rfc9468.original   rfc9468.txt 
Network Working Group E. Chen Internet Engineering Task Force (IETF) E. Chen
Internet-Draft Palo Alto Networks Request for Comments: 9468 Palo Alto Networks
Intended status: Standards Track N. Shen Category: Standards Track N. Shen
Expires: 29 October 2023 Zededa ISSN: 2070-1721 Zededa
R. Raszuk R. Raszuk
Arrcus Arrcus
R. Rahman R. Rahman
Graphiant Equinix
27 April 2023 August 2023
Unsolicited BFD for Sessionless Applications Unsolicited Bidirectional Forwarding Detection (BFD) for Sessionless
draft-ietf-bfd-unsolicited-16 Applications
Abstract Abstract
For operational simplification of "sessionless" applications using For operational simplification of "sessionless" applications using
Bidirectional Forwarding Detection (BFD), in this document we present Bidirectional Forwarding Detection (BFD), in this document, we
procedures for "unsolicited BFD" that allow a BFD session to be present procedures for "unsolicited BFD" that allow a BFD session to
initiated by only one side, and established without explicit per- be initiated by only one side and established without explicit per-
session configuration or registration by the other side (subject to session configuration or registration by the other side (subject to
certain per-interface or global policies). certain per-interface or global policies).
We also introduce a new YANG module to configure and manage We also introduce a new YANG module to configure and manage
"unsolicited BFD". The YANG module in this document is based on YANG "unsolicited BFD". The YANG module in this document is based on YANG
1.1 as defined in RFC 7950 and conforms to the Network Management 1.1, as defined in RFC 7950, and conforms to the Network Management
Datastore Architecture (NMDA) as described in RFC 8342. This Datastore Architecture (NMDA), as described in RFC 8342. This
document augments RFC 9314. document augments RFC 9314.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"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 Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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-
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 29 October 2023. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9468.
Copyright Notice Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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in the Revised BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Procedures for Unsolicited BFD . . . . . . . . . . . . . . . 4 1.1. Requirements Language
3. State Variables . . . . . . . . . . . . . . . . . . . . . . . 5 2. Procedures for Unsolicited BFD
4. YANG Data Model . . . . . . . . . . . . . . . . . . . . . . . 5 3. State Variables
4.1. Unsolicited BFD Hierarchy . . . . . . . . . . . . . . . . 5 4. YANG Data Model
4.2. Unsolicited BFD Module . . . . . . . . . . . . . . . . . 6 4.1. Unsolicited BFD Hierarchy
4.3. Data Model Example . . . . . . . . . . . . . . . . . . . 11 4.2. Unsolicited BFD Module
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 4.3. Data Model Example
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 5. IANA Considerations
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 6. Security Considerations
7.1. BFD Protocol Security Considerations . . . . . . . . . . 13 6.1. BFD Protocol Security Considerations
7.2. BFD Protocol Authentication Considerations . . . . . . . 14 6.2. BFD Protocol Authentication Considerations
7.3. YANG Module Security Considerations . . . . . . . . . . . 14 6.3. YANG Module Security Considerations
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 7. References
8.1. Normative References . . . . . . . . . . . . . . . . . . 15 7.1. Normative References
8.2. Informative References . . . . . . . . . . . . . . . . . 17 7.2. Informative References
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 Acknowledgments
Authors' Addresses
1. Introduction 1. Introduction
The current implementation and deployment practice for BFD ([RFC5880] The current implementation and deployment practice for BFD ([RFC5880]
and [RFC5881]) usually requires BFD sessions be explicitly configured and [RFC5881]) usually requires that BFD sessions be explicitly
or registered on both sides. This requirement is not an issue when configured or registered on both sides. This requirement is not an
an application like BGP [RFC4271] has the concept of a "session" that issue when an application like BGP [RFC4271] has the concept of a
involves both sides for its establishment. However, this requirement "session" that involves both sides for its establishment. However,
can be operationally challenging when the prerequisite "session" does this requirement can be operationally challenging when the
not naturally exist between two endpoints in an application. prerequisite "session" does not naturally exist between two endpoints
Simultaneous configuration and coordination may be required on both in an application. Simultaneous configuration and coordination may
sides for BFD to take effect. For example: be required on both sides for BFD to take effect. For example:
* When BFD is used to keep track of the "liveness" of the nexthop of * When BFD is used to keep track of the "liveness" of the next hop
static routes. Although only one side may need the BFD of static routes. Although only one side may need the BFD
functionality, currently both sides need to be involved in functionality, currently, both sides need to be involved in
specific configuration and coordination and in some cases static specific configuration and coordination, and in some cases, static
routes are created unnecessarily just for BFD. routes are created unnecessarily just for BFD.
* When BFD is used to keep track of the "liveness" of the third-pary
nexthop of BGP routes received from the Route Server [RFC7947] at
an Internet Exchange Point (IXP). As the third-party nexthop is
different from the peering address of the Route Server, for BFD to
work, currently two routers peering with the Route Server need to
have routes and nexthops from each other (although indirectly via
the Route Server).
