BFD Stability
draft-ietf-bfd-stability-15
| Document | Type | Active Internet-Draft (bfd WG) | |
|---|---|---|---|
| Authors | Ashesh Mishra , Mahesh Jethanandani , Ankur Saxena , Santosh Pallagatti , Mach Chen | ||
| Last updated | 2024-07-04 | ||
| Replaces | draft-ashesh-bfd-stability | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Yang Validation | 0 errors, 0 warnings | ||
| Reviews |
YANGDOCTORS Early review
(of
-13)
by Ebben Aries
Ready w/nits
YANGDOCTORS Last Call review
(of
-08)
by Ebben Aries
Ready w/nits
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | In WG Last Call | |
| Document shepherd | Reshad Rahman | ||
| Shepherd write-up | Show Last changed 2020-07-23 | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | Reshad Rahman <reshad@yahoo.com> |
draft-ietf-bfd-stability-15
Network Working Group A. Mishra
Internet-Draft Aalyria Technologies
Intended status: Standards Track M. Jethanandani
Expires: 5 January 2025 Kloud Services
A. Saxena
Ciena Corporation
S. Pallagatti
VMware
M. Chen
Huawei
4 July 2024
BFD Stability
draft-ietf-bfd-stability-15
Abstract
This document describes extensions to the Bidirectional Forwarding
Detection (BFD) protocol to measure BFD stability. Specifically, it
describes a mechanism for detection of BFD packet loss.
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 5 January 2025.
Copyright Notice
Copyright (c) 2024 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
Mishra, et al. Expires 5 January 2025 [Page 1]
Internet-Draft BFD Stability July 2024
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Functionality . . . . . . . . . . . . . . . . . . . . . . . . 3
5. NULL Auth Type . . . . . . . . . . . . . . . . . . . . . . . 3
6. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 5
6.1. Loss Measurement . . . . . . . . . . . . . . . . . . . . 5
6.2. Out of Order Packets . . . . . . . . . . . . . . . . . . 5
7. Stability YANG Module . . . . . . . . . . . . . . . . . . . . 5
7.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 6
7.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8.1. Auth Type . . . . . . . . . . . . . . . . . . . . . . . . 13
8.2. IETF XML Registry . . . . . . . . . . . . . . . . . . . . 13
8.3. The "YANG Module Names" Registry . . . . . . . . . . . . 14
9. Security Consideration . . . . . . . . . . . . . . . . . . . 14
9.1. YANG Security Considerations . . . . . . . . . . . . . . 14
9.2. BFD NULL Auth Security Considerations . . . . . . . . . . 15
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
12. Normative References . . . . . . . . . . . . . . . . . . . . 15
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 17
A.1. Single Hop BFD Configuration . . . . . . . . . . . . . . 17
A.2. Use of NULL Auth . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
The Bidirectional Forwarding Detection (BFD) [RFC5880] protocol
operates by transmitting and receiving BFD control packets, generally
at high frequency, over the datapath being monitored. In order to
prevent significant data loss due to a datapath failure, BFD session
detection time as defined in BFD [RFC5880] is set to the smallest
feasible value.
This document proposes a mechanism to detect lost packets in a BFD
session in addition to the datapath fault detection mechanisms of
BFD. Such a mechanism presents significant value to measure the
stability of BFD sessions and provides data to the operators for the
cause of a BFD failure.
Mishra, et al. Expires 5 January 2025 [Page 2]
Internet-Draft BFD Stability July 2024
This document does not propose any BFD extension to measure data
traffic loss or delay on a link or tunnel and the scope is limited to
BFD packets.
2. Terminology
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 RFC
2119 [RFC2119] and RFC 8174 [RFC8174].
The reader is expected to be familiar with the BFD [RFC5880],
Optimizing BFD Authentication
[I-D.ietf-bfd-optimizing-authentication] and Meticulous Keyed ISAAC
for BFD Authentication [I-D.ietf-bfd-secure-sequence-numbers].
