Internet DRAFT - draft-ietf-pwe3-oam-config
draft-ietf-pwe3-oam-config
PWE3 Working Group F. Zhang, Ed.
Internet-Draft B. Wu, Ed.
Intended status: Standards Track ZTE Corporation
Expires: February 25, 2013 E. Bellagamba, Ed.
Ericsson
August 24, 2012
Label Distribution Protocol Extensions for Proactive Operations,
Administration and Maintenance Configuration of Dynamic MPLS Transport
Profile PseudoWire
draft-ietf-pwe3-oam-config-01
Abstract
This document specifies extensions to the Label Distribution Protocol
(LDP) to configure and control proactive Operations, Adminstration
and Maintenance (OAM) functions, suitable for dynamic Single-Segment
PseudoWire (SS-PW) and Multi-Segment PseudoWire (MS-PW).
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 February 25, 2013.
Copyright Notice
Copyright (c) 2012 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Analysis of PW OAM Configuration Extended by MPLS-TP . . . . . 4
3.1. Continuity Check, Connectivity Verification and Remote
Defect Indication . . . . . . . . . . . . . . . . . . . . 4
3.2. Performance Monitoring Loss/Delay . . . . . . . . . . . . 5
3.3. FMS . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.4. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . 6
4. PW OAM Configuration Procedures . . . . . . . . . . . . . . . 6
4.1. OAM Configuration for MS-PW . . . . . . . . . . . . . . . 7
4.1.1. Establishment of OAM Entities and Functions . . . . . 7
4.1.2. Adjustment of OAM Parameters . . . . . . . . . . . . . 8
4.1.3. Deleting OAM Entities . . . . . . . . . . . . . . . . 9
4.2. OAM Configuration for SS-PW . . . . . . . . . . . . . . . 9
5. LDP extensions . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. MPLS-TP PW OAM Administration TLV . . . . . . . . . . . . 10
5.2. MPLS-TP PW OAM Configuration TLV . . . . . . . . . . . . . 10
5.2.1. BFD Configuration sub-TLV . . . . . . . . . . . . . . 12
5.2.1.1. Local Discriminator sub-TLV . . . . . . . . . . . 13
5.2.1.2. Negotiation Timer Parameters sub-TLV . . . . . . . 13
5.2.1.3. BFD Authentication sub-TLV . . . . . . . . . . . . 15
5.2.2. Performance Monitoring sub-TLV . . . . . . . . . . . . 15
5.2.2.1. MPLS-TP PW PM Loss TLV . . . . . . . . . . . . . . 16
5.2.2.2. MPLS-TP PW PM Delay TLV . . . . . . . . . . . . . 17
5.2.3. MPLS-TP PW FMS TLV . . . . . . . . . . . . . . . . . . 18
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
6.1. OAM Configuration Errors . . . . . . . . . . . . . . . . . 19
7. Security Considerations . . . . . . . . . . . . . . . . . . . 20
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 20
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.1. Normative references . . . . . . . . . . . . . . . . . . . 20
9.2. Informative References . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
MPLS Pseudowire (PW) is defined in [RFC3985] and [RFC5659], which
provides for emulated services over an MPLS Packet Switched Network
(PSN). MPLS Transport Profile (MPLS-TP) describes a profile of MPLS
that enables operational models typical in transport networks, while
providing additional Operations, Administration and Maintenance
(OAM), survivability and other maintenance functions not previously
supported by IP/MPLS. The corresponding requirements are defined in
[RFC5860].
The MPLS-TP OAM mechanisms that are operated to meet transport
requirements are described in [RFC6371], categorized into proactive
and on-demand monitoring. Proactive monitoring refers to OAM
operations that are either configured to be carried out periodically
and continuously or preconfigured to act on certain events such as
alarm signals. In contrast, on-demand monitoring is initiated
manually and for a limited amount of time, usually for operations
such as diagnostics to investigate into a defect condition.
The Network Management System (NMS) or Label Switched Path (LSP) Ping
[I-D.ietf-mpls-lsp-ping-mpls-tp-oam-conf] is used to configure these
OAM functionalities if a control plane is not instantiated. But if
the control plane is used, it must support the configuration and
modification of OAM maintenance points as well as the activation/
deactivation of OAM when the transport path or transport service is
established or modified [RFC5654].
