--- 1/draft-ietf-bfd-unsolicited-00.txt 2019-06-28 13:13:11.736839798 -0700 +++ 2/draft-ietf-bfd-unsolicited-01.txt 2019-06-28 13:13:11.848842630 -0700 @@ -1,56 +1,56 @@ Network Working Group E. Chen Internet-Draft N. Shen Intended status: Standards Track Cisco Systems -Expires: August 29, 2019 R. Raszuk +Expires: December 30, 2019 R. Raszuk Bloomberg LP R. Rahman Cisco Systems - February 25, 2019 + June 28, 2019 Unsolicited BFD for Sessionless Applications - draft-ietf-bfd-unsolicited-00 + draft-ietf-bfd-unsolicited-01 Abstract For operational simplification of "sessionless" applications using BFD, in this document we present procedures for "unsolicited BFD" that allow a BFD session to be initiated by only one side, and be established without explicit per-session configuration or registration by the other side (subject to certain per-interface or per-router policies). Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", - "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to - be interpreted as described in [RFC2119] only when they appear in all - upper case. They may also appear in lower or mixed case as English - words, without normative meaning. + "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and + "OPTIONAL" in this document are to be interpreted as described in BCP + 14 [RFC2119] [RFC8174] when, and only when, they appear in all + capitals, as shown here. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at 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 August 29, 2019. + This Internet-Draft will expire on December 30, 2019. Copyright Notice 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 @@ -62,24 +62,26 @@ Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Procedures for Unsolicited BFD . . . . . . . . . . . . . . . 3 3. YANG Data Model . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Unsolicited BFD Hierarchy . . . . . . . . . . . . . . . . 4 3.2. Unsolicited BFD Module . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 - 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 6.1. Normative References . . . . . . . . . . . . . . . . . . 9 - 6.2. Informative References . . . . . . . . . . . . . . . . . 10 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 + 5.1. BFD Protocol Security Considerations . . . . . . . . . . 9 + 5.2. YANG Module Security Considerations . . . . . . . . . . . 9 + 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 + 6.1. Normative References . . . . . . . . . . . . . . . . . . 10 + 6.2. Informative References . . . . . . . . . . . . . . . . . 11 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 1. Introduction The current implementation and deployment practice for BFD ([RFC5880] and [RFC5881]) usually requires BFD sessions be explicitly configured or registered on both sides. This requirement is not an issue when an application like BGP [RFC4271] has the concept of a "session" that involves both sides for its establishment. However, this requirement can be operationally challenging when the prerequisite "session" does not naturally exist between two endpoints in an application. @@ -166,51 +169,51 @@ registered client for the BFD session. 3. YANG Data Model This section extends the YANG data model for BFD [I-D.ietf-bfd-yang] to cover the unsolicited BFD. 3.1. Unsolicited BFD Hierarchy module: ietf-bfd-unsolicited augment /rt:routing/rt:control-plane-protocols - /rt:control-plane-protocol/bfd:bfd: + /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh: +--rw unsolicited {bfd-unsol:unsolicited-params-global}? - +--rw allow? boolean + +--rw enable? boolean +--rw local-multiplier? multiplier +--rw (interval-config-type)? +--:(tx-rx-intervals) | +--rw desired-min-tx-interval? uint32 | +--rw required-min-rx-interval? uint32 +--:(single-interval) {single-minimum-interval}? +--rw min-interval? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh /bfd-ip-sh:interfaces: +--rw unsolicited {bfd-unsol:unsolicited-params-per-interface}? - +--rw allow? boolean + +--rw enable? boolean +--rw local-multiplier? multiplier +--rw (interval-config-type)? +--:(tx-rx-intervals) | +--rw desired-min-tx-interval? uint32 | +--rw required-min-rx-interval? uint32 +--:(single-interval) {single-minimum-interval}? +--rw min-interval? uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh /bfd-ip-sh:sessions/bfd-ip-sh:session: +--ro unsolicited +--ro role? bfd-unsol:unsolicited-role 3.2. Unsolicited BFD Module - file "ietf-bfd-unsolicited@ 2018-10-27.yang" + file "ietf-bfd-unsolicited@2019-06-26.yang" module ietf-bfd-unsolicited { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited"; prefix "bfd-unsol"; // RFC Ed.: replace occurences of XXXX/YYYY with actual RFC numbers @@ -261,21 +264,21 @@ to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; reference "RFC YYYY"; - revision 2018-10-27 { + revision 2019-06-26 { description "Initial revision."; reference "RFC YYYY: A YANG data model for BFD unsolicited"; } /* * Feature definitions */ feature unsolicited-params-global { description "This feature indicates that the server supports global @@ -300,50 +303,51 @@ description "Passive role"; } } description "Unsolicited role"; } /* * Augments */ augment "/rt:routing/rt:control-plane-protocols/" - + "rt:control-plane-protocol/bfd:bfd" { + + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh" { description "Augmentation for BFD unsolicited parameters"; container unsolicited { if-feature bfd-unsol:unsolicited-params-global; description "BFD unsolicited top level container"; - leaf allow { + leaf enable { type boolean; default false; - description "Allow BFD unsolicited globally."; + description + "Enable BFD unsolicited globally for IP single-hop."; } uses bfd-types:base-cfg-parms; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/" + "bfd-ip-sh:interfaces" { description "Augmentation for BFD unsolicited on IP single-hop interface"; container unsolicited { if-feature bfd-unsol:unsolicited-params-per-interface; description "BFD IP single-hop interface unsolicited top level container"; - leaf allow { + leaf enable { type boolean; default false; - description "Allow BFD unsolicited on this interface."; + description "Enable BFD unsolicited on this interface."; } uses bfd-types:base-cfg-parms; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/" + "bfd-ip-sh:sessions/bfd-ip-sh:session" { description "Augmentation for BFD unsolicited on IP single-hop session"; @@ -360,74 +364,155 @@ } 4. IANA Considerations This documents makes no IANA requests. 