BIER Ping and Trace
draft-ietf-bier-ping-10
| Document | Type | Active Internet-Draft (bier WG) | |
|---|---|---|---|
| Authors | Nagendra Kumar Nainar , Carlos Pignataro , Nobo Akiya , Lianshu Zheng , Mach Chen , Greg Mirsky | ||
| Last updated | 2023-05-19 | ||
| Replaces | draft-kumarzheng-bier-ping | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Reviews |
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INTDIR Early review
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||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Consensus: Waiting for Write-Up | |
| Document shepherd | Mankamana Prasad Mishra | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | mankamana mishra <mankamis@cisco.com> |
draft-ietf-bier-ping-10
Network Work group N. Kumar
Internet-Draft C. Pignataro
Intended status: Standards Track Cisco Systems, Inc.
Expires: 20 November 2023 N. Akiya
Big Switch Networks
L. Zheng
Individual Contributor
M. Chen
Huawei Technologies
G. Mirsky
Ericsson
19 May 2023
BIER Ping and Trace
draft-ietf-bier-ping-10
Abstract
Bit Index Explicit Replication (BIER) is an architecture that
provides optimal multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain any multicast-related per-
flow state. BIER also does not require any explicit tree-building
protocol for its operation. A multicast data packet enters a BIER
domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs).
The BFIR router adds a BIER header to the packet. The BIER header
contains a bit-string in which each bit represents exactly one BFER
to forward the packet to. The set of BFERs to which the multicast
packet needs to be forwarded is expressed by setting the bits that
correspond to those routers in the BIER header.
This document describes the mechanism and basic BIER OAM packet
format that can be used to perform failure detection and isolation on
the BIER data plane.
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/.
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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 20 November 2023.
Copyright Notice
Copyright (c) 2023 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 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 . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. BIER OAM . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. BIER OAM message format . . . . . . . . . . . . . . . . . 4
3.2. Return Code . . . . . . . . . . . . . . . . . . . . . . . 7
3.3. BIER OAM TLV . . . . . . . . . . . . . . . . . . . . . . 9
3.3.1. Original SI-BitString TLV . . . . . . . . . . . . . . 9
3.3.2. Target SI-BitString TLV . . . . . . . . . . . . . . . 10
3.3.3. Incoming SI-BitString TLV . . . . . . . . . . . . . . 11
3.3.4. Downstream Mapping TLV . . . . . . . . . . . . . . . 12
3.3.5. Responder BFER TLV . . . . . . . . . . . . . . . . . 15
3.3.6. Responder BFR TLV . . . . . . . . . . . . . . . . . . 15
3.3.7. Upstream Interface TLV . . . . . . . . . . . . . . . 16
3.4. Multipath Entropy Data Encoding . . . . . . . . . . . . . 17
4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1. BIER OAM Processing . . . . . . . . . . . . . . . . . . . 17
4.2. Per BFER ECMP Discovery . . . . . . . . . . . . . . . . . 17
4.3. Sending BIER Echo Request . . . . . . . . . . . . . . . . 18
4.4. Receiving BIER Echo Request . . . . . . . . . . . . . . . 19
4.5. Sending Echo Reply . . . . . . . . . . . . . . . . . . . 21
4.6. Receiving Echo Reply . . . . . . . . . . . . . . . . . . 22
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
5.1. UDP Port Number . . . . . . . . . . . . . . . . . . . . . 22
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5.2. BIER OAM Parameters . . . . . . . . . . . . . . . . . . . 22
5.3. BIER OAM Message Type . . . . . . . . . . . . . . . . . . 22
5.4. BIER Echo Request/Echo Reply Parameters . . . . . . . . . 23
5.4.1. BIER Echo Request/Echo Reply Message Types . . . . . 23
5.4.2. BIER Echo Reply Modes . . . . . . . . . . . . . . . . 24
5.4.3. BIER Echo Return Codes . . . . . . . . . . . . . . . 25
5.5. TLVs . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6. Security Considerations . . . . . . . . . . . . . . . . . . . 27
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 28
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.1. Normative References . . . . . . . . . . . . . . . . . . 28
8.2. Informative References . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29
1. Introduction
[RFC8279] introduces and explains BIER architecture that provides
optimal multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain any multicast-related per-
flow state. BIER also does not require any explicit tree-building
protocol for its operation. A multicast data packet enters a BIER
domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs).
The BFIR router adds a BIER header to the packet. The BIER header
contains a bit-string in which each bit represents exactly one BFER
to forward the packet to. The set of BFERs to which the multicast
packet needs to be forwarded is expressed by setting the bits that
correspond to those routers in the BIER header.
Operations, Administration, and Maintenance (OAM) mechanisms are
expected to support the detection of network failures. After the
detection, operators localize and characterize the network defect. A
query-based tool, e.g., ICMP [RFC0792] and LSP Ping [RFC8029],
[RFC6425], is broadly used to detect and localize a network defect.
Additionally, this mechanism can be used to check the consistency
between the data and control planes. This document describes the
mechanism and basic BIER OAM packet format that can be used to
perform failure detection and isolation on the BIER data plane
without any dependency on other layers, like the IP layer.