Clearly it is beneficial and desirable to reduce or eliminate * When BFD is used to keep track of the "liveness" of the third-
party next hop of BGP routes received from the Route Server
[RFC7947] at an Internet Exchange Point (IXP). As the third-party
next hop is different from the peering address of the Route
Server, for BFD to work, currently, two routers peering with the
Route Server need to have routes and next hops from each other
(although indirectly via the Route Server).
Clearly, it is beneficial and desirable to reduce or eliminate
unnecessary configurations and coordination in these "sessionless" unnecessary configurations and coordination in these "sessionless"
applications using BFD. applications using BFD.
In this document we present procedures for "unsolicited BFD" that In this document, we present procedures for "unsolicited BFD" that
allow a BFD session to be initiated by only one side, and established allow a BFD session to be initiated by only one side and established
without explicit per-session configuration or registration by the without explicit per-session configuration or registration by the
other side (subject to certain per-interface or global policies). other side (subject to certain per-interface or global policies).
Unsolicited BFD impacts only the initiation of BFD sessions. There Unsolicited BFD impacts only the initiation of BFD sessions. There
is no change to all the other procedures specified in [RFC5880] such is no change to all the other procedures specified in [RFC5880], such
as, but not limited to, the Echo function and Demand mode. as, but not limited to, the Echo function and Demand mode.
With "unsolicited BFD" there is potential risk for excessive resource With "unsolicited BFD", there is potential risk for excessive
usage by BFD from "unexpected" remote systems. To mitigate such resource usage by BFD from "unexpected" remote systems. To mitigate
risks, several mechanisms are recommended in the Security such risks, several mechanisms are recommended in the Security
Considerations section. Considerations section.
The procedure described in this document could be applied to BFD for The procedure described in this document could be applied to BFD for
Multihop paths [RFC5883]. However, because of security risks, this multihop paths [RFC5883]. However, because of security risks, this
document applies only to BFD for single IP hops [RFC5881]. document applies only to BFD for single IP hops [RFC5881].
Compared to the "Seamless BFD" [RFC7880], this proposal involves only Compared to the "Seamless BFD" [RFC7880], this proposal involves only
minor procedural enhancements to the widely deployed BFD itself. minor procedural enhancements to the widely deployed BFD itself.
Thus, we believe that this proposal is inherently simpler in the Thus, we believe that this proposal is inherently simpler in the
protocol itself and deployment. As an example, it does not require protocol itself and deployment. As an example, it does not require
the exchange of BFD discriminators over an out-of-band channel before the exchange of BFD discriminators over an out-of-band channel before
BFD session bring-up. BFD session bring-up.
When BGP Add-Path [RFC7911] is deployed at an IXP using a Route When BGP ADD-PATH [RFC7911] is deployed at an IXP using a Route
Server, multiple BGP paths (when they exist) can be made available to Server, multiple BGP paths (when they exist) can be made available to
the clients of the Route Server as described in [RFC7947]. the clients of the Route Server, as described in [RFC7947].
Unsolicited BFD can be used by BGP route selection's Route Unsolicited BFD can be used by BGP route selection's route
Resolvability Condition Section 9.1.2.1 of [RFC4271] to exclude resolvability condition (Section 9.1.2.1 of [RFC4271]) to exclude
routes where the NEXT_HOP is not reachable using the procedures routes where the NEXT_HOP is not reachable using the procedures
specified in this document. specified in this document.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"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.
2. Procedures for Unsolicited BFD 2. Procedures for Unsolicited BFD
With "unsolicited BFD", one side takes the "Active role" and the With "unsolicited BFD", one side takes the "Active role" and the
other side takes only the "Passive role" as described in [RFC5880], other side takes the "Passive role", as described in [RFC5880],
section 6.1. Section 6.1.
Passive unsolicited BFD support MUST be disabled by default, and MUST Passive unsolicited BFD support MUST be disabled by default and MUST
require explicit configuration to be enabled. On the passive side, require explicit configuration to be enabled. On the passive side,
the following BFD parameters, from [RFC5880] section 6.8.1 SHOULD be the following BFD parameters, from [RFC5880], Section 6.8.1, SHOULD
configurable: be configurable:
* bfd.DesiredMinTxInterval * bfd.DesiredMinTxInterval
* bfd.RequiredMinRxInterval * bfd.RequiredMinRxInterval
* bfd.DetectMult * bfd.DetectMult
The passive side MAY also choose to use the values of the parameters The passive side MAY also choose to use the values of the parameters
above that the active side uses in its BFD Control packets. However, listed above that the active side uses in its BFD Control packets.
the bfd.LocalDiscr value MUST be selected by the passive side to However, the bfd.LocalDiscr value MUST be selected by the passive
allow multiple unsolicited BFD sessions. side to allow multiple unsolicited BFD sessions.