This document specifies the extensions to the LDP protocol to
configure and bootstrap proactive PW OAM functions, suitable for
Point to Point (P2P) SS-PW and MS-PW. The extensions to Point to
Multi-Point (P2MP) PW will be studied in the future.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2.1. Acronyms
AC: Attachment Circuit
AIS: Alarm indication signal
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BFD: Bidirectional Forwarding Detection
CC: Continuity Check
CV: Connectivity Verification
DM: Delay Measurement
FEC: Forwarding Equivalence Class
FMS: Fault Management Signal
ICMP: Internet Control Message Protocol
G-ACh: Generic Associated Channel
LDI: Link Down Indication
LDP: Label Distribution Protocol
LKR: Lock Reporting
LM: Loss Measurement
LSP: Label Switched Path
ME: Maintenance Entity
MEG: Maintenance Entity Group
MEP: Maintenance Entity Group End Point
MIP: Maintenance Entity Group Intermediate Point
MPLS-TP: MPLS Transport Profile
MS-PW: Multi-Segment PseudoWire
NMS: Network Management System
OAM: Operations, Adminstration and Maintenance
P2MP: Point to Multi-Point
PE: Provider Edge
PHB: Per-Hop Behavior
PM: Performance Monitoring
PSN: Packet Switched Network
PW: PseudoWire
S-PE: Switching Provider Edge
SPME: Sub-Path Maintenance Entity
SS-PW: Single-Segment Pseudo Wire
T-PE: Terminating Provider Edge
TLV: Type Length Value
VCCV: Virtual Circuit Connectivity Verification
3. Analysis of PW OAM Configuration Extended by MPLS-TP
3.1. Continuity Check, Connectivity Verification and Remote Defect
Indication
The Proactive CC, CV and Remote Defect Indication (RDI) functions of
MPLS-TP are based on the extensions to BFD [RFC6428], which addresses
the proactive CV gap that VCCV BFD does not support. The BFD packets
can be encapsulated by IP or non-IP in G-ACh, and operate in
coordinated or independent mode.
Timer negotiation, such as Transmitter (TX)/Receiver (RX) interval
can be performed in subsequent BFD control messages [RFC5880] or
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directly in the LSP ping configuration messages, but it also can be
gotten by control plane signaling [RFC6371].
The use of the VCCV control channel provides the context, based on
the MPLS-PW label, required to bind and bootstrap the BFD session to
a particular PW, so local discriminator values are not exchanged
[RFC6669]. However, in order to identify certain extreme cases of
mis-connectivity and fulfill the requirements that the BFD mechanism
MUST be the same for LSP, Single Segment Pseudowire (SS-PW), Multi
Segment Pseudowire (MS-PW) and Section as well as for Sub-path
Maintenance Element (SPME), BFD might still need to use discriminator
values to identify the connection being verified at both ends of the
PW. The discriminator values can be statically configured, or
signaled via LSP Ping or LDP extensions defined in this document.
Per-hop Behavior (PHB), which identifies the per-hop behavior of BFD
packet, SHOULD be configured as well. This permits the verification
of correct operation of Quality of Serivce (QoS) queuing as well as
connectivity.
When BFD Control packets are transported in the G-ACh they are not
protected by any end-to-end checksum, only lower-layers are providing
error detection/correction. A single bit error, e.g. a flipped bit
in the BFD State field could cause the receiving end to wrongly
conclude that the link is down and in turn trigger protection
switching. To prevent this from happening the "BFD Configuration
sub-TLV" has an Integrity flag that when set enables BFD
Authentication using Keyed SHA1 with an empty key (all 0s) [RFC5880].
This would make every BFD Control packet carry an SHA1 hash of itself
that can be used to detect errors.
If BFD Authentication using a shared key / password is desired (i.e.
actual authentication not only error detection) the "BFD
Authentication sub-TLV" MUST be included in the "BFD Configuration
sub-TLV". The "BFD Authentication sub-TLV" is used to specify which
authentication method that should be used and which shared key /
password that should be used for this particular session. How the
key exchange is performed is out of scope of this document.
3.2. Performance Monitoring Loss/Delay
Performance monitoring (PM) of PWs, especially for packet Loss
Measurement (LM) and packet Delay Measurement (DM), are specified in
[RFC6374], [RFC6375].
When configuring Performance monitoring functionalities it can be
chosen either the default configuration (by only setting the
respective flags in the "MPLS-TP PW OAM Configuration TLV") or a
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customized configuration (by including the respective MPLS-TP PW PM
Loss and/or Delay sub-TLVs).
By setting the PM Loss flag in the "MPLS-TP PW OAM Configuration TLV"
and including the "MPLS-TP PW PM Loss sub-TLV" one can configure the
measurement interval and loss threshold values for triggering
protection.
Delay measurements are configured by setting PM Delay flag in the
"MPLS-TP PW OAM Configuration TLV" and including the "MPLS-TP PW PM
Loss sub-TLV" one can configure the measurement interval and the
delay threshold values for triggering protection.