2. Conventions used in this document
2.1. Terminology
BFER - Bit-Forwarding Egress Router
BFIR - Bit-Forwarding Ingress Router
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BFR - Bit-Forwarding Router
BIER - Bit Index Explicit Replication
DDMAP - Downstream Detailed Mapping TLV
ECMP - Equal Cost Multi-Path
OAM - Operation, Administration, and Maintenance
SI - Set Identifier
QTF - Querier Timestamp Format
RTF - Responder Timestamp Format
NTP - Network Time Protocol
MTU - Maximum Transmission Unit
DA - Downstream Address
DIA - Downstream Interface Address
DoS - Denial-of-Service
PTP - Precision Time Protocol
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. BIER OAM
BIER OAM is defined to stay within the BIER layer by directly
following the BIER header without mandating the need for an IP
header. [RFC8296] defines a 4-bit field as "Proto" to identify the
payload following the BIER header. When the payload is BIER OAM, the
"Proto" field will be set to 5 as defined in [RFC8296]
3.1. BIER OAM message format
The BIER OAM packet header format that follows the BIER header is
displayed in Figure 1.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver | Message Type | Proto | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OAM Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Message Type Dependent Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: BIER OAM Header
Ver - a four-bit field that indicates the current version of the
BIER OAM header. The current value is 1. The version number is
to be incremented whenever a change is made that affects the
ability of an implementation to parse or process the BIER OAM
header correctly. For example, if syntactic or semantic changes
are made to any of the fixed fields.
Message Type - a six-bit field that identifies OAM protocol.
Values defined in this document are as follows:
Value Description
-------- ---------------
1 Echo Request
2 Echo Reply
Proto - a six-bit field. This field is used to define if there is
any data packet immediately following the OAM payload, which may
be used by a hybrid OAM [RFC7799]. This field MUST be set to 0 if
there is no data packet following the OAM payload. Value is one
from the IANA registry "BIER Next Protocol Identifiers" [RFC8296].
Reserved - a fourteen-bit field. The value MUST be zeroed on
transmission and ignored on receipt.
OAM Message Length - a two-octet field that reflects the length of
the OAM message, including the header and the Messsage Type
Dependent Data.
Message Type Dependant Data - a variable-length field that
includes the OAM message identified by the value of the Message
Type filed.
The Echo Request/Reply header format displayed in Figure 2
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver | Echo Req/Rep | Proto | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Echo Request/Reply Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QTF | RTF | Reply Mode | Return Code | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender's Handle |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp Sent |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp Received |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: BIER Echo Request/Reply Format
Proto field MUST be set to 0 for Echo Request/Reply header.
QTF (Querier Timestamp Format) - a four-bit field. When the field
is set to 2, the Timestamp Sent field is (in seconds and
microseconds, according to the Initiator's clock) in NTP format
[RFC5905]. When the value of the QTF field is 3, the Timestamp
Sent's format is the IEEE 1588-2008 (1588v2) Precision Time
Protocol (PTP) [IEEE.1588.2008] format. Any other value MAY be
considered as a sanity check failure.
RTF (Responder Timestamp Format) - a four-bit field. When the
field is set to 2, the Timestamp Received field is (in seconds and
microseconds, according to the Initiator's clock) in NTP format
[RFC5905]. When filed's value is 3, the format of the Timestamp
Received is as defined in IEEE 1588-2008 (1588v2) Precision Time
Protocol [IEEE.1588.2008]. Any other value MAY be considered as a
sanity check failure.
The sender of the BIER Echo Request might receive the BIER Echo Reply
with RTF different from the Sender's QTF, Thus, the Sender MUST be
able to interpret both timestamp formats, i.e., NTP [RFC5905] and PTP
[IEEE.1588.2008].
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The Reply Mode - a one-octet field. The value MUST be set to one
of the following values:
Value Description
-------- ---------------
1 Do not Reply
2 Reply via IPv4/IPv6 UDP packet
3 Reply via BIER packet
When Reply Mode is set to 1, the receiver will not send any reply.
This mode can be used for unidirectional path validation. When
the Reply Mode is set to 2, the Responder Bit-Forwarding Router
(BFR) encapsulates the Echo reply payload with the IP/UDP header.
When the Initiator intends to validate the return BIER path, the
Reply Mode will be set to 3 so that the Responder BFR will
encapsulate the Echo Reply with the BIER header.
Return Code - a one-octet field. The value MUST be set to zero if
the Type is "BIER Echo Request". The value of the Return Code
filed MUST be set to one of the values defined in Section 3.2, if
the Type is "BIER Echo Reply".
Reserved - a one-octet field. The Reserved field MUST be zeroed
on transmit and MUST be ignored on receipt.
Sender's Handle - a four-octet field. The Sender's Handle is
filled by the Initiator, and returned unchanged by responder BFR.
This value can be used for matching the replies to the request.
Sequence Number - a four-octet field. The value of the field is
assigned by the Initiator and can be used to detect any missed
replies.
Timestamp - each field (Sent and Received) is an eight-octet
field. The Timestamp Sent is the time when the Echo Request is
sent. The Timestamp Received in Echo Reply is the time
(accordingly to responding BFR clock) that the corresponding Echo
Request was received. The format depends on the QTF/RTF value.
TLVs - Carries the TLVs as defined in Section 3.3.
