Internet DRAFT - draft-mirmin-bfd-extended
draft-mirmin-bfd-extended
BFD Working Group G. Mirsky
Internet-Draft X. Min
Intended status: Standards Track ZTE Corp.
Expires: October 16, 2020 April 14, 2020
Extended Bidirectional Forwarding Detection
draft-mirmin-bfd-extended-03
Abstract
This document describes a mechanism to extend the capabilities of
Bidirectional Forwarding Detection (BFD). These extensions enable
BFD to measure performance metrics like packet loss and packet delay.
Also, a method to perform lightweight on-demand authentication is
defined in this specification.
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-
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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 October 16, 2020.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. Extended BFD Control Message . . . . . . . . . . . . . . . . 3
3.1. Extended BFD Capability Negotiation . . . . . . . . . . . 5
3.2. Padding TLV . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Diagnostic TLV . . . . . . . . . . . . . . . . . . . . . 7
3.4. Performance Measurement with Extended BFD Control Message 8
3.5. Lightweight Authentication . . . . . . . . . . . . . . . 9
3.5.1. Lightweight Authentication Mode Negotiation . . . . . 10
3.5.2. Using Lightweight Authentication . . . . . . . . . . 11
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
4.1. Extended BFD Message Types . . . . . . . . . . . . . . . 12
4.2. Lightweight Authentication Modes . . . . . . . . . . . . 13
4.3. Return Codes . . . . . . . . . . . . . . . . . . . . . . 14
5. Security Considerations . . . . . . . . . . . . . . . . . . . 14
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.1. Normative References . . . . . . . . . . . . . . . . . . 15
6.2. Informative References . . . . . . . . . . . . . . . . . 15
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
[RFC5880] has provided the base specification of Bidirectional
Detection (BFD) as the light-weight mechanism to monitor a path
continuity between two systems and detect a failure in the data-
plane. Since its introduction, BFD has been broadly deployed. There
were several attempts to introduce new capabilities in the protocol,
some more successful than others. One of the significant obstacles
to extending BFD capabilities may be seen in the compact format of
the BFD control message. This document introduces an Extended BFD
control message and describes the use of the new format for new BFD
capabilities.
The Extended BFD protocol may be seen as the Operations,
Administration, and Maintenance (OAM) protocol that provides both
Fault Management (FM) Performance Monitoring (PM) OAM functions. In
some networks, for example in a Deterministic Networking (DetNet)
domain [RFC8655], it is easier to ensure that a test packet of a
single OAM protocol is fate-sharing with data packets rather than map
several FM amd PM OAM protocols to that DetNet data flow.
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2. Conventions used in this document
2.1. Terminology
BFD: Bidirectional Forwarding Detection
G-ACh Generic Associated Channel
HMAC Hashed Message Authentication Code
MTU Maximum Transmission Unit
PMTUD Path MTU Discovery
PMTUM Path MTU Monitoring
p2p: Point-to-Point
TLV Type, Length, Value
OAM Operations, Administration, and Maintenance
FM Fault Management
PM Performance Monitoring
DetNet Deterministic Networking
2.2. 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.
3. Extended BFD Control Message
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| BFD Control Message |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Guard Word |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Extended BFD Control Message Format
where fields are defined as the following:
o BFD control message as defined [RFC5880].
o Guard word - four octets long field to identify the role of the
BFD system - sender or responder.
o TLVs - variable-length field that contains commands and/or data
encoded as type-length-value (TLV).
If an Extended BFD control message is encapsulated in IP/UDP, the
value of the Total Length in the IP header includes the length of the
Extended BFD control message while the value of the Length field of
the BFD control message equals the value as defined in [RFC5880]. If
an Extended BFD control message is to be used over Generic Associated
Channel (G-ACh), e.g., [RFC6428] new code point for G-ACh may be
allocated.