The active side starts sending the BFD Control packets as specified The active side starts sending the BFD Control packets, as specified
in [RFC5880]. The passive side does not send BFD Control packets in [RFC5880]. The passive side does not send BFD Control packets
initially, it sends BFD Control packets only after it has received initially; it sends BFD Control packets only after it has received
BFD Control packets from the active side. BFD Control packets from the active side.
When the passive side receives a BFD Control packet from the active When the passive side receives a BFD Control packet from the active
side with 0 as "Your Discriminator" and does not find an existing BFD side with 0 as "Your Discriminator" and does not find an existing BFD
session, the passive side SHOULD create a matching BFD session toward session, the passive side SHOULD create a matching BFD session toward
the active side, unless not permitted by local configuration or the active side, unless not permitted by local configuration or
policy. policy.
When the passive side receives an incoming BFD Control packet on a When the passive side receives an incoming BFD Control packet on a
numbered interface, the source address of that packet MUST belong to numbered interface, the source address of that packet MUST belong to
the subnet of the interface on which the BFD packet is received, else the subnet of the interface on which the BFD packet is received, else
the BFD control packet MUST NOT be processed. the BFD Control packet MUST NOT be processed.
The passive side MUST then start sending BFD Control packets and The passive side MUST then start sending BFD Control packets and
perform the necessary procedure for bringing up, maintaining and perform the necessary procedure for bringing up, maintaining, and
tearing down the BFD session. If the BFD session fails to get tearing down the BFD session. If the BFD session fails to get
established within a certain amount of time (which is implementation established within a certain amount of time (which is implementation
specific but has to be at least equal to the local failure detection specific but has to be at least equal to the local failure detection
time), or if an established BFD session goes down, the passive side time) or if an established BFD session goes down, the passive side
MUST stop sending BFD Control packets and SHOULD delete the BFD MUST stop sending BFD Control packets and SHOULD delete the BFD
session created until BFD Control packets are initiated by the active session created until BFD Control packets are initiated by the active
side again. side again.
When an Unsolicited BFD session goes down, an implementation may When an unsolicited BFD session goes down, an implementation may
retain the session state for a period of time. Retaining this state retain the session state for a period of time. Retaining this state
can be useful for operational purposes. can be useful for operational purposes.
3. State Variables 3. State Variables
This document defines a new state variable called Role. This document defines a new state variable called Role:
bfd.Role bfd.Role
The role of the local system during BFD session initialization, as This is the role of the local system during BFD session
per [RFC5880], section 6.1. Possible values are Active or Passive. initialization, as per [RFC5880], Section 6.1. Possible values are
Active or Passive.
4. YANG Data Model 4. YANG Data Model
This section extends the YANG data model for BFD [RFC9314] to cover This section extends the YANG data model for BFD [RFC9314] to cover
unsolicited BFD. The new module imports [RFC8349] since the "bfd" unsolicited BFD. The new module imports the YANG modules described
container in [RFC9314] is under "control-plane-protocol". The YANG in [RFC8349] since the "bfd" container in [RFC9314] is under
module in this document conforms to the Network Management Datastore "control-plane-protocol". The YANG module in this document conforms
Architecture (NMDA) [RFC8342]. to the Network Management Datastore Architecture (NMDA) [RFC8342].
4.1. Unsolicited BFD Hierarchy 4.1. Unsolicited BFD Hierarchy
Configuration for unsolicited BFD parameters for IP single-hop Configuration for unsolicited BFD parameters for IP single-hop
sessions can be done at 2 levels: sessions can be done at 2 levels:
* Globally, i.e. for all interfaces. * globally, i.e., for all interfaces
* For specific interfaces. This requires support for the
"unsolicited-params-per-interface" feature. * for specific interfaces (this requires support for the
"unsolicited-params-per-interface" feature)
If configuration exists at both levels, per-interface configuration If configuration exists at both levels, per-interface configuration
takes precedence over global configuration. takes precedence over global configuration.
For operational data, a new "role" leaf node has been added for BFD For operational data, a new "role" leaf node has been added for BFD
IP single-hop sessions. IP single-hop sessions.
The tree diagram below uses the graphical representation of data The tree diagram below uses the graphical representation of data
models, as defined in [RFC8340]. models, as defined in [RFC8340].
module: ietf-bfd-unsolicited module: ietf-bfd-unsolicited
augment /rt:routing/rt:control-plane-protocols augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh: /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh:
+--rw unsolicited? +--rw unsolicited?
+--rw local-multiplier? multiplier +--rw local-multiplier? multiplier
+--rw (interval-config-type)? +--rw (interval-config-type)?
+--:(tx-rx-intervals) +--:(tx-rx-intervals)
| +--rw desired-min-tx-interval? uint32 | +--rw desired-min-tx-interval? uint32
| +--rw required-min-rx-interval? uint32 | +--rw required-min-rx-interval? uint32
+--:(single-interval) {single-minimum-interval}? +--:(single-interval) {single-minimum-interval}?