3.2. Return Code
The responder uses the Return Code field to reply with a validity
check or other error message to Initiator. It does not carry any
meaning in Echo Request and MUST be set to zero. The Return Code can
be one of the following:
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Value Value Meaning
------ ---------------
0 No return code
1 Malformed Echo Request received
2 One or more of the TLVs is not supported
3 Replying BFR is the only BFER in header BitString
4 Replying BFR is one of the BFERs in header BitString
5 Packet-Forward-Success
6 Invalid Multipath Info Request
8 No matching entry in the forwarding table
9 Set-Identifier Mismatch
10 DDMAP Mismatch
"No return code" will be used by Initiator in the Echo Request. This
value MUST NOT be used in Echo Reply.
"Malformed Echo Request received" will be used by any BFR if the
received Echo Request packet is not properly formatted.
When a receiver does not support any TLV included in the Echo
Request, the Return code will be set to "One or more of the TLVs is
not supported" carrying the respective TLVs.
When the received header BitString in the Echo Request packet
contains only its Bit-ID, "Replying BFR is the only BFER in header
BitString" is set in the reply. This value implies that the receiver
is BFER, and the packet is not forwarded to any more neighbors.
When the received header BitString in the Echo Request packet
contains its Bit-ID in addition to other Bit-IDs, "Replying BFR is
one of the BFERs in header BitString" is set in the reply. This
value implies that the responder is a BFER and the packet is further
forwarded to one or more neighbors.
Any transit BFR will send the Echo Reply with "Packet-Forward-
Success", if the TLV in the received Echo Request is understood and
the forwarding table has forwarding entries for the BitString. This
behavior is demonstrated by a transit BFR during traceroute mode.
When the Echo Request is received with multipath info for more than
one BFER, the Return Code is set to "Invalid Multipath Info Request".
If the BitString cannot be matched in the local forwarding table, the
BFR will use "No matching entry in the forwarding table" in the
reply.
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If the BIER-MPLS label in the received Echo Request is not the one
assigned for SI in Original SI-BitString TLV, "Set-Identifier
Mismatch" is set in order to report the mismatch.
If the BitString in Header-H does not match the BitString in Egress
BitString Sub-TLV of DDMAP TLV, a responding BFR will use "DDMAP
Mismatch" to report the problem.
3.3. BIER OAM TLV
This section defines various TLVs that can be used in BIER OAM
packet. The TLVs (Type-Length-Value tuples) have 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Value ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Type-Length-Value Format Used in BIER Echo Request/Reply
TLV Types are defined below; Length is the length of the Value field
in octets. The Value field depends on the TLV Type.
3.3.1. Original SI-BitString TLV
The Original SI-BitString TLV carries the set of BFERs and carries
the same BitString that the Initiator includes in the BIER header.
This TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 1 | Length = variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID | Sub-domain ID |BS Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (first 32 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 4: The Format of the Original SI-BitString TLV
Set ID - a one-octet field that is set to the value of the Set
Identifier to which the BitString belongs. This value is derived as
defined in [RFC8279].
Sub-domain ID - a one-octet field that is set to the Sub-domain value
to which BFER in BitString belongs.
BS Len - a four-bit field that is set based on the length of
BitString as defined in [RFC8296] reflected in four-octet words.
Reserved - a twelve-bit field. Its value MUST be zeroed on
transmission and ignored on receipt.
BitString - a variable length field. The BitString field carries the
set of BFR-IDs that Initiator will include in the BIER header. This
TLV MUST be included by the Initiator in the Echo Request packet.
Any Initiator MUST include this TLV in the Echo Request packet.
3.3.2. Target SI-BitString TLV
The Target SI-BitString TLV carries the set of BFERs from which the
Initiator expects the reply. This TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 2 | Length = variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID | Sub-domain ID |BS Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (first 32 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: The Format of the Target SI-BitString TLV
Set ID field is set to the Set Identifier to which the BitString
belongs.This value is derived as defined in [RFC8279].
Sub-domain ID is set to the Sub-domain value to which BFER in
BitString belongs.
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BS Len is set based on the length of BitString as defined in
[RFC8296]
Reserved - the value MUST be zeroed on transmission and ignored on
receipt.
The BitString field carries the set of BFR-IDs of BFER(s) that
Initiator expects a response. The BitString in this TLV may be
different from the BitString in the BIER header and allows control of
the BFER responding to the Echo Request. This TLV MUST be included
by Initiator in the BIER OAM packet if the Downstream Mapping TLV
(Section 3.3.4) is included.
3.3.3. Incoming SI-BitString TLV
The Incoming SI-BitString TLV will be included by Responder BFR in
Reply message and copies the BitString from the BIER header of
incoming Echo Request message. This TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 3 | Length = variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID | Sub-domain ID |BS Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (first 32 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: The Format of the Incoming SI-BitString TLV
Set ID field is set to the Set Identifier to which the BitString
belongs. This value is derived as defined in [RFC8279]
Sub-domain ID is set to the Sub-domain value to which BFER in
BitString belongs.
BS Len is set based on the length of BitString as defined in
[RFC8296].
Reserved - the value MUST be zeroed on transmission and ignored on
receipt.
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The BitString field copies the BitString from the BIER header of the
incoming Echo Request. A Responder BFR SHOULD include this TLV in
Echo Reply if the Echo Request is received with the I flag set in
Downstream Mapping TLV.
An Initiator MUST NOT include this TLV in Echo Request.
3.3.4. Downstream Mapping TLV
This TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 4 | Length = variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MTU | Address Type | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Address (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Interface Address (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. .
. List of Sub-TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: The Format of the Downstream Mapping TLV
MTU A two-octet field. The value is the Maximum Transmission Unit
(MTU) value of the egress interface.