3. Use Cases
Bidirectional Forwarding Detection as defined in BFD [RFC5880] cannot
detect any BFD packet loss if the loss does not last for detection
time. This document proposes a method to detect a dropped packet on
the receiver. For example, if the receiver receives BFD control
packet k at time t but receives packet k+3 at time t+10ms, and never
receives packet k+1 and/or k+2, then it has experienced a drop.
This proposal enables BFD implementations to generate diagnostic
information on the health of each BFD session that could be used to
preempt a failure on a datapath that BFD was monitoring by allowing
time for a corrective action to be taken.
In a faulty datapath scenario, an operator can use BFD health
information to trigger delay and loss measurement OAM protocol
(Connectivity Fault Management (CFM) or Loss Measurement (LM)-Delay
Measurement (DM)) to further isolate the issue.
4. Functionality
The functionality proposed for BFD stability measurement is achieved
by configuring the 'stability' flag in the attached YANG model in
conjunction with any BFD Meticulous Authentication.
5. NULL Auth Type
The NULL Authentication Type, defined here, can be used to provide a
meticulously increasing sequence number for stability measurement.
It provides none of the protections desired for authentication and is
used only to provide BFD stability services to BFD sessions that
otherwise have no authentication in use.
Mishra, et al. Expires 5 January 2025 [Page 3]
Internet-Draft BFD Stability July 2024
If the Authentication Present (A) bit is set in the header, and the
Authentication Type field contains TBD, the Authentication section
has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auth Type | Auth Len | Auth Key ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: NULL Auth Type
where:
Auth Type: The Authentication Type, which in this case is TBD (NULL,
to be assigned by IANA, with a suggested value of 6).
Auth Len: The length of the NULL Auth Type, in bytes; i.e. 8 bytes
Auth Key ID: The authentication key ID in use for this packet. Must
be set to zero and ignored on receipt.
Reserved: This byte MUST be set to zero on transmit and ignored on
receipt.
Sequence Number: The sequence number for this packet. This value is
incremented for each successive packet transmitted for a session.
Implementations will use sequence numbers (bfd.XmitAuthSeq) as
defined in BFD [RFC5880].
If bfd.AuthSeqKnown is 0, bfd.AuthSeqKnown is set to 1, and
bfd.RcvAuthSeq is set to the value of the received Sequence Number
field.
If bfd.AuthSeqKnown is 1, and the received Sequence Number field is
not equal to bfd.RcvAuthSeq + 1 (in a circular number space), then
the loss count is incremented by one and bfd.RcvAuthSeq is set to the
received Sequence Number.
Unlike other authentication mechanisms defined for BFD that provide
an Auth Key/Digest field, when bfd.AuthSeqKnown is 1, the received
Sequence Number MUST NOT be compared vs. bfd.RcvAuthSeq for purposes
of discarding the BFD packets.
Mishra, et al. Expires 5 January 2025 [Page 4]
Internet-Draft BFD Stability July 2024
6. Theory of Operation
This mechanism allows operators to measure the loss of BFD control
packets.
When using MD5 or SHA authentication, BFD MUST use an authentication
type (bfd.AuthType) that is of type meticulous. Other authentication
types that provide for meticulously increasing sequence numbers can
also be used. This includes the NULL authentication mechanism
defined in this document or Meticulous Keyed ISAAC for BFD
Authentication [I-D.ietf-bfd-secure-sequence-numbers].
6.1. Loss Measurement
Loss measurement counts the number of BFD control packets missed at
the receiver during any Detection Time period. The loss is detected
by comparing the Sequence Number field in successive BFD control
packets. The Sequence Number in each successive control packet
generated on a BFD session by the transmitter is incremented by one.
This loss count can then be exposed using the YANG module defined in
the subsequent section.
The first BFD authentication section with a non-zero sequence number,
in a valid BFD control packet, processed by the receiver is used for
bootstrapping the logic.
6.2. Out of Order Packets
Some transmission mechanisms - for example, Link Aggregate Groups
(LAG), or Equal Cost Multipath (ECMP) - can result in out of order
packet delivery. In circumstances where BFD packets are not lost,
but are delivered out of order, strict comparison of increasing
sequence numbers may result in classifying the out of order packets
as packet loss.
