Extended Bidirectional Forwarding Detection
draft-mirmin-bfd-extended-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Greg Mirsky , Xiao Min | ||
| Last updated | 2019-03-05 | ||
| Replaced by | draft-mmm-rtgwg-integrated-oam | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-mirmin-bfd-extended-00
BFD Working Group G. Mirsky
Internet-Draft X. Min
Intended status: Standards Track ZTE Corp.
Expires: September 6, 2019 March 5, 2019
Extended Bidirectional Forwarding Detection
draft-mirmin-bfd-extended-00
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.
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 September 6, 2019.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Mirsky & Min Expires September 6, 2019 [Page 1]
Internet-Draft Extended BFD March 2019
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 2
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. Extended BFD Control Message . . . . . . . . . . . . . . . . 3
3.1. Theory of Operation . . . . . . . . . . . . . . . . . . . 4
3.2. Performance Measurement with Extended BFD Control Message 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Normative References . . . . . . . . . . . . . . . . . . . . 8
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
[RFC5880] 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 became has been broadly deployed. There was a
number of 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.
2. Conventions used in this document
2.1. Terminology
BFD: Bidirectional Forwarding Detection
G-ACh Generic Associated Channel
MTU Maximum Transmission Unit
PMTUD Path MTU Discovery
p2p: Point-to-Point
TLV Type, Length, Value
Mirsky & Min Expires September 6, 2019 [Page 2]
Internet-Draft Extended BFD March 2019
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
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 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 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. A TLV MAY include sub-TLVs
that have the same format as presented in Figure 2.
Mirsky & Min Expires September 6, 2019 [Page 3]
Internet-Draft Extended BFD March 2019
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:
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. Theory of Operation
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 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 is
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Capability ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Capability TLV Format
Mirsky & Min Expires September 6, 2019 [Page 4]
Internet-Draft Extended BFD March 2019
where fields are defined as the following:
o Type - TBA1 allocated by IANA 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 Capability - variable number of octets -
Figure 4 presents defined in this document the capabilities that use
the extended BFD control message:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| L | D |M| Reserved ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Capability Encoding Format
where fields are defined as the following:
o Loss - two bits size field. The least significant of two bits is
set if the node is capable of measuring packet loss using
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- one-bit size field. Set if the node is capable of using the
extended BFD control message in Path MTU Discovery (PMTUD).
[Ed.note: Definition of the PMTUD using the extended BFD control
message is for further version.]
o Reserved - MUST be zeroed on transmission and ignored on receipt.
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
Mirsky & Min Expires September 6, 2019 [Page 5]
Internet-Draft Extended BFD March 2019
supports. The responder MUST set the Final flag in the extended BFD
control message
3.2. 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.
To perform one-way loss and/or delay measurement the BFD node MAY
periodically transmit the extended BFD message with the appropriate
TLV in Asynchronous mode. To perform synthetic loss measurement the
sender MUST monotonically increment the counter of transmitted test
packets. Also, direct-mode loss measurement, as described in
[RFC6374], is supported.
For the one-way measurement the sender MAY use the Performance Metric
TLV (presented in Figure 5) to 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Metric Sub-TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Performance Metric TLV Format
where fields are defined as the following:
o Type - TBA6 allocated by IANA Section 4
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 Metric sub-TLVs - various performance metrics directly measured
and/or calculated at the receiver encoded as TLV. [Ed.note:
Definition of Metric sub-TLVs is for further version.]
To measure the round-trip loss and/or delay metrics the BFD node
transmits the extended BFD control message with the appropriate TLV
with the Poll flag set. Before the transmission of the extended BFD
Mirsky & Min Expires September 6, 2019 [Page 6]
Internet-Draft Extended BFD March 2019
control message, the receiver MUST clear the Poll flag and set the
Final flag.
4. IANA Considerations
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:
+---------------+-------------------------+-------------------------+
| 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 | Extra Padding | This document |
| TBA2 | Capability | This document |
| TBA3 | Loss Measurement | This document |
| TBA4 | Delay Measurement | This document |
| TBA5 | Loss and Delay Measurement | This document |
| TBA6 | Performance Metric | This document |
+-------+----------------------------+---------------+
Table 2: Extended BFD Types
Mirsky & Min Expires September 6, 2019 [Page 7]
Internet-Draft Extended BFD March 2019
5. Security Considerations
This document does not introduce new security aspects but inherits
all security considerations from [RFC5880], [RFC6428], and [RFC6374].
6. 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>.
Appendix A. Acknowledgements
TBD
Authors' Addresses
Greg Mirsky
ZTE Corp.
Email: gregimirsky@gmail.com
Mirsky & Min Expires September 6, 2019 [Page 8]
Internet-Draft Extended BFD March 2019
Xiao Min
ZTE Corp.
Email: xiao.min2@zte.com.cn
Mirsky & Min Expires September 6, 2019 [Page 9]