Address Type A one-octet field. The Address Type indicates the
address type and length of the IP address for the downstream
interface. The Address type is set to one of the following
values:
Type Addr. Type DA Length DIA Length
------- --------------- ---------- ----------
1 IPv4 Numbered 4 4
2 IPv4 Unnumbered 4 4
3 IPv6 Numbered 16 16
4 IPv6 Unnumbered 16 4
DA Length
Downstream Address (DA) field Length
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DIA Length
Downstream Interface Address (DIA) field Length
Flags
The Flags field has the following format:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| Reserved |I|
+-+-+-+-+-+-+-+-+
Figure 8: The Flags Field Format
Reserved - a seven-bit field. Its value MUST be zeroed on
transmission and ignored on receipt.
I - a one-bit field. When I flag is set, the Responding BFR MUST
include the Incoming SI- BitString TLV in Echo Reply message.
Downstream Address and Downstream Interface Address
each field is either four-octet or sixteen-octet, depending on the
value of Address Type field.
If the Address Type is 1, the Downstream Address MUST be set to
IPV4 BFR-Prefix of downstream BFR and Downstream Interface Address
is set to the downstream interface address.
If the Address Type is 2, the Downstream Address MUST be set to
IPV4 BFR-Prefix of downstream BFR and Downstream Interface Address
is set to the index assigned by upstream BFR to the interface.
If the Address Type is 3, the Downstream Address MUST be set to
IPV6 BFR-Prefix of downstream BFR and Downstream Interface Address
is set to the downstream interface address.
If the Address Type is 4, the Downstream Address MUST be set to
IPv6 BFR-Prefix of downstream BFR and Downstream Interface Address
is set to the index assigned by upstream BFR to the interface.
3.3.4.1. Downstream Detailed Mapping Sub-TLVs
This section defines the optional Sub-TLVs that can be included in
Downstream Mapping TLV.
Sub-TLV Type Value
------------ -------------
1 Multipath Entropy Data
2 Egress BitString
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3.3.4.1.1. Multipath Entropy Data
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 = 1 | Length = variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M| Reserved | |
+-+-+-+-+-+-+-+-+-+ |
| |
| (Multipath Information) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: The Format of the Multipath Data Blob
M Flag This flag is set to 0 if all packets will be forwarded out
through the interface defined in the Downstream Mapping TLV. When
set to 1, Multipath Information will be defined by the Bit masked
Entropy data.
Reserved The value MUST be zeroed on transmission and ignored on
receipt.
Multipath Information Entropy Data is encoded as defined in
Section 3.4.
3.3.4.1.2. Egress BitString Sub-TLV
Responder BFR MAY include this Sub-TLV with the rewritten BitString
in the outgoing interface as defined in Section 6.1 of [RFC8279].
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 = 2 | Length = variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID | Sub-domain ID |BS Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (first 32 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: The Egress BitString Sub-TLV Format
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Set ID field is set to the Set Identifier to which the BitString
belongs. This value is derived as defined in [RFC8279].
Sub-domain ID is set to the Sub-domain value to which BFER in
BitString belongs.
BS Len is set based on the length of BitString as defined in
[RFC8296].
Reserved - the value MUST be zeroed on transmission and ignored on
receipt.
The BitString field copies the rewritten BitString in the outgoing
interface as defined in Section 6.1 of [RFC8279].
3.3.5. Responder BFER TLV
The BFER replying to the request MAY include the Responder BFER TLV.
This TLV identifies the originator of BIER Echo Reply. This TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 5 | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | BFR-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: The Responder BFER TLV Format
Length A two-octet field. The value MUST be set to four.
Reserved A two-octet field. The value MUST be zeroed on
transmission and ignored on receipt.
BFR-ID A two-octet field. The BFR-ID field carries the BFR-ID of
the replying BFER. This TLV MAY be included by the Responding
BFER in the BIER Echo Reply packet.
3.3.6. Responder BFR TLV
Any transit BFR replying to the request MAY include the Responder BFR
TLV. This is used to identify the replying BFR without BFR-ID. This
TLV has the following format:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type = 6 | Length = 8 or 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Address Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ BFR-Prefix (4 or 16 bytes) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: The Responder BFD TLV Format
Length The Length field, depending on the Address Type value - 8 or
20.
Reserved A two-octet field. The value MUST be zeroed on
transmission and ignored on receipt.
Address Type A two-octet field. Set to 1 for IPv4 or 2 for IPv6.
BFR-Prefix This field carries the local BFR-Prefix of the replying
BFR. This TLV MAY be included by Responding BFR in BIER Echo
Reply packet.
3.3.7. Upstream Interface TLV
The BFR replying to the request MUST include the Upstream Interface
TLV. This TLV identifies the incoming interface and the BIER-MPLS
label in the incoming Echo Request. This TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type = 7 | Length = 8 or 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Address Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Upstream Address (4 or 16 bytes) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: The Upstream Interface TLV Format
Length The Length field, depending on the Address Type value - 8 or
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20.
Reserved A two-octet field. The value MUST be zeroed on
transmission and ignored on receipt.
Address Type A two-octet field. Set to 1 for IPv4 numbered, 2 for
IPv4 Unnumbered, 3 for IPv6 numbered, or 4 for IPv6 Unnumbered.