Implementations MAY provide mechanisms wherein all expected packets
received across an expected interval but delivered out of order are
not considered lost packets.
7. Stability YANG Module
Mishra, et al. Expires 5 January 2025 [Page 5]
Internet-Draft BFD Stability July 2024
7.1. Data Model Overview
This YANG module augments the "ietf-bfd" module to add a flag
'stability' to enable this feature. The feature statement
'stability' needs to be enabled to indicate that BFD Stability is
supported by the implementation. In addition, a loss count per-
session or lsp for BFD packets that are lost has also been added in
this model.
Mishra, et al. Expires 5 January 2025 [Page 6]
Internet-Draft BFD Stability July 2024
module: ietf-bfd-stability
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:
+--rw stability? boolean {stability}?
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh
/bfd-ip-mh:session-groups/bfd-ip-mh:session-group:
+--rw stability? boolean {stability}?
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/bfd:bfd/bfd-lag:lag
/bfd-lag:sessions/bfd-lag:session:
+--rw stability? boolean {stability}?
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls
/bfd-mpls:session-groups/bfd-mpls:session-group:
+--rw stability? boolean {stability}?
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
/bfd-ip-sh:session-statistics:
+--ro lost-packet-count? yang:counter64 {stability}?
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh
/bfd-ip-mh:session-groups/bfd-ip-mh:session-group
/bfd-ip-mh:sessions/bfd-ip-mh:session-statistics:
+--ro lost-packet-count? yang:counter64 {stability}?
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/bfd:bfd/bfd-lag:lag
/bfd-lag:sessions/bfd-lag:session/bfd-lag:member-links
/bfd-lag:micro-bfd-ipv4/bfd-lag:session-statistics:
+--ro lost-packet-count? yang:counter64 {stability}?
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/bfd:bfd/bfd-lag:lag
/bfd-lag:sessions/bfd-lag:session/bfd-lag:member-links
/bfd-lag:micro-bfd-ipv6/bfd-lag:session-statistics:
+--ro lost-packet-count? yang:counter64 {stability}?
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls
/bfd-mpls:session-groups/bfd-mpls:session-group
/bfd-mpls:sessions/bfd-mpls:session-statistics:
+--ro lost-packet-count? yang:counter64 {stability}?
Mishra, et al. Expires 5 January 2025 [Page 7]
Internet-Draft BFD Stability July 2024
7.2. YANG Module
This YANG module imports Common YANG Types [RFC6991], A YANG Data
Model for Routing [RFC8349], and YANG Data Model for Bidirectional
Forwading Detection (BFD) [RFC9314].
<CODE BEGINS> file "ietf-bfd-stability@2024-07-05.yang"
module ietf-bfd-stability {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-bfd-stability";
prefix "bfds";
import ietf-yang-types {
prefix "yang";
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-routing {
prefix "rt";
reference
"RFC 8349: A YANG Data Model for Routing Management
(NMDA version)";
}
import ietf-bfd {
prefix bfd;
reference
"RFC 9314: YANG Data Model for Bidirectional
Forwarding Detection.";
}
import ietf-bfd-ip-sh {
prefix bfd-ip-sh;
reference
"RFC 9314: YANG Data Model for Bidirectional
Forwarding Detection.";
}
import ietf-bfd-ip-mh {
prefix bfd-ip-mh;
reference
"RFC 9314: YANG Data Model for Bidirectional
Forwarding Detection.";
}
import ietf-bfd-lag {
prefix bfd-lag;
Mishra, et al. Expires 5 January 2025 [Page 8]
Internet-Draft BFD Stability July 2024
reference
"RFC 9314: YANG Data Model for Bidirectional
Forwarding Detection.";
}
import ietf-bfd-mpls {
prefix bfd-mpls;
reference
"RFC 9314: YANG Data Model for Bidirectional
Forwarding Detection.";
}
import ietf-key-chain {
prefix key-chain;
reference
"RFC 8177: YANG Key Chain.";
}
organization
"IETF BFD Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/bfd>
WG List: <rtg-bfd@ietf.org>
Authors: Mahesh Jethanandani (mjethanandani@gmail.com)
Ashesh Mishra (mishra.ashesh@gmail.com)
Ankur Saxena (ankurpsaxena@gmail.com)
Santosh Pallagatti (santosh.pallagati@gmail.com)
Mach Chen (mach.chen@huawei.com).";
description
"This YANG module augments the base BFD YANG model to add
attributes related to BFD Stability. In particular it adds a
a per session count for BFD packets that are lost.