Figure 2 displays the generic TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Value ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: General Type-Length-Value Encoding
where fields are defined as the following:
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o Type - two octets long field that defines the encoding of the
Value field
o Length - two octets long field equals length on the Value field in
octets.
o Value - depends on the Type.
TLVs may be included within other TLVs, in which case the former TLVs
are referred to as sub-TLVs. Sub-TLVs have independent types.
3.1. Extended BFD Capability Negotiation
A BFD system also referred to as a node in this document, that
supports Extended BFD first MUST discover whether other nodes in the
given BFD session support the Extended BFD. The node MUST send
Extended BFD control message initiating the Poll Sequence as defined
in [RFC5880]. If the remote system fails to respond with the
Extended BFD control message and the Final flag set, then the
initiator node MUST conclude that the BFD peer does not support the
use of the Extended BFD control messages.
The first Extended BFD control message initiating the Poll Sequence
SHOULD include the Capability TLV that lists capabilities that may be
used at some time during the lifetime of the BFD session. The format
of the Capability TLV and the capabilities that use the Extended BFD
control message are presented in Figure 3.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = Capability | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| L | D | M | Authentication ... | Reserved ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Capability TLV Format
where fields are defined as the following:
o Type - TBA1 allocated by IANA in Section 4
o Length - two octets long field equals length on the Capability
field in octets. The value of the Length field MUST be a multiple
of 4.
o Loss - two bits size field. The least significant of two bits is
set if the node is capable of measuring packet loss using
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periodically transmitted Extended BFD control message. The most
significant of two bits is set if the node is capable of measuring
packet loss using the Poll Sequence with Extended BFD control
message.
o Delay - two bits size field. The least significant of two bits is
set if the node is capable of measuring packet delay using
periodically transmitted Extended BFD control message. The most
significant of two bits is set if the node is capable of measuring
packet delay using the Poll Sequence with Extended BFD control
message.
o MTU - two bits size field. Set if the node is capable of using
the Extended BFD control message in Path MTU Discovery (PMTUD).
or PMTU Monitoring (PMTUM). The least significant of two bits is
set if the node is capable of PMTUD/PMTUM using periodically
transmitted Extended BFD control message. The most significant of
two bits is set if the node is capable of PMTUD/PMTUM using the
Poll Sequence with Extended BFD control message.
o (Lightweight) Authentication - variable-length field. The
Authentication field is used by a BFD system to advertise its
lightweight authentication capabilities. The format and the use
of the Authentication field are defined in Section 3.5.1.
o Reserved - MUST be zeroed on transmission and ignored on receipt.
The Reserved field is zero-padded to align the length of the
Capability TLV to a 4-octet boundary.
The remote BFD node that supports this specification MUST respond to
the Capability TLV with the Extended BFD control message that
includes the Capability TLV listing capabilities the responder
supports. The responder MUST set the Final flag in the Extended BFD
control message.
3.2. Padding TLV
Padding TLV MAY be used to generate Extended BFD control packets of
the desired length.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = Padding | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Padding ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Padding TLV Format
where fields are defined as the following:
o Type - TBA1 allocated by IANA in Section 4
o Length - two octets long field equals length on the Padding field
in octets.
o Padding - variable-length field. MUST be zeroed on transmit and
ignored on receipt.
Padding TLV MAY be used to generate Extended BFD Control packets of
different lengths. That capability is necessary to perform PMTUD,
PMTUM, and measure synthetic packet loss and/or packet delay. When
Padding TLV is used in combination with one of performance
measurement messages carried in Performance Metric TLVs as defined in
Section 3.4, Padding TLV MUST follow the Performance Metric TLV.
Padding TLV MAY be used in PMTUM as part of periodically sent
Extended BFD Control messages. In this case, the number of
consecuitive messages that include Padding TLV MUST be not lesser
than Detect Multiplier to ensure that the remote BFD peer will detect
loss of messages with the Padding TLV. Also, Padding TLV MAY be
present in an Extended BFD Control message with the Poll flag set.