Upstream Address
As defined in Section 3.3.4
3.4. Multipath Entropy Data Encoding
The size of the Entropy field in the BIER header is 20 bits, as
defined in Section 2 of [RFC8296]. This encoding is the same as the
Multipath Type 9 encoding, defined in Section 3.4.1.1.1 of [RFC8029].
4. Procedures
This section describes aspects of Ping and traceroute operations.
4.1. BIER OAM Processing
A BIER OAM packet MUST be sent to the BIER control plane for OAM
processing if one of the following conditions is true:
* The receiving BFR is a BFER.
* TTL of BIER-MPLS Label (Section 2.1.1.1 [RFC8296]) expired.
The use of the Router Alert label to be deprecated as proposed in
[I-D.ietf-mpls-lspping-norao].
4.2. Per BFER ECMP Discovery
As defined in [RFC8279], BIER follows the unicast forwarding path and
allows load balancing over ECMP paths between BFIR and BFER. BIER
OAM is expected to support ECMP path discovery between a BFIR and a
given BFER and MUST support path validation and failure detection of
any particular ECMP path between BFIR and BFER.
[RFC8296] proposes the BIER header with the Entropy field that can be
leveraged to exercise all ECMP paths. The Initiator/BFIR will use a
traceroute message to query each hop about the Entropy information
for each of the downstream paths. To avoid complexity, it is
suggested that the ECMP query is performed per BFER by carrying the
required information in the BIER OAM message.
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The Initiator MUST include Multipath Entropy Data Sub-TLV in
Downstream Mapping TLV. It MUST also include the BFER in BitString
TLV to which the Multipath query is performed.
Any transit BFR will reply with Bit-masked Entropy for each
downstream path as defined in [RFC8029]
4.3. Sending BIER Echo Request
The Initiator MUST set the Message Type as 1 and Return Code as 0.
The Proto field in the OAM packet MUST be set to 0. The choice of
the Sender's Handle and Sequence Number is a local matter to the
Initiator and SHOULD increment the Sequence Number by 1 for every
subsequent Echo Request. The QTF field is set to Initiator's local
timestamp format, and the TimeStamp Sent field is set to the time
that the Echo Request is sent.
The Initiator MUST include Original SI-BitString TLV. The Initiator
MUST NOT include more than one Original SI-BitString TLV. The
Initiator infers the Set Identifier value and Sub-domain ID value
from the respective BitString that will be included in the BIER
header of the packet and includes the values in "SI" and Sub-Domain
ID fields, respectively.
In Ping mode, the Initiator MAY include Target SI-BitString TLV to
control the responding BFER(s) by listing all the BFERs from which
the Initiator expects a response. In the traceroute mode, the
Initiator MAY include Target SI-BitString TLV to control the path
trace towards any specific BFER or set of BFERs. The Initiator on
receiving a reply with the Return code "Replying BFR is the only BFER
in the header BitString" or "Replying router is one of the BFERs in
header BitString" SHOULD unset the respective BFR-id from Target SI-
BitString for any subsequent Echo Request.
The Initiator MAY include Downstream Mapping TLV (Section 3.3.4) in
the Echo Request to query additional information from transit BFRs
and BFERs. In case of ECMP discovery, the Initiator MUST include the
Multipath Entropy Data Sub-TLV and SHOULD set the Target SI-BitString
TLV carrying a specific BFER ID.
The Initiator MUST encapsulate the OAM packet with the BIER header
and MUST set the Proto as 5 and further encapsulates with BIER-MPLS
label. In ping mode, the BIER-MPLS Label TTL MUST be set to 255. In
traceroute mode, the BIER-MPLS Label TTL is set successively,
starting from 1 and MUST stop sending the Echo Request if it receives
a reply with Return code as "Replying router is the only BFER in BIER
header BitString" from all BFER listed in Target SI-BitString TLV.
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4.4. Receiving BIER Echo Request
Sending a BIER OAM Echo Request to control plane for payload
processing is triggered as mentioned in Section 4.1.
Any BFR on receiving Echo Request MUST perform the basic sanity
check. If the BFR cannot parse the OAM Dependent data payload
completely because the value in the OAM Message Length field is
incorrect, BFR MUST send Echo Reply with Return Code set to
"Malformed Echo Request received" if the OAM Message Length is
incorrect. If the packet sanity check is fine, it SHOULD initiate
the below set of variables:
Reply-Flag
This flag is initially set to 1.
Interface-I
The incoming interface on which the Echo Request was received.
This MAY be used to validate the Downstream Detailed Mapping TLV
(DDMAP) info and populate the Upstream Interface TLV.
BIER-Label-L
The BIER-MPLS Label received as the top label of the received Echo
Request. This MAY be used to validate if the packet is traversing
the desired Set Identifier and sub-domain path.
Header-H
The BIER header of the received Echo Request. It can be used to
validate the DDMAP info and to populate the Incoming SI-BitString
TLV. Also, it can be used to perform entropy calculation
considering a different field in the header and replying with
Multipath Entropy Data Sub-TLV.
BFR MUST initialize the Best-return-code variable to the null value.
BFR will populate the Interface-I with the identifier of the
interface over which the Echo Request is received, the top label in
the MPLS stack of the received Echo Request to BIER-Label-L, and the
BIER header to BIER-Header. If the received Echo Request carries
Target SI-BitString TLV, a BFR SHOULD run the boolean AND operation
between BitString in Header-H and BitString in Target SI-BitString
TLV. If the resulting BitString is all-zero, reset Reply-Flag=0 and
go to Section 4.5. Else:
* If the BIER-Label-L does not correspond to the local label
assigned for {sub-domain, BitStringLen, SI} in Original SI-
BitString TLV, Set the Best-return-code to "Set-Identifier
Mismatch" and Go to Section 4.5.