5. Security Considerations +5.1. BFD Protocol Security Considerations + The same security considerations as those described in [RFC5880] and [RFC5881] apply to this document. With "unsolicited BFD" there is potential risk for excessive resource usage by BFD from "unexpected" remote systems. To mitigate such risks, the following measures are RECOMMENDED: o Limit the feature to specific interfaces, and to a single-hop BFD with "TTL=255" [RFC5082]. In addition make sure the source address of an incoming BFD packet belongs to the subnet of the interface from which the BFD packet is received. o Apply "access control" to allow BFD packets only from certain subnets or hosts. o Deploy the feature only in certain "trustworthy" environment, e.g., at an IXP, or between a provider and its customers. o Adjust BFD parameters as needed for the particular deployment and scale. o Use BFD authentication. +5.2. YANG Module Security Considerations + + The YANG module specified in this document defines a schema for data + that is designed to be accessed via network management protocols such + as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer + is the secure transport layer, and the mandatory-to-implement secure + transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer + is HTTPS, and the mandatory-to-implement secure transport is TLS + [RFC5246]. + + The NETCONF access control model [RFC6536] provides the means to + restrict access for particular NETCONF or RESTCONF users to a + preconfigured subset of all available NETCONF or RESTCONF protocol + operations and content. + + There are a number of data nodes defined in this YANG module that are + writable/creatable/deletable (i.e., config true, which is the + default). These data nodes may be considered sensitive or vulnerable + in some network environments. Write operations (e.g., edit-config) + to these data nodes without proper protection can have a negative + effect on network operations. These are the subtrees and data nodes + and their sensitivity/vulnerability: + + /routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh + /unsolicited: + + o data node "enable" enables creation of unsolicited BFD IP single- + hop sessions globally, i.e. on all interfaces. See Section 5.1. + o data nodes local-multiplier, desired-min-tx-interval, required- + min-rx-interval and min-interval all impact the parameters of the + unsolicited BFD IP single-hop sessions. + + /routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh + /interfaces/interface/unsolicited: + + o data node "enable" enables creation of unsolicited BFD IP single- + hop sessions on a specific interface. See Section 5.1. + o data nodes local-multiplier, desired-min-tx-interval, required- + min-rx-interval and min-interval all impact the parameters of the + unsolicited BFD IP single-hop sessions on the interface. + + Some of the readable data nodes in this YANG module may be considered + sensitive or vulnerable in some network environments. It is thus + important to control read access (e.g., via get, get-config, or + notification) to these data nodes. These are the subtrees and data + nodes and their sensitivity/vulnerability: + + /routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh + /sessions/session/unsolicited: access to this information discloses + the role of the local system in the creation of the unsolicited BFD + session. + 6. References 6.1. Normative References [I-D.ietf-bfd-yang] Rahman, R., Zheng, L., Jethanandani, M., Networks, J., and G. Mirsky, "YANG Data Model for Bidirectional Forwarding Detection (BFD)", draft-ietf-bfd-yang-17 (work in progress), August 2018. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C. Pignataro, "The Generalized TTL Security Mechanism (GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007, . + [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security + (TLS) Protocol Version 1.2", RFC 5246, + DOI 10.17487/RFC5246, August 2008, + . + [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, . [RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, DOI 10.17487/RFC5881, June 2010, . + [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., + and A. Bierman, Ed., "Network Configuration Protocol + (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, + . + + [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure + Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, + . + + [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration + Protocol (NETCONF) Access Control Model", RFC 6536, + DOI 10.17487/RFC6536, March 2012, + . + + [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF + Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, + . + + [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC + 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, + May 2017, . + 6.2. Informative References [I-D.ietf-idr-rs-bfd] Bush, R., Haas, J., Scudder, J., Nipper, A., and C. Dietzel, "Making Route Servers Aware of Data Link Failures - at IXPs", draft-ietf-idr-rs-bfd-06 (work in progress), - October 2018. + at IXPs", draft-ietf-idr-rs-bfd-07 (work in progress), + March 2019. [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006, . [RFC7880] Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S. Pallagatti, "Seamless Bidirectional Forwarding Detection (S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016, .