+--rw min-interval? uint32 +--rw min-interval? uint32
augment /rt:routing/rt:control-plane-protocols augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh
/bfd-ip-sh:interfaces: /bfd-ip-sh:interfaces:
+--rw unsolicited +--rw unsolicited
+--rw enabled? boolean +--rw enabled? boolean
+--rw local-multiplier? bfd-types:multiplier {bfd-unsol:unsolicited-params-per-interface}? +--rw local-multiplier?
+--rw (interval-config-type)? {bfd-unsol:unsolicited-params-per-interface}? bfd-types:multiplier
+--:(tx-rx-intervals) {bfd-unsol:unsolicited-params-per-interface}?
| +--rw desired-min-tx-interval? uint32 +--rw (interval-config-type)?
| +--rw required-min-rx-interval? uint32 {bfd-unsol:unsolicited-params-per-interface}?
+--:(single-interval) {bfd-types:single-minimum-interval}? +--:(tx-rx-intervals)
+--rw min-interval? uint32 | +--rw desired-min-tx-interval? uint32
augment /rt:routing/rt:control-plane-protocols | +--rw required-min-rx-interval? uint32
/rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh +--:(single-interval) {bfd-types:single-minimum-interval}?
/bfd-ip-sh:sessions/bfd-ip-sh:session: +--rw min-interval? uint32
+--ro role? bfd-unsol:role 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 role? bfd-unsol:role
4.2. Unsolicited BFD Module 4.2. Unsolicited BFD Module
<CODE BEGINS> file "ietf-bfd-unsolicited@2023-04-22.yang" <CODE BEGINS> file "ietf-bfd-unsolicited@2023-08-16.yang"
module ietf-bfd-unsolicited { module ietf-bfd-unsolicited {
yang-version 1.1; yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited"; namespace "urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited";
prefix "bfd-unsol"; prefix bfd-unsol;
// RFC Ed.: replace occurences of YYYY with actual RFC numbers
// and remove this note
import ietf-bfd-types { import ietf-bfd-types {
prefix "bfd-types"; prefix bfd-types;
reference reference
"RFC 9314: YANG Data Model for Bidirectional Forwarding "RFC 9314: YANG Data Model for Bidirectional Forwarding
Detection (BFD)"; Detection (BFD)";
} }
import ietf-bfd { import ietf-bfd {
prefix "bfd"; prefix bfd;
reference reference
"RFC 9314: YANG Data Model for Bidirectional Forwarding "RFC 9314: YANG Data Model for Bidirectional Forwarding
Detection (BFD)"; Detection (BFD)";
} }
import ietf-bfd-ip-sh { import ietf-bfd-ip-sh {
prefix "bfd-ip-sh"; prefix bfd-ip-sh;
reference reference
"RFC 9314: YANG Data Model for Bidirectional Forwarding "RFC 9314: YANG Data Model for Bidirectional Forwarding
Detection (BFD)"; Detection (BFD)";
} }
import ietf-routing { import ietf-routing {
prefix "rt"; prefix rt;
reference reference
"RFC 8349: A YANG Data Model for Routing Management "RFC 8349: A YANG Data Model for Routing Management
(NMDA version)"; (NMDA Version)";
} }
organization "IETF BFD Working Group"; organization
"IETF BFD Working Group";
contact contact
"WG Web: <https://datatracker.ietf.org/wg/bfd/> "WG Web: <https://datatracker.ietf.org/wg/bfd/>
WG List: <rtg-bfd@ietf.org> WG List: <rtg-bfd@ietf.org>
Editors: Enke Chen (enchen@paloaltonetworks.com), Editors: Enke Chen (enchen@paloaltonetworks.com),
Naiming Shen (naiming@zededa.com), Naiming Shen (naiming@zededa.com),
Robert Raszuk (robert@raszuk.net), Robert Raszuk (robert@raszuk.net),
Reshad Rahman (reshad@yahoo.com)"; Reshad Rahman (reshad@yahoo.com)";
description description
"This module contains the YANG definition for BFD unsolicited "This module contains the YANG definition for unsolicited BFD,
as per RFC YYYY. as per RFC 9468.