Copyright (c) 2024 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Revised BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
Mishra, et al. Expires 5 January 2025 [Page 9]
Internet-Draft BFD Stability July 2024
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.
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 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.";
revision "2024-07-05" {
description
"Initial Version.";
reference
"RFC XXXX: BFD Stability.";
}
feature stability {
description
"If supported, the feature allows for BFD sessions to be
monitored for frames lost.";
}
identity null-auth {
base key-chain:crypto-algorithm;
description
"BFD Null Auth type defined in this draft.";
reference
"RFC XXXX: BFD Stability.";
}
grouping lost-packet-count {
leaf lost-packet-count {
if-feature "stability";
type yang:counter64;
description
"Number of BFD packets that were lost without bringing the
session down. This counter should be present only if
stability is configured.";
}
description
"Grouping of statistics related to BFD stability.";
}
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" {
leaf stability {
if-feature "stability";
Mishra, et al. Expires 5 January 2025 [Page 10]
Internet-Draft BFD Stability July 2024
type boolean;
must "../bfd-ip-sh:authentication/bfd-ip-sh:meticulous = " +
"'true'";
default false;
description
"If set to true, this enables the BFD session to monitor
for stability; i.e., to watch how many frames are getting
dropped.";
}
description
"Augment the 'bfd' container to add attributes related to BFD
stability for IP Single Hop Sessions.";
}
augment "/rt:routing/rt:control-plane-protocols/" +
"rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh/" +
"bfd-ip-mh:session-groups/bfd-ip-mh:session-group" {
leaf stability {
if-feature "stability";
type boolean;
must "../bfd-ip-mh:authentication/bfd-ip-mh:meticulous = " +
"'true'";
default false;
description
"If set to true, this enables the BFD session to monitor
for stability; i.e., to watch how many frames are getting
dropped.";
}
description
"Augment the 'bfd' container to add attributes related to BFD
stability for Multi Hop Sessions.";
}
augment "/rt:routing/rt:control-plane-protocols/" +
"rt:control-plane-protocol/bfd:bfd/bfd-lag:lag/" +
"bfd-lag:sessions/bfd-lag:session" {
leaf stability {
if-feature "stability";
type boolean;
must "../bfd-lag:authentication/bfd-lag:meticulous = " +
"'true'";
default false;
description
"If set to true, this enables the BFD session to monitor
for stability; i.e., to watch how many frames are getting
dropped.";
}
description
Mishra, et al. Expires 5 January 2025 [Page 11]
Internet-Draft BFD Stability July 2024
"Augment the 'bfd' container to add attributes related to BFD
stability for LAG session.";
}
augment "/rt:routing/rt:control-plane-protocols/" +
"rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls/" +
"bfd-mpls:session-groups/bfd-mpls:session-group" {
leaf stability {
if-feature "stability";
type boolean;
must "../bfd-mpls:authentication/bfd-mpls:meticulous = " +
"'true'";
default false;
description
"If set to true, this enables the BFD session to monitor
for stability; i.e., to watch how many frames are getting
dropped.";
}
description
"Augment the 'bfd' container to add attributes related to BFD
stability for MPLS.";
}
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/" +
"bfd-ip-sh:session-statistics" {
uses lost-packet-count;
description
"Augment the 'bfd' container to add statistics related to BFD
stability for IP Single Hop Sessions.";
}
augment "/rt:routing/rt:control-plane-protocols/" +
"rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh/" +
"bfd-ip-mh:session-groups/bfd-ip-mh:session-group/" +
"bfd-ip-mh:sessions/bfd-ip-mh:session-statistics" {
uses lost-packet-count;
description
"Augment the 'bfd' container to add statistics related to BFD
stability for IP Multi Hop Sessions.";
}
augment "/rt:routing/rt:control-plane-protocols/" +