3.3. FMS
Fault Management Signals (FMS) are specified in [RFC6428], with which
a server PW can notify client PWs about various fault conditions to
suppress alarms or to be used as triggers for actions in the client
PWs. The following signals are defined: Alarm Indication Signal
(AIS), Link Down Indication (LDI) and Lock Reporting (LKR).
For each MEP of each Maintenance Entity Group (MEG), enabling/
disabling the generation of FMS packets, the transmitted period and
PHB SHOULD be configured. This can be done independently, and the
values of configured parameters can be different, but for easy
maintenance, these setting SHOULD be consistent.
3.4. Conclusion
According to the analysis above, LDP needs to be extended to
configure and bootstrap proactive PW OAM functions, such as, CC-CV-
RDI, PM Loss/Delay, FMS. In this way, OAM configuration is bound to
PW signaling, avoiding two separate management/configuration steps
(PW establishment followed by OAM configuration) which would
increases delay, processing and more importantly may be prune to mis-
configuration errors.
4. PW OAM Configuration Procedures
A PE may play an active or passive role in the signaling of the PW.
There exist two situations:
a) Active/active: both PEs of a PW are active (SS-PW), they select PW
OAM configuration parameters and send with the Label Mapping message
to each other independently.
b) Active/passive: one PE is active and the others are passive
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(MS-PW). The active/passive role election is defined in Section
7.2.1 of [RFC6073] and applies here, this document does not define
any new role election procedures.
The general rules of OAM configuration procedures are mostly
identical between MS-PW and SS-PW, except that SS-PW does not need to
configure MIP function and the Mapping message are sent out
independently. Section 4.1 takes MS-PW as an example to describe the
general OAM configuration procedures. As for SS-PW, the specific
differences would be addressed in section 4.2.
4.1. OAM Configuration for MS-PW
4.1.1. Establishment of OAM Entities and Functions
Assuming there is one PW that needs to be setup between T-PE1 and
T-PE2, across S-PE1 and S-PE2. OAM functions must be setup and
enabled in the appropriate order so that spurious alarms can be
avoided.
+-------+ +-------+ +-------+ +-------+
| | | | | | | |
| A|--------|B C|--------|D E|--------|F |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
T-PE1 S-PE1 S-PE2 T-PE2
Figure 1: MS-PW OAM Configuration Scheme
Fist of all, T-PE1 MUST setup the OAM sink function to be prepared to
receive OAM messages but MUST suppress any OAM alarms (e.g., due to
missing or unidentified OAM messages). The Mapping message MUST be
sent with the "OAM Alarms Enabled" cleared and "OAM MIP Entities
desired" set in the MPLS-TP PW OAM Administation TLV.
When the Mapping message arrives at the downstream S-PEs, such as
S-PE1 and S-PE2, they MUST establish and configure MIP entities
according to the set "I"flag in the MPLS-TP PW OAM Administration
TLV. If failure, a Notification message SHOULD be sent, with a
Status Code set to "MIP Configuration Failure". If OAM entities are
established successfully, the middle points (S-PE1 and S-PE2) MUST
forward the Mapping message downstream, the endpoint (T-PE2) MUST set
the OAM Source function and MUST be prepared to Send OAM messages.
The same rules are applied to the reverse direction (from T-PE2 to
T-PE1), that is to say, T-PE2 needs to setup the OAM sink function to
be prepared to receive OAM messages but MUST suppress any OAM alarms
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(e.g., due to missing or unidentified OAM messages). The Mapping
message MUST be sent with the "OAM Alarms Enabled" cleared, "OAM MIP
Entities desired" set in the MPLS-TP PW OAM Administration TLV. When
T-PE1 receives the Mapping message, it completes any pending OAM
configuration and enables the OAM source function to send OAM
messages.
After this round, OAM entities are established and configured for the
PW and OAM messages MAY already be exchanged, and OAM alarms can now
be enabled. The T-PE nodes (T-PE1 and T-PE2), while still keeping
OAM alarms disabled send a Notification message with "OAM Alarms
Enabled" PW status flag set, and enable the OAM alarms after
processing the Notification message. At this point, data-plane OAM
is fully functional, and the MPLS-TP OAM PW configuration TLV MAY be
omitted in subsequent Notification messages
The PW MAY be setup with OAM entities right away with the first
signaling, as described above, but a PW MAY be signaled and
established without OAM configuration first, and OAM entities may be
added later. This can be done by sending a Notification message with
the related configuration parameters subsequently.