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This step allows the detection of a synchronization problem in the
upstream BFR between BIER-Label and {sub-domain, BitStringLen, SI}
that might cause an unintended packet leak between sub-domains.
* Set the Best-return-code to "One or more of the TLVsis not
supported" if any of the TLVs in the Echo Request message is not
supported. Go to Section 4.5.
* If the BitString in Header-H does not match the BitString in
Egress BitString Sub-TLV of DDMAP TLV, set the Best-return-code to
"DDMAP Mismatch" and go to Section 4.5. When there are more than
one DDMAP TLV in the received Request packet, the Downstream
Address and Downstream Interface Address should be matched with
Interface-I to identify the right DDMAP TLV and then perform the
BitString match.
This step allows the detection of a deviation between the BIER
control plane and the BIER forwarding plane in the upstream node that
may result in a forwarding loop or packet duplication.
* Set the Best-return-code to "Invalid Multipath Info Request", when
the DDMAP TLV carries Multipath Entropy Data Sub-TLV, and if the
Target SI-BitString TLV in the received Echo Request carries more
than 1 BFER id. Go to Section 4.5. Else, list the ECMP
downstream neighbors to reach BFR-id in Target SI-BitString TLV,
calculate the Entropy considering the BitString in Header-H and
Multipath Entropy Data Sub-TLV from received Echo Request. Store
the Data for each Downstream interface in a temporary variable.
Set the Best-return-code to 5 (Packet-Forward-Success) and goto
Section 4.5
This step instructs the node to calculate the Entropy Data for each
downstream interface to reach the BFER in Target SI-BitString TLV by
considering the incoming BitString and Entropy Data.
* Set the Best-return-code to "Replying router is the only BFER in
BIER header BitString", and go to Section 4.5 if the responder is
BFER and there are no more bits in the BIER header BitString left
for forwarding.
* Set the Best-return-code to "Replying router is one of the BFERs
in BIER header BitString", and include Downstream Mapping TLV if
the responder is BFER and there are more bits in BitString left
for forwarding. Also, include the Multipath information as
defined in Section 4.2 if the received Echo Request carries
Multipath Entropy Data Sub-TLV. Go to Section 4.5.
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* Set the Best-return-code to "No matching entry in the forwarding
table", if the forwarding lookup, defined in Section 6.5 of
[RFC8279] does not match any entry for the received BitString in
BIER header.
This step allows the detection of the missing BFR-id in the node's
BIER forwarding table. It is difficult to detect the absence of the
BFR-id if the Request includes more than one BFR-ids in the BitString
and so may need to include the BFER-id that is not responding to
detect such failure.
* Set the Best-return-code to "Packet-Forward-Success", and include
Downstream Mapping TLV. Go to Section 4.5.
4.5. Sending Echo Reply
If Reply-Flag=0, BFR MUST release the variables and MUST NOT send any
response to the Initiator. If Reply-Flag=1, proceed as below:
The Responder BFR SHOULD include the BitString from Header-H to
Incoming SI-BitString TLV and include the Set ID, Sub-domain ID and
BS Len that corresponds to BIER-Label-L. Responder BFR SHOULD
include the Upstream Interface TLV and populate the address from
Interface-I.
When the Best-return-code is "Replying BFR is one of the BFERs in
header BitString", it MUST include Responder BFER TLV.
If the received Echo Request had DDMAP with Multipath Entropy Data
Sub-TLV, Responder BFR MUST include DDMAP as defined in
Section 3.3.4 for each outgoing interface over which the packet
will be replicated and include the respective Multipath Entropy
Data Sub-TLV. For each outgoing interface, the respective Egress
BitString MUST be included in DDMAP TLV.
If the received Echo Request had DDMAP without Multipath Entropy
Data Sub-TLV, Responder BFR MUST include DDMAP as defined in
Section 3.3.4 for each outgoing interface over which the packet
will be replicated. For each outgoing interface, respective
Egress BitString MUST be included in DDMAP TLV.
When the Best-return-code is "Replying BFR is the only BFER in header
BitString", it MUST include Responder BFER TLV.
The Responder MUST set the Message Type as 2 and Return Code as Best-
return-code. The Proto field MUST be set to 0.
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The Echo Reply can be sent as BIER-encapsulated, or IP/UDP
encapsulated, depending on the Reply Mode in the received Echo
Request. When the Reply Mode in the received Echo Request is set to
3, Responder appends the BIER header listing the BitString with BFIR
ID (from Header- H), sets the Proto to 5, and sets the BFIR as 0.
When the Reply Mode in the received Echo Request is set to 2,
Responder encapsulates with the IP/UDP header. The UDP destination
port MUST be set to TBD1 (Section 5.1), and the source port MAY be
set to TBD1 or other value selected from the Dynamic range of port
numbers. The source IP is any local address of the responder, and
the destination IP is derived from the BFIR-id of the BIER header
[RFC8296] of the received Echo Request.
4.6. Receiving Echo Reply
The Initiator, upon receiving the Echo Reply, will use the Sender's
Handle to match with Echo Request sent. If no match is found, the
Initiator MUST ignore the Echo Reply.