Copyright (c) 2023 IETF Trust and the persons Copyright (c) 2023 IETF Trust and the persons
identified as authors of the code. All rights reserved. identified as authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject without modification, is permitted pursuant to, and subject
to the license terms contained in, the Revised BSD License to the license terms contained in, the Revised BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents Relating to IETF Documents
(http://trustee.ietf.org/license-info). (http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC YYYY; see This version of this YANG module is part of RFC 9468; see
the RFC itself for full legal notices."; the RFC itself for full legal notices.";
reference "RFC YYYY"; reference
"RFC 9468: Unsolicited Bidirectional Forwarding Detection
(BFD) for Sessionless Applications";
revision 2023-04-22 { revision 2023-08-16 {
description description
"Initial revision."; "Initial revision.";
reference reference
"RFC YYYY: Unsolicited BFD for Sessionless Applications."; "RFC 9468: Unsolicited Bidirectional Forwarding Detection (BFD)
for Sessionless Applications";
} }
/* /*
* Feature definitions * Feature definitions
*/ */
feature unsolicited-params-per-interface { feature unsolicited-params-per-interface {
description description
"This feature indicates that the server supports per-interface "This feature indicates that the server supports per-interface
parameters for unsolicited sessions."; parameters for unsolicited sessions.";
reference reference
"RFC YYYY: Unsolicited BFD for Sessionless Applications."; "RFC 9468: Unsolicited Bidirectional Forwarding Detection (BFD)
for Sessionless Applications";
} }
/* /*
* Type Definitions * Type Definitions
*/ */
identity role { identity role {
description description
"Base identity from which all roles are derived. "Base identity from which all roles are derived.
Role of local system during BFD session initialization."; Role of local system during BFD session initialization.";
} }
identity active { identity active {
base "bfd-unsol:role"; base bfd-unsol:role;
description "Active role"; description
"Active role.";
reference reference
"RFC5880: Bidirectional Forwarding Detection (BFD), "RFC 5880: Bidirectional Forwarding Detection (BFD),
Section 6.1"; Section 6.1";
} }
identity passive { identity passive {
base "bfd-unsol:role"; base bfd-unsol:role;
description "Passive role"; description
"Passive role.";
reference reference
"RFC5880: Bidirectional Forwarding Detection (BFD), "RFC 5880: Bidirectional Forwarding Detection (BFD),
Section 6.1"; Section 6.1";
} }
/* /*
* Augments * Augments
*/ */
augment "/rt:routing/rt:control-plane-protocols/"
+ "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh" {
description
"Augmentation for BFD unsolicited parameters";
container unsolicited {
description
"BFD IP single-hop unsolicited top level container";
uses bfd-types:base-cfg-parms;
}
}
augment "/rt:routing/rt:control-plane-protocols/" augment "/rt:routing/rt:control-plane-protocols/"
+ "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/" + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh" {
+ "bfd-ip-sh:interfaces" { description
description "Augmentation for unsolicited BFD parameters.";
"Augmentation for BFD unsolicited on IP single-hop interface"; container unsolicited {
container unsolicited { description
description "BFD IP single-hop unsolicited top-level container.";
"BFD IP single-hop interface unsolicited top level uses bfd-types:base-cfg-parms;
container"; }
leaf enabled { }
type boolean;
default false;
description
"BFD unsolicited enabled on this interface.";
}
/*
* The following is the same as bfd-types:base-cfg-parms, but
* without default values (for inheritance)
*/
leaf local-multiplier {
if-feature bfd-unsol:unsolicited-params-per-interface;
type bfd-types:multiplier;
description
"Multiplier transmitted by the local system. Defaults to
../../unsolicited/local-multiplier.
A multiplier configured under an interface takes precedence
over the mulitiplier configured at the global level.";
}
choice interval-config-type {
if-feature bfd-unsol:unsolicited-params-per-interface;
description
"Two interval values or one value used for both transmit and
receive. Defaults to ../../unsolicited/interval-config-type.
An interval configured under an interface takes precedence
over any interval configured at the global level.";
case tx-rx-intervals {
leaf desired-min-tx-interval {
type uint32;
units "microseconds";
description
"Desired minimum transmit interval of control packets.";
}
leaf required-min-rx-interval {
type uint32;
units "microseconds";
description
"Required minimum receive interval of control packets.";
}
}
case single-interval {
if-feature "bfd-types:single-minimum-interval";
leaf min-interval {
type uint32;
units "microseconds";
description
"Desired minimum transmit interval and required
minimum receive interval of control packets.";
}
}
}
}
}
augment "/rt:routing/rt:control-plane-protocols/" augment "/rt:routing/rt:control-plane-protocols/"
+ "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/" + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/"
+ "bfd-ip-sh:sessions/bfd-ip-sh:session" { + "bfd-ip-sh:interfaces" {
description description
"Augmentation for BFD unsolicited on IP single-hop session"; "Augmentation for unsolicited BFD on IP single-hop
leaf role { interface.";
type identityref { container unsolicited {
base "bfd-unsol:role"; description
"BFD IP single-hop interface unsolicited top-level
container.";
leaf enabled {
type boolean;
default "false";
description
"Unsolicited BFD is enabled on this interface.";
}
/*
* The following is the same as bfd-types:base-cfg-parms, but
* without default values (for inheritance)
*/
leaf local-multiplier {
if-feature "bfd-unsol:unsolicited-params-per-interface";
type bfd-types:multiplier;
description
"Multiplier transmitted by the local system. Defaults to
../../unsolicited/local-multiplier.