4.1.2. Adjustment of OAM Parameters
There may be a need to change the parameters of an already
established and configured OAM function during the lifetime of the
PW. To do so the T-PE nodes need to send a Notification message with
the updated parameters. OAM parameters that influence the content
and timing of OAM messages and identify the way OAM defects and
alarms are derived and generated. Hence, to avoid spurious alarms,
it is important that both sides, OAM sink and source, are updated in
a synchronized way. Firstly, the alarms of the OAM sink function
should be suppressed and only then should expected OAM parameters be
adjusted. Subsequently, the parameters of the OAM source function
can be updated. Finally, the alarms of the OAM sink side can be
enabled again.
In accordance with the above operation, T-PE1 MUST send a
Notification message with "OAM Alarms Enabled" cleared and including
the updated MPLS-TP PW OAM Configuration TLV corresponding to the new
parameter settings. The initiator (T-PE1) MUST keep its OAM sink and
source functions running unmodified, but it MUST suppress OAM alarms
after the updated Notification message is sent. The receiver (T-PE2)
MUST firstly disable all OAM alarms, then update the OAM parameters
according to the information in the Notification message and reply
with a Notification message acknowledging the changes by including
the MPLS-TP PW OAM Configuration TLV. Note that the receiving side
has the possibility to adjust the requested OAM configuration
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parameters and reply with and updated MPLS-TP PW OAM Configuration
TLV in the Notification message, reflecting the actually configured
values. However, in order to avoid an extensive negotiation phase,
in the case of adjusting already configured OAM functions, the
receiving side SHOULD NOT update the parameters requested in the
Notification message to an extent that would provide lower
performance than what has been configured previously.
The initiator (T-PE1) MUST only update its OAM sink and source
functions when it has received the Notification message from the
peer. After the OAM parameters are updated and OAM is running
according the new parameter settings, OAM alarms are still disabled,
so a subsequent Notification messages exchanges with "OAM Alarms
Enabled" flag set are needed to enable OAM alarms again.
4.1.3. Deleting OAM Entities
In some cases it may be useful to remove some or all OAM entities and
functions from one PW without actually tearing down the connection.
To avoid any spurious alarm, the following procedure should be
followed:
The T-PE nodes disable OAM alarms and SHOULD send Notification
message to each other with "OAM Alarms Enabled" cleared but unchanged
OAM configuration and without the MPLS-TP PW OAM Configuration TLV.
After that, T-PE1 (T-PE2) SHOULD delete OAM source functions, then
send a Notification message with "OAM MIP Entities desired" cleared.
While T-PE2 (T-PE1) deletes OAM sink function, S-PE1 and S-PE2 delete
MIP configuration when they receive the Notification message with
"OAM MIP Entities desired" cleared.
Alternatively, if only some OAM functions need to be removed, the
T-PE node sends the Notification message with the updated OAM
Configuration TLV. Changes between the contents of the previously
signaled OAM Configuration TLV and the currently received TLV
represent which functions SHOULD be removed/added.
4.2. OAM Configuration for SS-PW
Assuming there is one PW that needs to be setup between T-PE1 and
T-PE2.
If the receiving PE (T-PE2) have initiated the MPLS-TP PW OAM
configuration request to the other PE (T-PE1), it MUST compare its
AII against T-PE1's. If it is numerically lower, will reply a
Notification message with the updated "MPLS-TP PW OAM Configuration
TLV", and the Status Code set to "Wrong MPLS-TP PW OAM Configuration
TLV".
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On the other hand, if the T-PE2's AII is numerically higher than
T-PE1's, it MUST reply a Notification message with Status Code set to
"Rejected MPLS-TP PW OAM Configuration TLV".
5. LDP extensions
Below, LDP extensions to configure proactive MPLS-TP PW OAM functions
are defined.
5.1. MPLS-TP PW OAM Administration TLV
The format of the MPLS-TP PW OAM Administration TLV is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Type (TBD) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I|A| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MPLS-TP PW OAM Administration TLV
One bit "I" (0, IANA to assign): "OAM MIP Entities Desired" is
allocated. If the "OAM MIP entities desired" bit is set, it is
indicating that the establishment of OAM MIP entities is required at
every transit node of the signaled PW. If the establishment of a MIP
is not supported, a Notification message MUST be sent with Status
Code set to "MIP Configuration Failure".
One bit "A" (1, IANA to assign): "OAM Alarms Enabled" is allocated.
If the "OAM Alarms Enabled" bit is set, it is indicating that the
T-PE needs to enable OAM alarms.
Reserved (2-31 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt.