If the remote BFD peer that supports this specification receives an
Extended BFD Control message with Padding TLV, it MUST include the
Padding TLV with the Padding field of the same length as in the
received packet and set the Final flag.
3.3. Diagnostic TLV
Diagnostic TLV MAY be used to characterize the result of the last
requested operation.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = Diagnostic | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Return Code | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Diagnostic TLV Format
where fields are defined as the following:
o Type - TBA6 allocated by IANA in Section 4.
o Length - MUST be set to four.
o Return Code - eight bits-long field. The responding BFD system
can set it to one of the values defined in Section 4.3.
o Reserved - 24 bits-long field. MUST be zeroed on transmit and
ignored on receipt.
3.4. Performance Measurement with Extended BFD Control Message
Loss measurement, delay measurement, and loss/delay measurement
messages can be used in the Extended BFD control message to support
one-way and round-trip measurements. All the messages are
encapsulated as TLVs with Type values allocated by IANA, Section 4.
The sender MAY use the Performance Metric TLV (presented in Figure 6)
to measure performance metrics and obtain the measurement report from
the receiver.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = Performance Metric | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Measurement Message, |
~ Delay Measurement Mesage, or ~
| Combined Loss/Delay Measurement Message |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Performance Metric TLV Format
where fields are defined as the following:
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o Type - TBA3 through TBA5 allocated by IANA in Section 4 as
follows:
* TBA3 - Loss Measurement Type;
* TBA4 - Delay Measurement Type;
* TBA5 - Combined Loss/Delay Measurement Type
o Length - two octets long field equals length on the Metric sub-
TLVs field in octets. The value of the Length field MUST be a
multiple of 4.
o Value - various performance metrics measured either directly or
using synthetic methods accordingly using the messages defined in
Sections 3.1 through 3.3 [RFC6374].
To perform one-way loss and/or delay measurement, the BFD node MAY
periodically transmit the Extended BFD message with one of the TLVs
listed above in Asynchronous mode. To perform synthetic loss
measurement, the sender MUST monotonically increment the counter of
transmitted test packets. When using Performance Metric TLV for
synthetic measurement an Extended BFD Control message MAY also
include Padding TLV. In that case, the Padding TLV MUST immediately
follow Performance Metric TLV. Also, direct-mode loss measurement,
as described in [RFC6374], is supported. Procedures to negotiate and
manipulate transmission intervals defined in Sections 6.8.2 and 6.8.3
in [RFC5880] SHOULD be used to control the performance impact of
using the Extended BFD for performance measurement in the particular
BFD session.
To measure the round-trip loss and/or delay metrics the BFD node
transmits the Extended BFD control message with the Performance
Metric TLV with the Poll flag set. Before the transmission of the
Extended BFD control message with the Performance Metric TLV, the
receiver MUST clear the Poll flag and set the Final flag.
3.5. Lightweight Authentication
Using BFD without any security measures, for example, by exchanging
BFD control packets without authentication, increases the risk of an
attack, especially over multiple nodes. Thus, using BFD without
security measures may cause false positive as well as false negative
defect detection situations. In the former, an attacker may spoof
BFD control packets pretending to be a remote peer and can thus view
the BFD session operation even though the real path had failed. In
the latter, the attacker may spoof altered BFD control message
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indicating that the BFD session is un-operational even though the
path and the remote BFD peer operate normally.
BFD technology[RFC5880] includes optional authentication protection
of BFD control packets to minimize the chances of attacks in a
networking system. However, at least some of the supported
authentication protocols do not provide sufficient protection in
modern networks. Also, current BFD technology requires
authentication of each and every BFD control packet. Such an
authentication requirement can put a computational burden on
networking devices, especially in the Asynchronous mode, at least
because authenticating each BFD control packet can require
substantial computing resources to support packet exchange at high
rates.