A multiplier configured under an interface takes
precedence over the multiplier configured at the global
level.";
}
choice interval-config-type {
if-feature "bfd-unsol:unsolicited-params-per-interface";
description
"Two interval values or one value used for both transmit
and receive. Defaults to
../../unsolicited/interval-config-type. An interval
configured under an interface takes precedence over any
interval configured at the global level.";
case tx-rx-intervals {
leaf desired-min-tx-interval {
type uint32;
units "microseconds";
description
"Desired minimum transmit interval of control
packets.";
}
leaf required-min-rx-interval {
type uint32;
units "microseconds";
description
"Required minimum receive interval of control
packets.";
}
}
case single-interval {
if-feature "bfd-types:single-minimum-interval";
leaf min-interval {
type uint32;
units "microseconds";
description
"Desired minimum transmit interval and required
minimum receive interval of control packets.";
}
} }
config false;
description "Role.";
} }
}
} }
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 unsolicited BFD on IP single-hop session.";
leaf role {
type identityref {
base bfd-unsol:role;
}
config false;
description
"Role.";
}
}
} }
<CODE ENDS> <CODE ENDS>
4.3. Data Model Example 4.3. Data Model Example
This section shows an example on how to configure the passive end of This section shows an example on how to configure the passive end of
unsolicited BFD: unsolicited BFD:
* We have global BFD IP single-hop unsolicited configuration with a * We have global BFD IP single-hop unsolicited configuration with a
local-multiplier of 2 and min-interval at 50ms local-multiplier of 2 and min-interval at 50 ms.
* BFD IP single-hop unsolicited is enabled on interface eth0, with a
local-multiplier of 3 and min-interval at 250 ms * BFD IP single-hop unsolicited is enabled on interface eth0 with a
local-multiplier of 3 and min-interval at 250 ms.
* BFD IP single-hop unsolicited is enabled on interface eth1. Since * BFD IP single-hop unsolicited is enabled on interface eth1. Since
there is no parameter configuration for eth1, it inherits from the there is no parameter configuration for eth1, it inherits from the
global configuration. global configuration.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"> <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces">
<interface> <interface>
<name>eth0</name> <name>eth0</name>
<type <type
xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">ianaift:ethernetCsmacd</type> xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
</interface> ianaift:ethernetCsmacd</type>
<interface> </interface>
<name>eth1</name> <interface>
<type <name>eth1</name>
xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">ianaift:ethernetCsmacd</type> <type
</interface> xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
</interfaces> ianaift:ethernetCsmacd</type>
<routing xmlns="urn:ietf:params:xml:ns:yang:ietf-routing"> </interface>
<control-plane-protocols> </interfaces>
<control-plane-protocol> <routing xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">
<type <control-plane-protocols>
xmlns:bfd-types="urn:ietf:params:xml:ns:yang:ietf-bfd-types">bfd-types:bfdv1</type> <control-plane-protocol>
<name>name:BFD</name> <type xmlns:bfd-types=
<bfd xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd"> "urn:ietf:params:xml:ns:yang:ietf-bfd-types">
<ip-sh xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd-ip-sh"> bfd-types:bfdv1</type>
<unsolicited> <name>name:BFD</name>
<local-multiplier>2</local-multiplier> <bfd xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd">
<min-interval>50000</min-interval> <ip-sh xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd-ip-sh">
</unsolicited> <unsolicited>
<interfaces> <local-multiplier>2</local-multiplier>
<interface>eth0</interface> <min-interval>50000</min-interval>
<unsolicited> </unsolicited>
<enabled>true</enabled> <interfaces>
<local-multiplier>3</local-multiplier> <interface>eth0</interface>
<min-interval>250000</min-interval> <unsolicited>
</unsolicited> <enabled>true</enabled>
</interfaces> <local-multiplier>3</local-multiplier>
<interfaces> <min-interval>250000</min-interval>
<interface>eth1</interface> </unsolicited>
<unsolicited> </interfaces>
<enabled>true</enabled> <interfaces>
</unsolicited> <interface>eth1</interface>
</interfaces> <unsolicited>
</ip-sh> <enabled>true</enabled>
</bfd> </unsolicited>
</control-plane-protocol> </interfaces>
</control-plane-protocols> </ip-sh>
</routing> </bfd>
</config> </control-plane-protocol>
5. IANA Considerations </control-plane-protocols>
</routing>
This document registers the following namespace URI in the "IETF XML </config>
Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited 5. IANA Considerations
Registrant Contact: The IESG. IANA has registered the following namespace URI in the "ns"
subregistry within the "IETF XML Registry" [RFC3688]:
XML: N/A; the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
This document registers the following YANG module in the "YANG Module IANA has registered the following YANG module in the "YANG Module
Names" registry [RFC6020]: Names" registry [RFC6020]:
Name: ietf-bfd-unsolicited Name: ietf-bfd-unsolicited
Maintained by IANA: N
Namespace: urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited Namespace: urn:ietf:params:xml:ns:yang:ietf-bfd-unsolicited
Prefix: bfd-unsol
Prefix: bfd-unsol Reference: RFC 9468
Reference: RFC YYYY
6. Acknowledgments
Authors would like to thank Acee Lindem, Alvaro Retana, Dan
Romascanu, Derek Atkins, Greg Mirsky, Gyan Mishra, Henning Rogge,
Jeffrey Haas, John Scudder, Lars Eggert, Magnus Westerlund, Mahesh
Jethanandani, Murray Kucherawy, Raj Chetan, Robert Wilton, Roman
Danyliw, Tom Petch, and Zaheduzzaman Sarker for their review and
valuable input.