5.2. MPLS-TP PW OAM Configuration TLV
The "MPLS-TP PW OAM Configuration TLV" is depicted in the following
figure. It may be carried in the Mapping and Notification messages,
just following the PW Status TLV.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Type (TBD) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|C|V|L|D|F| OAM Function Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub-TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MPLS-TP PW OAM Configuration TLV
The "MPLS-TP PW OAM Configuration TLV" contains a number of flags
indicating which OAM functions should be activated as well as OAM
function specific sub-TLVs with configuration parameters for the
particular functions.
Type: indicates a new type: the MPLS-TP PW OAM Configuration TLV
(IANA to assign).
Length: the length of the OAM Function Flags field including the
total length of the sub-TLVs in octets.
OAM Function Flags: a bitmap numbered from left to right as shown in
the figure.
These flags are defined in this document:
OAM Function Flag bit# Description
--------------------- ---------------------------
0 (C) Continuity Check (CC)
1 (V) Connectivity Verification (CV)
2 (L) Performance Monitoring/Loss (PM/Loss)
3 (D) Performance Monitoring/Delay (PM/Delay)
4 (F) Fault Management Signals (FMS)
5-31 Reserved (set all to 0s)
Sub-TLVs corresponding to the different flags are as follows.
o "BFD Configuration sub-TLV", which MUST be included if the CC
and/or the CV OAM Function flag is set. Furthermore, if the CV
flag is set, the CC flag MUST be set at the same time.
o "Performance Monitoring sub-TLV", which MUST be included if the
PM/Loss OAM Function flag is set.
o "MPLS-TP PW FMS sub-TLV", which MAY be included if the FMS OAM
Function flag is set. If the "MPLS-TP PW FMS sub-TLV" is not
included, default configuration values are used.
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5.2.1. BFD Configuration sub-TLV
The "BFD Configuration sub-TLV is defined for BFD specific
configuration parameters, which accommodates generic BFD OAM
information and carries sub-TLVs.
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 Conf. Type (1) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Vers.| PHB |N|S|I|G|U|A| Reserved (set to all 0s) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BFD Configuration sub-TLV
Type: indicates a new type, the "BFD Configuration sub-TLV" (IANA to
define, suggested value 1).
Length: indicates the length of the TLV including sub-TLVs but
excluding the Type and Length field, in octets.
Version: identifies the BFD protocol version. If a node does not
support a specific BFD version, a Notification message MUST be
generated with Status Code set to "Unsupported OAM Version".
PHB: Identifies the Per-Hop Behavior (PHB) to be used for periodic
continuity monitoring messages.
BFD Negotiation (N): If set timer negotiation/re-negotiation via BFD
Control Messages is enabled, when cleared it is disabled.
Symmetric session (S): If set the BFD session MUST use symmetric
timing values.
Integrity (I): If set BFD Authentication MUST be enabled. If the
"BFD Configuration sub-TLV" does not include a "BFD Authentication
sub-TLV" the authentication MUST use Keyed SHA1 with an empty pre-
shared key (all 0s).
Encapsulation Capability (G): if set, it shows the capability of
encapsulating BFD messages into G-Ach channel without IP/UDP headers.
If both the G bit and U bit are set, configuration gives precedence
to the G bit.
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Encapsulation Capability (U): if set, it shows the capability of
encapsulating BFD messages into G-Ach channel with IP/UDP headers.
If both the G bit and U bit are set, configuration gives precedence
to the G bit.
Operation mode (A): if set, it configures BFD in the associated mode.
If it is not set it configures BFD in independent mode.
Reserved: Reserved for future specification and set to 0.
The "BFD Configuration sub-TLV" MUST include the following sub-TLVs
in the Mapping message:
o "Local Discriminator sub-TLV".
o "Negotiation Timer Parameters sub-TLV" if the N flag is cleared.
5.2.1.1. Local Discriminator sub-TLV
The "Local Discriminator sub-TLV" is carried as a sub-TLV of the "BFD
Configuration sub-TLV" and is depicted below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lcl. Discr. Type (1) (IANA) | Length (4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Local Discriminator sub-TLV
Type: indicates a new type, the "Local Discriminator sub-TLV" (IANA
to define, suggested value 1).
Length: indicates the TLV total length in octets (4).
Local Discriminator: A unique, nonzero discriminator value generated
by the transmitting system and referring to itself, used to
demultiplex multiple BFD sessions between the same pair of systems.
