV describes a LAG interface. It MUST be cleared otherwise. The "G" flag is defined as below: The Bit Number is TBD5. @@ -932,81 +932,95 @@ M LAG Member Link Indicator When this flag is set, interface index described in this sub-TLV is a member of a LAG. Incoming Interface Index An Index assigned by the LSR to this interface. -11. Security Considerations +11. Rate Limiting On Echo Request/Reply Messages - This document extends LSP Traceroute mechanism to discover and - exercise L2 ECMP paths. As a result of supporting the code points - and procedures described in this document, additional processing are - required by initiator LSRs and responder LSRs, especially to compute - and handle the additional multipath information. Due to additional - processing, it is critical that proper security measures described in - [RFC8029] are followed. + For an LSP path, it may be over several LAGs. Each LAG may have many + member links. To exercise all the links, many Echo Request/Reply + messages will be sent in a short period. It's possible that those + messages may traverse a common path as a burst. Under some + circumstances this might cause congestion at the common path. To + avoid potential congestion, it is RECOMMENDED that implementations to + randomly delay the Echo Request and Reply messages at the Initiating + LSRs and Responder LSRs. - The LSP Traceroute allows an initiator LSR to discover the paths of - tested LSPs, providing detailed knowledge of the MPLS network. - Exposing such information to a malicious user is considered - dangerous. To prevent leakage of vital information to untrusted - users, a responder LSR MUST only accept MPLS echo request messages - from trusted sources via filtering source IP address field of - received MPLS echo request messages.[RFC8029] provides additional - recommendations to avoid attacks and recommendations to follow if an - operator desires to prevent tracing. +12. Security Considerations -12. IANA Considerations + This document extends LSP Traceroute mechanism [RFC8029] to discover + and exercise L2 ECMP paths to determine problematic member link(s) of + a LAG. These on-demand diagnostic mechanisms are used by an operator + within an MPLS control domain. -12.1. LSR Capability TLV + [RFC8029] reviews the possible attacks and approaches to mitigate + possible threats when using these mechanisms. + + To prevent leakage of vital information to untrusted users, a + responder LSR MUST only accept MPLS echo request messages from + designated trusted sources via filtering source IP address field of + received MPLS echo request messages. As noted in [RFC8029], spoofing + attacks only have a small window of opportunity. If these messages + are indeed hijacked (non-delivery) by an intermediate node, the use + of these mechanisms will determine the data plane is not working (as + it should). Hijacking of a responder node such that it provides a + legitimate reply would involve compromising the node itself and the + MPLS control domain. [RFC5920] provides additional MPLS network-wide + operation recommendations to avoid attacks and recommendations to + follow. + +13. IANA Considerations + +13.1. LSR Capability TLV The IANA is requested to assign new value TBD1 for LSR Capability TLV from the "Multiprotocol Label Switching Architecture (MPLS) Label Switched Paths (LSPs) Ping Parameters - TLVs" registry. Value Meaning Reference ----- ------- --------- TBD1 LSR Capability TLV this document -12.1.1. LSR Capability Flags +13.1.1. LSR Capability Flags The IANA is requested to create and maintain a registry entitled "LSR Capability Flags" with following registration procedures: Registry Name: LAG Interface Info Flags Bit number Name Reference ---------- ---------------------------------------- --------- 31 D: Downstream LAG Info Accommodation this document 30 U: Upstream LAG Info Accommodation this document 0-29 Unassigned Assignments of LSR Capability Flags are via Standards Action [RFC8126]. -12.2. Local Interface Index Sub-TLV +13.2. Local Interface Index Sub-TLV The IANA is requested to assign new value TBD2 (from the range 4-31743) for the Local Interface Index Sub-TLV from the "Multiprotocol Label Switching Architecture (MPLS) Label Switched Paths (LSPs) Ping Parameters - TLVs" registry, "Sub-TLVs for TLV Types 20" sub-registry. Value Meaning Reference ----- ------- --------- TBD2 Local Interface Index Sub-TLV this document -12.2.1. Interface Index Flags +13.2.1. Interface Index Flags The IANA is requested to create and maintain a registry entitled "Interface Index Flags" with following registration procedures: Registry Name: Interface Index Flags Bit number Name Reference ---------- ---------------------------------------- --------- 15 M: LAG Member Link Indicator this document 0-14 Unassigned @@ -1019,44 +1033,44 @@ o The Local Interface Index Sub-TLV which may be present in the "Downstream Detailed Mapping" TLV. o The Remote Interface Index Sub-TLV which may be present in the "Downstream Detailed Mapping" TLV. o The Incoming Interface Index Sub-TLV which may be present in the "Detailed Interface and Label Stack" TLV. -12.3. Remote Interface Index Sub-TLV +13.3. Remote Interface Index Sub-TLV The IANA is requested to assign new value TBD3 (from the range 32768-49161) for the Remote Interface Index Sub-TLV from the "Multiprotocol Label Switching Architecture (MPLS) Label Switched Paths (LSPs) Ping Parameters - TLVs" registry, "Sub-TLVs for TLV Types 20" sub-registry. Value Meaning Reference ----- ------- --------- TBD3 Remote Interface Index Sub-TLV this document -12.4. Detailed Interface and Label Stack TLV +13.4. Detailed Interface and Label Stack TLV The IANA is requested to assign new value TBD4 for Detailed Interface and Label Stack TLV from the "Multiprotocol Label Switching Architecture (MPLS) Label Switched Paths (LSPs) Ping Parameters - TLVs" registry ([IANA-MPLS-LSP-PING]). Value Meaning Reference ----- ------- --------- TBD4 Detailed Interface and Label Stack TLV this document -12.4.1. Sub-TLVs for TLV Type TBD4 +13.4.1. Sub-TLVs for TLV Type TBD4 The IANA is requested to create and maintain a sub-registry entitled "Sub-TLVs for TLV Type TBD4" under "Multiprotocol Label Switching Architecture (MPLS) Label Switched Paths (LSPs) Ping Parameters - TLVs" registry. Initial values for this sub-registry, "Sub-TLVs for TLV Types TBD4", are described below. Sub-Type Name Reference @@ -1065,81 +1079,85 @@ 2 Incoming Interface Index this document 3-16383 Unassigned (mandatory TLVs) 16384-31743 Experimental 32768-49161 Unassigned (optional TLVs) 49162-64511 Experimental Assignments of Sub-Types in the mandatory and optional spaces are via Standards Action [RFC8126]. Assignments of Sub-Types in the experimental space is via Specification Required [RFC8126]. -12.5. DS Flags +13.5. DS Flags The IANA is requested to assign a new bit number from the "DS flags" sub-registry from the "Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters - TLVs" registry ([IANA-MPLS-LSP-PING]). Note: the "DS flags" sub-registry is created by [RFC8029]. Bit number Name Reference ---------- ---------------------------------------- --------- TBD5 G: LAG Description Indicator this document -13. Acknowledgements +14. Acknowledgements The authors would like to thank Nagendra Kumar, Sam Aldrin, for providing useful comments and suggestions. The authors would like to thank Loa Andersson for performing a detailed review and providing number of comments. The authors also would like to extend sincere thanks to the MPLS RT review members who took time to review and provide comments. The members are Eric Osborne, Mach Chen and Yimin Shen. The suggestion by Mach Chen to generalize and create the LSR Capability TLV was tremendously helpful for this document and likely for future documents extending the MPLS LSP Ping and Traceroute mechanism. The suggestion by Yimin Shen to create two separate validation procedures had a big impact to the contents of this document. -14. References +15. References -14.1. Normative References +15.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., Aldrin, S., and M. Chen, "Detecting Multiprotocol Label Switched (MPLS) Data-Plane Failures", RFC 8029, DOI 10.17487/RFC8029, March 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . -14.2. Informative References +15.2. Informative References [IANA-MPLS-LSP-PING] IANA, "Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters", . [IEEE802.1AX] IEEE Std. 802.1AX, "IEEE Standard for Local and metropolitan area networks - Link Aggregation", November 2008. + [RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS + Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010, + . + [RFC7439] George, W., Ed. and C. Pignataro, Ed., "Gap Analysis for Operating IPv6-Only MPLS Networks", RFC 7439, DOI 10.17487/RFC7439, January 2015, . [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, .