This specification defines a lightweight on-demand mode of
authentication for a BFD session. The lightweight authentication is
an optional mode that can be used when the BFD Authentication
[RFC5880] is not in use (bfd.AuthType is zero). The mechanism
includes negotiation (Section 3.5.1) and on-demand authentication
(Section 3.5.2) phases. During the former, BFD peers advertise
supported authentication capabilities and independently select the
commonly supported mode of the authentication. In the authentication
phase, each BFD system transmits, at certain events and periodically,
authenticated BFD control packets in Poll Sequence.
3.5.1. Lightweight Authentication Mode Negotiation
Figure 7 displays the format of the Authentication field that is part
of the Capability Encoding:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Len | AuthL | Authentication Mode ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Lightweight Authentication Capability Field Format
where fields are defined as the following:
o Len (Length) - four-bits long field. The value of the Length
field is equal to the length of the Authentication field,
including the Length, in octets.
o AuthL (Authentication Length) - four bits size field. The value
of the field is, in four octets long words, the longest
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authentication signature the BFD system is capable of supporting
for any of the methods advertised in the AuthMode field.
o Authentication Mode - variable-length field. It is a bit-coded
field that a BFD system uses to list modes of lightweight
authentication it supports.
A BFD system uses Capability TLV, defined in Section 3.1, to discover
the commonly supported mode of the Lightweight Authentication. The
system sets the values in the Authentication field according to
properly reflect its authentication capabilities. The BFD system
transmits the Extended BFD control packet with Capability TLV as the
first in a Poll Sequence. The remote BFD system that supports this
specification receives the Extended BFD control packet with the
advertised Lightweight Authentication modes and stores information
locally. The system responds with the advertisement of its
Lightweight Authentication capabilities in the Extended BFD control
packet with the Final flag set. Each BFD system uses local and
received information about Lightweight Authentication capabilities to
deduce the commonly supported modes and selects from that set the one
that uses the strongest authentication with the longest signature.
If the common set is empty, i.e., none of supported by one BFD system
authentication method is supported by another, an implementation MUST
reflect this in its operational state and SHOULD notify an operator.
3.5.2. Using Lightweight Authentication
After BFD peers select an authentication mode for using in
Lightweight Authentication each BFD system MUST use it to
authenticate each Extended BFD control packet transmitted as part of
a Poll Sequence using Lightweight Authentication TLV presented in
Figure 8.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Type=Lightweight Authentication| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ HMAC ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Lightweight Authentication TLV Format
where fields are defined as the following:
o Type - TBA8 allocated by IANA in Section 4
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o Length - two octets long field equals length on the HMAC (Hashed
Message Authentication Code) field in octets. The value of the
Length field MUST be a multiple of 4.
o HMAC - the hash value calculated on the entire preceding Extended
BFD control packet data.
The Lightweight Authentication TLV MUST be the last TLV in an
Extended BFD control packet. Padding TLV (Section 3.2) MAY be used
to align the length of the Extended BFD control packet, excluding the
Lightweight Authentication TLV, at multiple of 16 boundary.
The BFD system that receives the Extended BFD control packet with the
Lightweight Authentication TLV MUST first validate the
.authentication by calculating the hash over the Extended BFD control
packet. If the validation succeeds, the receiver MUST transmit the
Extended BFD control packet with the Final flag set and the value of
the Return code field in Diagnostic TLV set to None value (Table 5).
If the validation of the lightweight authentication fails, then the
BFD system MUST transmit the Extended BFD control packet with the
Final flag set and the value of the Return Code field of the
Diagnostic TLV set to Lightweight Authentication failed value
(Table 5). The BFD system MUST have a control policy that defines
actions when the system receives the Lightweight Authentication
failed return code.
4. IANA Considerations
4.1. Extended BFD Message Types
IANA is requested to create the Extended BFD Message Types registry.