7. Security Considerations 6. Security Considerations
7.1. BFD Protocol Security Considerations 6.1. BFD Protocol Security Considerations
The same security considerations and protection measures as those The same security considerations and protection measures as those
described in [RFC5880] and [RFC5881] apply to this document. In described in [RFC5880] and [RFC5881] apply to this document. In
addition, with "unsolicited BFD" there is potential risk for addition, with "unsolicited BFD", there is potential risk for
excessive resource usage by BFD from "unexpected" remote systems. To excessive resource usage by BFD from "unexpected" remote systems. To
mitigate such risks, implementations of unsolicited BFD MUST: mitigate such risks, implementations of unsolicited BFD MUST:
* Limit the feature to specific interfaces, and to single-hop BFD * Limit the feature to specific interfaces and to single-hop BFD
sessions using the procedures from [RFC5082]. See Section 5 of sessions using the procedures from [RFC5082]. See Section 5 of
[RFC5881] for the details of these procedures. [RFC5881] for the details of these procedures.
* Apply policy to process BFD packets only from certain subnets or * Apply policy to process BFD packets only from certain subnets or
hosts. hosts.
* Deploy the feature only in an environment that does not offer * Deploy the feature only in an environment that does not offer
anonymous participation. Examples include an IXP, where the IXP anonymous participation. Examples include an IXP, where the IXP
operator will have a business relationship with all IXP operator will have a business relationship with all IXP
participants, or between a provider and its customers. participants, or between a provider and its customers.
7.2. BFD Protocol Authentication Considerations 6.2. BFD Protocol Authentication Considerations
Implementations of unsolicited BFD are RECOMMENDED to use BFD Implementations of unsolicited BFD are RECOMMENDED to use BFD
authentication; see [RFC5880]. If BFD authentication is used, the authentication; see [RFC5880]. If BFD authentication is used, the
strongest BFD authentication mechanism that is supported MUST be strongest BFD authentication mechanism that is supported MUST be
used. used.
In some environments, such as an Internet Exchange Points (IXPs), BFD In some environments, such as IXPs, BFD authentication cannot be used
authentication cannot be used because of the lack of coordination for because of the lack of coordination for the operation of the two
the operation of the two endpoints of the BFD session. endpoints of the BFD session.
In other environments, such as when BFD is used to track the next hop In other environments, such as when BFD is used to track the next hop
of static routes, it is possible to use BFD authentication. This of static routes, it is possible to use BFD authentication. This
comes with the extra cost of configuring matching keychains between comes with the extra cost of configuring matching key chains between
the two endpoints. the two endpoints.
7.3. YANG Module Security Considerations 6.3. YANG Module Security Considerations
The YANG module specified in this document defines a schema for data The YANG module specified in this document defines a schema for data
that is designed to be accessed via network management protocols such that is designed to be accessed via network management protocols such
as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer
is the secure transport layer, and the mandatory-to-implement secure is the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
is HTTPS, and the mandatory-to-implement secure transport is TLS is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446]. [RFC8446].
The NETCONF access control model [RFC8341] provides the means to The Network Configuration Access Control Mode (NACM) [RFC8341]
restrict access for particular NETCONF or RESTCONF users to a provides the means to restrict access for particular NETCONF or
preconfigured subset of all available NETCONF or RESTCONF protocol RESTCONF users to a preconfigured subset of all available NETCONF or
operations and content. RESTCONF protocol operations and content.
There are a number of data nodes defined in this YANG module that are There are a number of data nodes defined in this YANG module that are
writable/creatable/deletable (i.e., config true, which is the writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., edit-config) in some network environments. Write operations (e.g., edit-config)
to these data nodes without proper protection can have a negative to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability: and their sensitivity/vulnerability:
/routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh /routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh
/unsolicited: /unsolicited:
* Data node "enabled" enables creation of unsolicited BFD IP
single-hop sessions globally, i.e., on all interfaces. See
Section 6.1.