If receiving Echo Reply has Downstream Mapping, the Initiator SHOULD
copy the same to subsequent Echo Request(s).
If one of the Echo Reply is received with Return Code as "Replying
BFR is one of the BFERs in header BitString", it SHOULD reset the
BFR- id of the responder from Target SI-BisString TLV in subsequent
Echo Request. This step helps avoid any BFR that is both BFER and
transit BFR to respond with Echo Reply continuously.
5. IANA Considerations
The terms used in the IANA Considerations below are intended to be
consistent with [RFC8126].
5.1. UDP Port Number
This document requests a UDP port TBD1 to be allocated by IANA for
BIER Echo.
5.2. BIER OAM Parameters
IANA is requested to create and maintain the "BIER OAM Parameters"
registry containing the sub-registries listed below.
5.3. BIER OAM Message Type
IANA is requested to create in the BIER OAM Parameters registry a
sub-registry as follows:
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Sub-registry Name: BIER OAM Message Type.
Assignment Policy:
2-31 IETF Review
32-62 First Come, First Served
Reference: [this document]
+========+==============================+===============+
| Value | Description | Reference |
+========+==============================+===============+
| 0 | Reserved | This document |
+--------+------------------------------+---------------+
| 1 | BIER Echo Request/Echo Reply | This document |
+--------+------------------------------+---------------+
| 2 - 31 | Unassigned | This document |
+--------+------------------------------+---------------+
| 32-62 | Unassigned | This document |
+--------+------------------------------+---------------+
| 63 | Reserved | This document |
+--------+------------------------------+---------------+
Table 1: BIER OAM Message Type
5.4. BIER Echo Request/Echo Reply Parameters
IANA is requested to create in the BIER OAM registry the sub-registry
BIER Echo Request/Echo Reply Parameters.
5.4.1. BIER Echo Request/Echo Reply Message Types
IANA is requested to create in the BIER Echo Request/Echo Reply
Parameters the BIER Echo Request/Echo Reply Message Types sub-
registry as follows:
Sub-registry Name: BIER Echo Request/Echo Reply Message Types
Assignment Policy:
3 - 175 IETF Review
176 - 239 First Come, First Served
Reference: [this document]
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+===========+===================+===============+
| Value | Description | Reference |
+===========+===================+===============+
| 0 | Reserved | This document |
+-----------+-------------------+---------------+
| 1 | BIER Echo Request | This document |
+-----------+-------------------+---------------+
| 2 | BIER Echo Reply | This document |
+-----------+-------------------+---------------+
| 3 - 175 | Unassigned | This document |
+-----------+-------------------+---------------+
| 176 - 239 | Unassigned | This document |
+-----------+-------------------+---------------+
| 240 - 251 | Experimental | This document |
+-----------+-------------------+---------------+
| 252 - 254 | Private Use | This document |
+-----------+-------------------+---------------+
| 255 | Reserved | This document |
+-----------+-------------------+---------------+
Table 2: BIER Echo Request/Echo Reply Message
Types
5.4.2. BIER Echo Reply Modes
IANA is requested to create in the BIER Echo Request/Echo Reply
Parameters registry the new sub-registry as follows:
Sub-registry Name: BIER Echo Reply Mode
Assignment Policy:
8 - 175 IETF Review
176 - 239 First Come, First Served
Reference: [this document]
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+===========+===================================+===============+
| Value | Description | Reference |
+===========+===================================+===============+
| 0 | Reserved | This document |
+-----------+-----------------------------------+---------------+
| 1 | Do Not Reply | This document |
+-----------+-----------------------------------+---------------+
| 2 | Reply via an IPv4/IPv6 UDP Packet | This document |
+-----------+-----------------------------------+---------------+
| 3 | Reply via BIER packet | This document |
+-----------+-----------------------------------+---------------+
| 4 - 175 | Unassigned | This document |
+-----------+-----------------------------------+---------------+
| 176 - 239 | Unassigned | This document |
+-----------+-----------------------------------+---------------+
| 240 - 251 | Experiemntal | This document |
+-----------+-----------------------------------+---------------+
| 252 - 254 | Private Use | This document |
+-----------+-----------------------------------+---------------+
| 255 | Reserved | This document |
+-----------+-----------------------------------+---------------+
Table 3: SFC Echo Reply Modes
5.4.3. BIER Echo Return Codes
IANA is requested to create in the BIER Echo Request/Echo Reply
Parameters registry the new sub-registry as follows:
Sub-registry Name: BIER Echo Return Codes
Assignment Policy:
9 - 191 IETF Review
192 - 251 First Come, First Served
Reference: [this document]
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+=========+=================================+===============+
| Value | Description | Reference |
+=========+=================================+===============+
| 0 | No Return Code | This document |
+---------+---------------------------------+---------------+
| 1 | Malformed Echo Request received | This document |
+---------+---------------------------------+---------------+
| 2 | One or more of the TLVs is not | This document |
| | supported | |
+---------+---------------------------------+---------------+
| 3 | Replying BFR is the only BFER | This document |
| | in header BitString | |
+---------+---------------------------------+---------------+
| 4 | Replying BFR is one of the | This document |
| | BFERs in header BitString | |
+---------+---------------------------------+---------------+
| 5 | Packet-Forward-Success | This document |
+---------+---------------------------------+---------------+
| 6 | Invalid Multipath Info Request | This document |
+---------+---------------------------------+---------------+
| 7 | Unassigned | This document |
+---------+---------------------------------+---------------+
| 8 | No matching entry in the | This document |
| | forwarding table | |
+---------+---------------------------------+---------------+
| 9 | Set-Identifier Mismatch | This document |
+---------+---------------------------------+---------------+
| 10 | DDMAP Mismatch | This document |
+---------+---------------------------------+---------------+
| 11 - | Unassigned | This document |
| 191 | | |
+---------+---------------------------------+---------------+
| 192-251 | Unassigned | This document |
+---------+---------------------------------+---------------+
| 252-254 | Private Use | This document |
+---------+---------------------------------+---------------+
| 255 | Reserved | This document |
+---------+---------------------------------+---------------+
Table 4: BIER Echo Return Codes
5.5. TLVs
IANA is requested to create in the BIER OAM registry a sub-registry
for the Type field of top-level TLVs as well as for any associated
sub-TLVs. Note that the meaning of a sub-TLV is scoped by the TLV.