All code points in the range 1 through 32759 in this registry shall
be allocated according to the "IETF Review" procedure as specified in
[RFC8126]. Code points in the range 32760 through 65279 in this
registry shall be allocated according to the "First Come First
Served" procedure as specified in [RFC8126]. Remaining code points
are allocated according to Table 1:
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+---------------+-------------------------+-------------------------+
| Value | Description | Reference |
+---------------+-------------------------+-------------------------+
| 0 | Reserved | This document |
| 1- 32767 | Mandatory TLV, | IETF Review |
| | unassigned | |
| 32768 - 65279 | Optional TLV, | First Come First Served |
| | unassigned | |
| 65280 - 65519 | Experimental | This document |
| 65520 - 65534 | Private Use | This document |
| 65535 | Reserved | This document |
+---------------+-------------------------+-------------------------+
Table 1: Extended BFD Type Registry
This document defines the following new values in Extended BFD Type
registry:
+-------+---------------------------------+---------------+
| Value | Description | Reference |
+-------+---------------------------------+---------------+
| TBA1 | Padding | This document |
| TBA2 | Capability | This document |
| TBA3 | Loss Measurement | This document |
| TBA4 | Delay Measurement | This document |
| TBA5 | Combined Loss/Delay Measurement | This document |
| TBA6 | Diagnostic | This document |
| TBA8 | Lightweight Authentication | This document |
+-------+---------------------------------+---------------+
Table 2: Extended BFD Types
4.2. Lightweight Authentication Modes
IANA is requested to create a Lightweight Authentication Modes
registry. All code points in this registry shall be allocated
according to the "IETF Review" procedure as specified in [RFC8126].
This document defines the following new values in the Lightweight
Authentication Modes registry:
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+--------------+-------+------------------------+---------------+
| Bit Position | Value | Description | Reference |
+--------------+-------+------------------------+---------------+
| 0 | 0x1 | Keyed SHA-1 | This document |
| 1 | 0x2 | Meticulous Keyed SHA-1 | This document |
| 2 | 0x4 | SHA-256 | This document |
+--------------+-------+------------------------+---------------+
Table 3: Lightweight Authentication Modes
4.3. Return Codes
IANA is requested to create the Extended BFD Return Codes registry.
All code points in the range 1 through 250 in this registry shall be
allocated according to the "IETF Review" procedure as specified in
[RFC8126]. Remaining code points are allocated according to Table 4:
+---------+--------------+---------------+
| Value | Description | Reference |
+---------+--------------+---------------+
| 0 | Reserved | This document |
| 1- 250 | Unassigned | IETF Review |
| 251-253 | Experimental | This document |
| 254 | Private Use | This document |
| 255 | Reserved | This document |
+---------+--------------+---------------+
Table 4: Extended BFD Return Codes Registry
This document defines the following new values in Extended BFD Return
Codes registry:
+-------+-------------------------------------+---------------+
| Value | Description | Reference |
+-------+-------------------------------------+---------------+
| 0 | None | This document |
| 1 | One or more TLVs was not understood | This document |
| 2 | Lightweight Authentication failed | This document |
+-------+-------------------------------------+---------------+
Table 5: Extended BFD Return Codes
5. Security Considerations
This document does not introduce new security aspects but inherits
all security considerations from [RFC5880], [RFC6428], and [RFC6374].
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6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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>.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374,
DOI 10.17487/RFC6374, September 2011,
<https://www.rfc-editor.org/info/rfc6374>.
[RFC6428] Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed.,
"Proactive Connectivity Verification, Continuity Check,
and Remote Defect Indication for the MPLS Transport
Profile", RFC 6428, DOI 10.17487/RFC6428, November 2011,
<https://www.rfc-editor.org/info/rfc6428>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[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>.
6.2. Informative References
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>.
Appendix A. Acknowledgements
TBD
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Authors' Addresses
Greg Mirsky
ZTE Corp.
Email: gregimirsky@gmail.com
Xiao Min
ZTE Corp.
Email: xiao.min2@zte.com.cn
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