"rt:control-plane-protocol/bfd:bfd/bfd-lag:lag/" +
"bfd-lag:sessions/bfd-lag:session/bfd-lag:member-links/" +
"bfd-lag:micro-bfd-ipv4/bfd-lag:session-statistics" {
uses lost-packet-count;
Mishra, et al. Expires 5 January 2025 [Page 12]
Internet-Draft BFD Stability July 2024
description
"Augment the 'bfd' container to add statistics related to BFD
stability for Micro BFD sessions for IPv4.";
}
augment "/rt:routing/rt:control-plane-protocols/" +
"rt:control-plane-protocol/bfd:bfd/bfd-lag:lag/" +
"bfd-lag:sessions/bfd-lag:session/bfd-lag:member-links/" +
"bfd-lag:micro-bfd-ipv6/bfd-lag:session-statistics" {
uses lost-packet-count;
description
"Augment the 'bfd' container to add statistics related to BFD
stability for Micro BFD sessions for IPv6.";
}
augment "/rt:routing/rt:control-plane-protocols/" +
"rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls/" +
"bfd-mpls:session-groups/bfd-mpls:session-group/" +
"bfd-mpls:sessions/bfd-mpls:session-statistics" {
uses lost-packet-count;
description
"Augment the 'bfd' container to add statistics related to BFD
stability for MPLS sessions.";
}
}
<CODE ENDS>
8. IANA Considerations
This document requests one new authentication type and registers one
URIs in the "ns" subregistry of the "IETF XML" registry [RFC3688].
8.1. Auth Type
This document requests an update to the registry titled "BFD
Authentication Types". IANA is requested to assign a new BFD
AuthType:
* NULL Auth Type, with a suggested value of 6.
8.2. IETF XML Registry
Following the format in [RFC3688], the following registrations are
requested:
Mishra, et al. Expires 5 January 2025 [Page 13]
Internet-Draft BFD Stability July 2024
URI: urn:ietf:params:xml:ns:yang:ietf-bfd-stability
Registrant Contact: The IESG
XML: N/A, the requested URI is an XML namespace.
8.3. The "YANG Module Names" Registry
This document registers one YANG modules in the "YANG Module Names"
registry [RFC6020]. Following the format in [RFC6020], the following
registrations are requested:
name: ietf-bfd-stability
namespace: urn:ietf:params:xml:ns:yang:ietf-bfd-stability
prefix: bfds
reference: RFC XXXX
9. Security Consideration
9.1. YANG 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
[RFC8446]. The NETCONF Access Control Model (NACM) [RFC8341]
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.
The YANG module does not define any writeable/creatable/deletable
data nodes that can have an adverse impact on a BFD session.
The only readable data nodes in 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.
The model defines a read-only node to indicate the number of packets
that were lost. Access to this information may allow a malicious
user information on which links are experiencing issues. In
addition, and as stated in Out of Order Packets (Section 6.2), on
links such as LAG or ECMP, there is a possibility of packets being
delivered out of order. A strict comparison of increasing sequence
numbers may result in classifying those out of order packets as
packet loss.
Mishra, et al. Expires 5 January 2025 [Page 14]
Internet-Draft BFD Stability July 2024
The YANG module does not define any RPC operations.
9.2. BFD NULL Auth Security Considerations
Use of a BFD authentication mechanism that protects the BFD packets
is RECOMMENDED.
The Security Considerations of [RFC5880] for unauthenticated BFD all
apply to the new NULL authentication type. The NULL Authentication
type, defined in this document, provides none of the properties
desired for authenticating BFD packets. It is intended to provide
BFD sessions that otherwise would not use authentication a sequence
number that can be used for purposes of detecting lost packets.
The lack of a computed AuthKey/Digest over the BFD packet but the
presence of a Sequence Number makes this authentication type
susceptible to injection attacks. BFD without authentication is
vulnerable to session resets; the NULL Auth type does not change
this.