5.2.1.2. Negotiation Timer Parameters sub-TLV
The "Negotiation Timer Parameters sub-TLV" is carried as a sub-TLV of
the "BFD Configuration sub-TLV" and is depicted below.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timer Neg. Type (2) (IANA) | Length (16) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Acceptable Min. Asynchronous TX interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Acceptable Min. Asynchronous RX interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Echo TX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Negotiation Timer Parameters sub-TLV
Type: indicates a new type, the "Negotiation Timer Parameters sub-
TLV" (IANA to define, suggested value 2).
Length: indicates the TLV total length in octets (16).
Acceptable Min. Asynchronous TX interval: in case of S (symmetric)
flag set in the "BFD Configuration" TLV, it expresses the desired
time interval (in microseconds) at which the T-PE initiating the
signaling intends to both transmit and receive BFD periodic control
packets. If the receiving T-PE can not support such value, it is
allowed to reply back with an interval greater than the one proposed.
In case of S (symmetric) flag cleared in the "BFD Configuration sub-
TLV", this field expresses the desired time interval (in
microseconds) at which T-PE intends to transmit BFD periodic control
packets in its transmitting direction.
Acceptable Min. Asynchronous RX interval: in case of S (symmetric)
flag set in the "BFD Configuration sub-TLV", this field MUST be equal
to "Acceptable Min. Asynchronous TX interval" and has no additional
meaning respect to the one described for "Acceptable Min.Asynchronous
TX interval".
In case of S (symmetric) flag cleared in the "BFD Configuration sub-
TLV", it expresses the minimum time interval (in microseconds) at
which T-PE can receive BFD periodic control packets. In case this
value is greater than the "Acceptable Min. Asynchronous TX interval"
received from the other T-PE, such T-PE MUST adopt the interval
expressed in this "Acceptable Min. Asynchronous RX interval".
Required Echo TX Interval: the minimum interval (in microseconds)
between received BFD Echo packets that this system is capable of
supporting, less any jitter applied by the sender as described in
[RFC5880] sect. 6.8.9. This value is also an indication for the
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receiving system of the minimum interval between transmitted BFD Echo
packets. If this value is zero, the transmitting system does not
support the receipt of BFD Echo packets. If the receiving system can
not support this value a Notification MUST be generated with Status
Code set to "Unsupported BFD TX Echo rate interval". By default the
value is set to 0.
5.2.1.3. BFD Authentication sub-TLV
The "BFD Authentication sub-TLV" is carried as a sub-TLV of the "BFD
Configuration sub-TLV" and is depicted below.
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 Auth. Type (3) (IANA) | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auth Type | Auth Key ID | Reserved (0s) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BFD Authentication sub-TLV
Type: indicates a new type, the "BFD Authentication sub-TLV" (IANA to
define, suggested value 3).
Length: indicates the TLV total length in octets (8).
Auth Type: indicates which type of authentication to use. The same
values as are defined in section 4.1 of [RFC5880] are used.
Auth Key ID: indicates which authentication key or password
(depending on Auth Type) should be used. How the key exchange is
performed is out of scope of this document.
Reserved: Reserved for future specification and set to 0.
5.2.2. Performance Monitoring sub-TLV
If the "MPLS-TP PW OAM Configuration TLV" has either the L (Loss), D
(Delay) flag set, the "Performance Monitoring sub-TLV" MUST be
present.
In case the values need to be different than the default ones the
"MPLS-TP PW PM Loss sub-TLV, "MPLS-TP PW PM Delay sub-TLV" MAY be
included:
o "MPLS-PW PM Loss sub-TLV" if the L flag is set in the "MPLS-TP PW
OAM Configuration TLV";
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o "MPLS-PW PM Dealy sub-TLV" if the D flag is set in the "MPLS-TP PW
OAM Configuration TLV ".
The "Performance Monitoring sub-TLV" depicted below is carried as a
sub-TLV of the "MPLS-TP PW OAM Configuration TLV"
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Perf Monitoring Type (IANA)| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|L|J|Y|K|C| Reserved (set to all 0s) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub-TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Performance Monitoring sub-TLV
o D: Delay inferred/direct (0=INFERRED, 1=DIRECT)
o L: Loss inferred/direct (0=INFERRED, 1=DIRECT)
o J: Delay variation/jitter (1=ACTIVE, 0=NOT ACTIVE)
o Y: Dyadic (1=ACTIVE, 0=NOT ACTIVE)
o K: Loopback (1=ACTIVE, 0=NOT ACTIVE)
o C: Combined (1=ACTIVE, 0=NOT ACTIVE)
5.2.2.1. MPLS-TP PW PM Loss TLV
The "MPLS-TP PW PM Loss sub-TLV" depicted below is carried as a sub-
TLV of the "Performance Monitoring sub-TLV".