* data node "enabled" enables creation of unsolicited BFD IP single- * Data nodes "local-multiplier", "desired-min-tx-interval",
hop sessions globally, i.e. on all interfaces. See Section 7.1. "required-min-rx-interval", and "min-interval" all impact the
* data nodes local-multiplier, desired-min-tx-interval, required- parameters of the unsolicited BFD IP single-hop sessions.
min-rx-interval and min-interval all impact the parameters of the Write operations to these nodes change the rates of BFD packet
unsolicited BFD IP single-hop sessions. Write operations to these generation and detection time of the failures of a BFD session.
nodes change the rates of BFD packet generation and detection time
of the failures of a BFD session.
/routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh /routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh
/interfaces/interface/unsolicited: /interfaces/interface/unsolicited:
* Data node "enabled" enables the creation of unsolicited BFD IP
single-hop sessions on a specific interface. See Section 6.1.
* data node "enabled" enables creation of unsolicited BFD IP single- * Data nodes "local-multiplier", "desired-min-tx-interval",
hop sessions on a specific interface. See Section 7.1. "required-min-rx-interval", and "min-interval" all impact the
* data nodes local-multiplier, desired-min-tx-interval, required- parameters of the unsolicited BFD IP single-hop sessions on the
min-rx-interval and min-interval all impact the parameters of the interface.
unsolicited BFD IP single-hop sessions on the interface.
Some of the readable data nodes in this YANG module may be considered Some of the readable data nodes in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus sensitive or vulnerable in some network environments. It is thus
important to control read access (e.g., via get, get-config, or important to control read access (e.g., via get, get-config, or
notification) to these data nodes. These are the subtrees and data notification) to these data nodes. These are the subtrees and data
nodes and their sensitivity/vulnerability: nodes and their sensitivity/vulnerability:
/routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh /routing/control-plane-protocols/control-plane-protocol/bfd/ip-sh
/sessions/session/role: access to this information discloses the role /sessions/session/role:
of the local system in the creation of the unsolicited BFD session. Access to this information discloses the role of the local system
in the creation of the unsolicited BFD session.
8. References 7. References
8.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004, DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>. <https://www.rfc-editor.org/info/rfc3688>.
skipping to change at page 17, line 11 skipping to change at line 742
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[RFC9314] Jethanandani, M., Ed., Rahman, R., Ed., Zheng, L., Ed., [RFC9314] Jethanandani, M., Ed., Rahman, R., Ed., Zheng, L., Ed.,
Pallagatti, S., and G. Mirsky, "YANG Data Model for Pallagatti, S., and G. Mirsky, "YANG Data Model for
Bidirectional Forwarding Detection (BFD)", RFC 9314, Bidirectional Forwarding Detection (BFD)", RFC 9314,
DOI 10.17487/RFC9314, September 2022, DOI 10.17487/RFC9314, September 2022,
<https://www.rfc-editor.org/info/rfc9314>. <https://www.rfc-editor.org/info/rfc9314>.
8.2. Informative References 7.2. Informative References
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006, DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>. <https://www.rfc-editor.org/info/rfc4271>.
[RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection [RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883, (BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883,
June 2010, <https://www.rfc-editor.org/info/rfc5883>. June 2010, <https://www.rfc-editor.org/info/rfc5883>.
skipping to change at page 17, line 42 skipping to change at line 773
[RFC7947] Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker, [RFC7947] Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,
"Internet Exchange BGP Route Server", RFC 7947, "Internet Exchange BGP Route Server", RFC 7947,
DOI 10.17487/RFC7947, September 2016, DOI 10.17487/RFC7947, September 2016,
<https://www.rfc-editor.org/info/rfc7947>. <https://www.rfc-editor.org/info/rfc7947>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/info/rfc8342>. <https://www.rfc-editor.org/info/rfc8342>.
Acknowledgments
The authors would like to thank Acee Lindem, Alvaro Retana, Dan
Romascanu, Derek Atkins, Greg Mirsky, Gyan Mishra, Henning Rogge,
Jeffrey Haas, John Scudder, Lars Eggert, Magnus Westerlund, Mahesh
Jethanandani, Murray Kucherawy, Raj Chetan, Robert Wilton, Roman
Danyliw, Tom Petch, and Zaheduzzaman Sarker for their reviews and
valuable input.
Authors' Addresses Authors' Addresses
Enke Chen Enke Chen
Palo Alto Networks Palo Alto Networks
3000 Tannery Way
Santa Clara, CA 95054
United States of America
Email: enchen@paloaltonetworks.com Email: enchen@paloaltonetworks.com
Naiming Shen Naiming Shen
Zededa Zededa
160 W Santa Clara Street
San Jose, CA 95113
United States of America
Email: naiming@zededa.com Email: naiming@zededa.com
Robert Raszuk Robert Raszuk
Arrcus Arrcus
2077 Gateway Place 2077 Gateway Place
San Jose, CA 95110 San Jose, CA 95110
United States of America United States of America
Email: robert@raszuk.net Email: robert@raszuk.net
Reshad Rahman Reshad Rahman
Graphiant Equinix
Canada Canada
Email: reshad@yahoo.com Email: reshad@yahoo.com
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