When the NULL Authentication type is used for BFD Stability purposes,
maliciously injected packets that do not reset the BFD session can
resemble high packet loss. Sessions such as, multi-hop routed paths,
tunnels without authentication, or MPLS LSP, therefore, have security
guarantees that are identical to situations where BFD is run without
authentication.
10. Contributors
The authors of this document would like to acknowledge Jeff Haas as a
contributor to this document. Jeff played a role not only as a
shepherd but also actively contributed to the improvement of the
document. In addition, Manav Bhatia and Peng Fang contributed to
this document.
11. Acknowledgements
Authors would like to thank Nobo Akiya, Dileep Singh, Basil Saji,
Sagar Soni, Albert Fu and Mallik Mudigonda who also contributed to
this document.
12. Normative References
Mishra, et al. Expires 5 January 2025 [Page 15]
Internet-Draft BFD Stability July 2024
[I-D.ietf-bfd-optimizing-authentication]
Jethanandani, M., Mishra, A., Saxena, A., Bhatia, M., and
J. Haas, "Optimizing BFD Authentication", Work in
Progress, Internet-Draft, draft-ietf-bfd-optimizing-
authentication-17, 1 July 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-bfd-
optimizing-authentication-17>.
[I-D.ietf-bfd-secure-sequence-numbers]
DeKok, A., Jethanandani, M., Agarwal, S., Mishra, A., and
A. Saxena, "Meticulous Keyed ISAAC for BFD
Authentication", Work in Progress, Internet-Draft, draft-
ietf-bfd-secure-sequence-numbers-15, 20 May 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-bfd-
secure-sequence-numbers-15>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[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,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
Mishra, et al. Expires 5 January 2025 [Page 16]
Internet-Draft BFD Stability July 2024
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[RFC8349] Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
Routing Management (NMDA Version)", RFC 8349,
DOI 10.17487/RFC8349, March 2018,
<https://www.rfc-editor.org/info/rfc8349>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC9314] Jethanandani, M., Ed., Rahman, R., Ed., Zheng, L., Ed.,
Pallagatti, S., and G. Mirsky, "YANG Data Model for
Bidirectional Forwarding Detection (BFD)", RFC 9314,
DOI 10.17487/RFC9314, September 2022,
<https://www.rfc-editor.org/info/rfc9314>.
Appendix A. Examples
This section tries to show some examples in how the model can be
configured for stability.
A.1. Single Hop BFD Configuration
This example demonstrates how a Single Hop BFD session can be
configured to enable monitoring of a session for stability.
=============== NOTE: '\' line wrapping per RFC 8792 ===============
<?xml version="1.0" encoding="UTF-8"?>
<key-chains
xmlns="urn:ietf:params:xml:ns:yang:ietf-key-chain"
xmlns:kc="urn:ietf:params:xml:ns:yang:ietf-key-chain">
<key-chain>
<name>bfd-stability-config</name>
<description>"An example for BFD Stabalized configuration."</de\
scription>
Mishra, et al. Expires 5 January 2025 [Page 17]
Internet-Draft BFD Stability July 2024
<key>
<key-id>55</key-id>
<lifetime>
<send-lifetime>
<start-date-time>2017-01-01T00:00:00Z</start-date-time>
<end-date-time>2017-02-01T00:00:00Z</end-date-time>
</send-lifetime>
<accept-lifetime>
<start-date-time>2016-12-31T23:59:55Z</start-date-time>
<end-date-time>2017-02-01T00:00:05Z</end-date-time>
</accept-lifetime>
</lifetime>
<crypto-algorithm>kc:sha-1</crypto-algorithm>
</key>
</key-chain>
</key-chains>
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:if-type="urn:ietf:params:xml:ns:yang:iana-if-type">
<interface>
<name>eth0</name>
<type>if-type:ethernetCsmacd</type>
</interface>
</interfaces>
<routing
xmlns="urn:ietf:params:xml:ns:yang:ietf-routing"
xmlns:bfd-types="urn:ietf:params:xml:ns:yang:ietf-bfd-types"
xmlns:stability="urn:ietf:params:xml:ns:yang:ietf-bfd-stability\
">
<control-plane-protocols>
<control-plane-protocol>
<type>bfd-types:bfdv1</type>
<name>name:BFD</name>
<bfd xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd">
<ip-sh xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd-ip-sh">
<sessions>
<session>
<interface>eth0</interface>
<dest-addr>2001:db8:0:113::101</dest-addr>
<desired-min-tx-interval>10000</desired-min-tx-interv\
al>
<required-min-rx-interval>
10000
</required-min-rx-interval>
<stability:stability>true</stability:stability>
<authentication>
<key-chain>bfd-stability-config</key-chain>
<meticulous>true</meticulous>
Mishra, et al. Expires 5 January 2025 [Page 18]
Internet-Draft BFD Stability July 2024
</authentication>
</session>
</sessions>
</ip-sh>
</bfd>
</control-plane-protocol>
</control-plane-protocols>
</routing>
A.2. Use of NULL Auth
This example demonstrates how to configure NULL Auth to enable
monitoring of a session for stability.