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PM Loss Type (1) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OTF |T|B| RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Test Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MPLS-TP PW PM Loss sub-TLV
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Type: indicates a new type, the "MPLS-TP PW PM Loss sub-TLV" (IANA to
define, suggested value 1).
Length: indicates the length of the parameters in octets.
OTF: Origin Timestamp Format of the Origin Timestamp field described
in [RFC6374]. By default it is set to IEEE 1588 version 1.
Configuration Flags, please refer to [RFC6374] for further details:
o T: Traffic-class-specific measurement indicator. Set to 1 when
the measurement operation is scoped to packets of a particular
traffic class (DSCP value), and 0 otherwise. When set to 1, the
DS field of the message indicates the measured traffic class. By
default it is set to 1.
o B: Octet (byte) count. When set to 1, indicates that the Counter
1-4 fields represent octet counts. When set to 0, indicates that
the Counter 1-4 fields represent packet counts. By default it is
set to 0.
Measurement Interval: the time interval (in microseconds) at which LM
query messages MUST be sent on both directions. If the T-PE
receiving the Mapping message can not support such value, it can
reply back with a higher interval. By default it is set to (TBD).
Test Interval: test messages interval as described in [RFC6374]. By
default it is set to (TBD).
Loss Threshold: the threshold value of lost packets over which
protections MUST be triggered. By default it is set to (TBD).
5.2.2.2. MPLS-TP PW PM Delay TLV
The "MPLS-TP PW PM Delay sub-TLV" depicted below is carried as a sub-
TLV of the "MPLS-TP PW OAM Configuration TLV"
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PM Delay Type (2) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OTF |T|B| RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Test Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Delay Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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MPLS-TP PW PM Delay sub-TLV
Type: indicates a new type, the "MPLS-TP PW PM Delay sub-TLV" (IANA
to define, suggested value 2).
Length: indicates the length of the parameters in octets.
OTF: Origin Timestamp Format of the Origin Timestamp field described
in [RFC6374]. By default it is set to IEEE 1588 version 1.
Configuration Flags, please refer to [RFC6374] for further details:
o T: Traffic-class-specific measurement indicator. Set to 1 when
the measurement operation is scoped to packets of a particular
traffic class (DSCP value), and 0 otherwise. When set to 1, the
DS field of the message indicates the measured traffic class. By
default it is set to 1.
o B: Octet (byte) count. When set to 1, indicates that the Counter
1-4 fields represent octet counts. When set to 0, indicates that
the Counter 1-4 fields represent packet counts. By default it is
set to 0.
Measurement Interval: the time interval (in microseconds) at which LM
query messages MUST be sent on both directions. If the T-PE
receiving the Mapping message can not support such value, it can
reply back with a higher interval. By default it is set to (TBD).
Test Interval: test messages interval as described in [RFC6374]. By
default it is set to (TBD).
Delay Threshold: the threshold value of packet delay time over which
protections MUST be triggered. By default it is set to (TBD).
5.2.3. MPLS-TP PW FMS TLV
The "MPLS-TP PW FMS sub-TLV" depicted below is carried as a sub-TLV
of the "MPLS-TP PW OAM Configuration TLV".
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Fault mgmt Type (4) (IANA) | Length (8) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|D|L| Reserved (set to all 0s) |E| PHB |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Refresh Timer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MPLS-TP PW FMS sub-TLV
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Type: indicates a new type, the "MPLS-TP PW FMS sub-TLV" (IANA to
define, suggested value 4).
Length: indicates the length of the parameters in octets (8).
Signal Flags: are used to enable the following signals:
o A: Alarm Indication Signal (AIS) as described in [RFC6428]
o D: Link Down Indication (LDI) as described in [RFC6428]
o L: Locked Report (LKR) as described in [RFC6428]
o Remaining bits: Reserved for future specification and set to 0.
Configuration Flags:
o E: used to enable/disable explicitly clearing faults
o PHB: identifies the per-hop behavior of packets with fault
management information
Refresh Timer: indicates the refresh timer (in microseconds) of fault
indication messages. If the T-PE receiving the Path message can not
support such value, it can reply back with a higher interval.
6. IANA Considerations
This document specifies the following new LDP TLV types:
o MPLS-TP PW OAM Administration TLV;
o MPLS-TP PW OAM Configuration TLV;
Sub-TLV types to be carried in the "MPLS-TP PW OAM Configuration
TLV":
o BFD Configuration sub-TLV;
o Performance Monitoring sub-TLV
o MPLS-TP PW FMS sub-TLV;
Sub-TLV types to be carried in the "BFD Configuration sub-TLV":
o Local Discriminator sub-TLV;
o Negotiation Timer Parameters sub-TLV.
o BFD Authentication sub-TLV
Sub-TLV types to be carried in the "Performance Monitoring sub-TLV":
o MPLS-TP PW PM Loss sub-TLV;
o MPLS-TP PW PM Loss sub-TLV.