The number of spaces for the sub-TLVs of various TLVs is independent.
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The valid range for TLVs and sub-TLVs is 0-65535. Assignments in the
ranges 0-16383 and 32768-49161 are made via Standards Action as
defined in [RFC8126]; assignments in the ranges 16384-31743 and
49162-64511 are made via "Specification Required"; values in the
ranges 31744-32767 and 64512-65535 are for Private Use and MUST NOT
be allocated.
If a TLV or sub-TLV has a Type that falls in the range of Private
Use, the Length MUST be at least 4, and the first four octets MUST be
an SMI Private Enterprise Number that identifies the user, in network
octet order. The rest of the Value field is private to the user.
The TLVs and Sub-TLVs defined in this document are not limited to
Echo Request or Reply message types are applicable to other message
types. The TLVs and Sub-TLVs requested by this document for the IANA
consideration are the following:
Type Sub-Type Value Field
------- -------- -----------
1 Original SI-BitString
2 Target SI-BitString
3 Incoming SI-BitString
4 Downstream Mapping
4 1 Multipath Entropy Data
4 2 Egress BitString
5 Responder BFER
6 Responder BFR
7 Upstream Interface
6. Security Considerations
The security consideration for BIER Ping is similar to ICMP [RFC0792]
or LSP Ping [RFC8029], [RFC6425]. As with ICMP or LSP Ping, BFR can
be exposed to Denial-of-Service (DoS) attacks, and it is RECOMMENDED
to regulate the BIER Ping packet flow to the control plane. A rate
limiter SHOULD be applied to avoid any attack. Although using BIER
Echo Request in a DoS amplification attack is theoretically possible,
spoofing BFIR ID in the BIER Header presents itself as a serious
challenge. As a result, this threat is not a big concern.
As with ICMP or LSP Ping, a traceroute can be used to obtain network
information. It is RECOMMENDED that the implementation checks the
integrity of BFIR of the Echo messages against any locally secured
list before processing the message further.
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7. Acknowledgement
The authors would like to thank Antoni Przygienda, Eric Rosen, Faisal
Iqbal, Jeffrey (Zhaohui) Zhang, and Shell Nakash for their review and
comments.
The authors would like to thank Mankamana Mishra for his thorough
review and comments.
8. References
8.1. 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>.
[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>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<https://www.rfc-editor.org/info/rfc5905>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
Explicit Replication (BIER)", RFC 8279,
DOI 10.17487/RFC8279, November 2017,
<https://www.rfc-editor.org/info/rfc8279>.
[RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation
for Bit Index Explicit Replication (BIER) in MPLS and Non-
MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January
2018, <https://www.rfc-editor.org/info/rfc8296>.
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[RFC6425] Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A.,
Yasukawa, S., and T. Nadeau, "Detecting Data-Plane
Failures in Point-to-Multipoint MPLS - Extensions to LSP
Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011,
<https://www.rfc-editor.org/info/rfc6425>.
[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>.
[IEEE.1588.2008]
"Standard for a Precision Clock Synchronization Protocol
for Networked Measurement and Control Systems",
IEEE Standard 1588, March 2008.
8.2. Informative References
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, DOI 10.17487/RFC0792, September 1981,
<https://www.rfc-editor.org/info/rfc792>.
[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>.
[I-D.ietf-mpls-lspping-norao]
Kompella, K., Bonica, R., and G. Mirsky, "Deprecating the
Use of Router Alert in LSP Ping", Work in Progress,
Internet-Draft, draft-ietf-mpls-lspping-norao-01, 11 March
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
mpls-lspping-norao-01>.
Authors' Addresses
Nagendra Kumar
Cisco Systems, Inc.
7200 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: naikumar@cisco.com
Carlos Pignataro
Cisco Systems, Inc.
7200 Kit Creek Road
Research Triangle Park, NC 27709-4987
US
Kumar, et al. Expires 20 November 2023 [Page 29]
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Email: cpignata@cisco.com
Nobo Akiya
Big Switch Networks
Japan
Email: nobo.akiya.dev@gmail.com
Lianshu Zheng
Individual Contributor
China
Email: veronique_cheng@hotmail.com
Mach Chen
Huawei Technologies
Email: mach.chen@huawei.com
Greg Mirsky
Ericsson
Email: gregimirsky@gmail.com
Kumar, et al. Expires 20 November 2023 [Page 30]