=============== NOTE: '\' line wrapping per RFC 8792 ===============
<?xml version="1.0" encoding="UTF-8"?>
<key-chains
xmlns="urn:ietf:params:xml:ns:yang:ietf-key-chain"
xmlns:stability="urn:ietf:params:xml:ns:yang:ietf-bfd-stability\
">
<key-chain>
<name>bfd-stability-config</name>
<description>"An example for BFD Stability configuration."</des\
cription>
<key>
<key-id>55</key-id>
<lifetime>
<send-lifetime>
<start-date-time>2017-01-01T00:00:00Z</start-date-time>
<end-date-time>2017-02-01T00:00:00Z</end-date-time>
</send-lifetime>
<accept-lifetime>
<start-date-time>2016-12-31T23:59:55Z</start-date-time>
<end-date-time>2017-02-01T00:00:05Z</end-date-time>
</accept-lifetime>
</lifetime>
<crypto-algorithm>stability:null-auth</crypto-algorithm>
</key>
</key-chain>
</key-chains>
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:if-type="urn:ietf:params:xml:ns:yang:iana-if-type">
<interface>
<name>eth0</name>
<type>if-type:ethernetCsmacd</type>
Mishra, et al. Expires 5 January 2025 [Page 19]
Internet-Draft BFD Stability July 2024
</interface>
</interfaces>
<routing
xmlns="urn:ietf:params:xml:ns:yang:ietf-routing"
xmlns:bfd-types="urn:ietf:params:xml:ns:yang:ietf-bfd-types"
xmlns:stability="urn:ietf:params:xml:ns:yang:ietf-bfd-stability\
">
<control-plane-protocols>
<control-plane-protocol>
<type>bfd-types:bfdv1</type>
<name>name:BFD</name>
<bfd xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd">
<ip-sh xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd-ip-sh">
<sessions>
<session>
<interface>eth0</interface>
<dest-addr>2001:db8:0:113::101</dest-addr>
<desired-min-tx-interval>10000</desired-min-tx-interv\
al>
<required-min-rx-interval>
10000
</required-min-rx-interval>
<stability:stability>true</stability:stability>
<authentication>
<key-chain>bfd-stability-config</key-chain>
<meticulous>true</meticulous>
</authentication>
</session>
</sessions>
</ip-sh>
</bfd>
</control-plane-protocol>
</control-plane-protocols>
</routing>
Authors' Addresses
Ashesh Mishra
Aalyria Technologies
Email: ashesh@aalyria.com
Mahesh Jethanandani
Kloud Services
CA
United States of America
Email: mjethanandani@gmail.com
Mishra, et al. Expires 5 January 2025 [Page 20]
Internet-Draft BFD Stability July 2024
Ankur Saxena
Ciena Corporation
3939 North 1st Street
San Jose, CA 95134
United States of America
Email: ankurpsaxena@gmail.com
URI: www.ciena.com
Santosh Pallagatti
VMware
Bangalore 560103
Karnataka
India
Email: santosh.pallagatti@gmail.com
Mach Chen
Huawei
Email: mach.chen@huawei.com
Mishra, et al. Expires 5 January 2025 [Page 21]