6.1. OAM Configuration Errors
This document defines several new LDP status codes, IANA already
maintains the registry "STATUS CODE NAME SPACE" defined by [RFC5036].
The following values are required to be assigned:
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Range/Value E Description
0x0000003C 0 "MIP Configuration Failure"
0x0000003D 0 "Rejected MPLS-TP PW OAM Configuration TLV"
0x0000003E 0 "Wrong MPLS-TP PW OAM Configuration TLV"
0x0000003F 0 "Unsupported OAM Version"
0x0000004A 0 "Unsupported BFD TX Echo rate interval"
7. Security Considerations
Security considerations relating to LDP are described in section 5 of
[RFC5036] and section 11 of [RFC5561]. Security considerations
relating to use of LDP in setting up PWs is described in section 8 of
[RFC4447].
This document defines new TLV/sub-TLV types, and OAM configuration
procedures intended for use with MPLS-TP, which do not raise any
additional security issues.
8. Acknowledgement
The authors would like to thank Andew Malis, Greg Mirsky, Luca
Martini, Matthew Bocci, Thomas Nadeau for their valuable comments and
discussions, especially would like to thank Eric Gray for his review
of this document.
9. References
9.1. Normative references
[I-D.ietf-mpls-lsp-ping-mpls-tp-oam-conf]
Bellagamba, E., Andersson, L., Skoldstrom, P., Ward, D.,
and J. Drake, "Configuration of Pro-Active Operations,
Administration, and Maintenance (OAM) Functions for MPLS-
based Transport Networks using LSP Ping",
draft-ietf-mpls-lsp-ping-mpls-tp-oam-conf-04 (work in
progress), April 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4447] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G.
Heron, "Pseudowire Setup and Maintenance Using the Label
Distribution Protocol (LDP)", RFC 4447, April 2006.
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[RFC5860] Vigoureux, M., Ward, D., and M. Betts, "Requirements for
Operations, Administration, and Maintenance (OAM) in MPLS
Transport Networks", RFC 5860, May 2010.
[RFC6073] Martini, L., Metz, C., Nadeau, T., Bocci, M., and M.
Aissaoui, "Segmented Pseudowire", RFC 6073, January 2011.
9.2. Informative References
[RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-
Edge (PWE3) Architecture", RFC 3985, March 2005.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL.
Le Roux, "LDP Capabilities", RFC 5561, July 2009.
[RFC5654] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N.,
and S. Ueno, "Requirements of an MPLS Transport Profile",
RFC 5654, September 2009.
[RFC5659] Bocci, M. and S. Bryant, "An Architecture for Multi-
Segment Pseudowire Emulation Edge-to-Edge", RFC 5659,
October 2009.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, June 2010.
[RFC6371] Busi, I. and D. Allan, "Operations, Administration, and
Maintenance Framework for MPLS-Based Transport Networks",
RFC 6371, September 2011.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374, September 2011.
[RFC6375] Frost, D. and S. Bryant, "A Packet Loss and Delay
Measurement Profile for MPLS-Based Transport Networks",
RFC 6375, September 2011.
[RFC6428] Allan, D., Swallow Ed. , G., and J. Drake Ed. , "Proactive
Connectivity Verification, Continuity Check, and Remote
Defect Indication for the MPLS Transport Profile",
RFC 6428, November 2011.
[RFC6669] Sprecher, N. and L. Fang, "An Overview of the Operations,
Administration, and Maintenance (OAM) Toolset for MPLS-
Based Transport Networks", RFC 6669, July 2012.
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Authors' Addresses
Fei Zhang (editor)
ZTE Corporation
Email: zhang.fei3@zte.com.cn
Bo Wu (editor)
ZTE Corporation
Email: wu.bo@zte.com.cn
Elisa Bellagamba (editor)
Ericsson
Farogatan 6
Kista, 164 40
Sweden
Phone: +46 761440785
Email: elisa.bellagamba@ericsson.com
Attila Takacs
Ericsson
Laborc u. 1.
Budapest, 1037
Hungary
Email: attila.takacs@ericsson.com
Xuehui Dai
ZTE Corporation
Email: dai.xuehui@zte.com.cn
Min Xiao
ZTE Corporation
Email: xiao.min2@zte.com.cn
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