draft-ietf-mpls-tp-cc-cv-rdi-02.txt   draft-ietf-mpls-tp-cc-cv-rdi-03.txt 
MPLS Working Group Dave Allan, Ed. MPLS Working Group Dave Allan, Ed.
Internet Draft Ericsson Internet Draft Ericsson
Intended status: Standards Track Intended status: Standards Track
Expires: April 2011 George Swallow Ed. Expires: August 2011 George Swallow Ed.
Cisco Systems, Inc Cisco Systems, Inc
John Drake Ed. John Drake Ed.
Juniper Juniper
October 22, 2010 February 2, 2011
Proactive Connectivity Verification, Continuity Check and Remote Proactive Connectivity Verification, Continuity Check and Remote
Defect indication for MPLS Transport Profile Defect indication for MPLS Transport Profile
draft-ietf-mpls-tp-cc-cv-rdi-02 draft-ietf-mpls-tp-cc-cv-rdi-03
Abstract Abstract
Continuity Check (CC), Proactive Connectivity Verification (CV) and Continuity Check (CC), Proactive Connectivity Verification (CV) and
Remote Defect Indication (RDI) functionalities are required for MPLS- Remote Defect Indication (RDI) functionalities are required for MPLS-
TP OAM. TP OAM.
Continuity Check monitors the integrity of the continuity of the LSP Continuity Check monitors the integrity of the continuity of the LSP
for any loss of continuity defect. Connectivity verification monitors for any loss of continuity defect. Connectivity verification monitors
the integrity of the routing of the LSP between sink and source for the integrity of the routing of the LSP between sink and source for
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documents at any time. It is inappropriate to use Internet- documents at any time. It is inappropriate to use Internet-
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in progress". in progress".
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on November 28, 2010. This Internet-Draft will expire on August 2nd 2011.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction...................................................3 1. Introduction...................................................3
1.1. Authors......................................................4 1.1. Authors......................................................4
2. Conventions used in this document..............................4 2. Conventions used in this document..............................4
2.1. Terminology..................................................4 2.1. Terminology..................................................4
2.2. Issues for discussion........................................5
3. MPLS CC, proactive CV and RDI Mechanism using BFD..............5 3. MPLS CC, proactive CV and RDI Mechanism using BFD..............5
3.1. ACH code points for CC and proactive CV......................6 3.1. ACH code points for CC and proactive CV......................6
3.2. MPLS BFD CC Message format...................................6 3.2. MPLS BFD CC Message format...................................6
3.3. MPLS BFD proactive CV Message format.........................7 3.3. MPLS BFD proactive CV Message format.........................7
3.4. BFD Session in MPLS-TP terminology...........................7 3.3.1. ICC-based MEP-ID...........................................8
3.5. BFD Profile for MPLS-TP......................................8 3.3.2. LSP MEP-ID.................................................8
3.5.1. Session initiation.........................................9 3.3.3. PW Endpoint MEP-ID.........................................8
3.5.2. Defect entry criteria......................................9 3.4. BFD Session in MPLS-TP terminology...........................8
3.5.3. Defect entry consequent action............................10 3.5. BFD Profile for MPLS-TP......................................9
3.5.4. Defect exit criteria......................................11 3.5.1. Session initiation........................................10
3.5.5. State machines............................................11 3.5.2. Defect entry criteria.....................................10
3.5.6. Configuration of MPLS-TP BFD sessions.....................14 3.5.3. Defect entry consequent action............................11
3.5.7. Discriminator values......................................14 3.5.4. Defect exit criteria......................................12
4. Acknowledgments...............................................15 3.5.5. State machines............................................12
5. IANA Considerations...........................................15 3.5.6. Configuration of MPLS-TP BFD sessions.....................15
6. Security Considerations.......................................15 3.5.7. Discriminator values......................................15
7. References....................................................15 4. Acknowledgments...............................................16
7.1. Normative References........................................15 5. IANA Considerations...........................................16
7.2. Informative References......................................16 6. Security Considerations.......................................16
7. References....................................................16
7.1. Normative References........................................16
7.2. Informative References......................................17
1. Introduction 1. Introduction
In traditional transport networks, circuits are provisioned on two or In traditional transport networks, circuits are provisioned on two or
more switches. Service Providers (SP) need OAM tools to detect mis- more switches. Service Providers (SP) need OAM tools to detect mis-
connectivity and loss of continuity of transport circuits. Both PWs connectivity and loss of continuity of transport circuits. Both PWs
and MPLS-TP LSPs [7] emulating traditional transport circuits need to and MPLS-TP LSPs [10] emulating traditional transport circuits need
provide the same CC and proactive CV capabilities as required in to provide the same CC and proactive CV capabilities as required in
draft-ietf-mpls-tp-oam-requirements[3]. This document describes the RFC 5860[3]. This document describes the use of BFD for CC, proactive
use of BFD for CC, proactive CV, and RDI of a PW, LSP or SPME between CV, and RDI of a PW, LSP or SPME between two Maintenance Entity Group
two Maintenance Entity Group End Points (MEPs). End Points (MEPs).
As described in [9], Continuity Check (CC) and Proactive Connectivity As described in [11], Continuity Check (CC) and Proactive
Verification (CV) functions are used to detect loss of continuity Connectivity Verification (CV) functions are used to detect loss of
(LOC), and unintended connectivity between two MEPs (e.g. mismerging continuity (LOC), and unintended connectivity between two MEPs (e.g.
or misconnectivity or unexpected MEP). mismerging or misconnectivity or unexpected MEP).
The Remote Defect Indication (RDI) is an indicator that is The Remote Defect Indication (RDI) is an indicator that is
transmitted by a MEP to communicate to its peer MEP that a signal transmitted by a MEP to communicate to its peer MEP that a signal
fail condition exists. RDI is only used for bidirectional LSPs and is fail condition exists. RDI is only used for bidirectional LSPs and is
associated with proactive CC & CV packet generation. associated with proactive CC & CV packet generation.
This document specifies the BFD extension and behavior to satisfy the This document specifies the BFD extension and behavior to satisfy the
CC, proactive CV monitoring and the RDI functional requirements for CC, proactive CV monitoring and the RDI functional requirements for
both co-routed and associated bi-directional LSPs. Supported both co-routed and associated bi-directional LSPs. Supported
encapsulations include GAL/G-ACh, VCCV and UDP/IP. Procedures for encapsulations include GAL/G-ACh, VCCV and UDP/IP. Procedures for
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RDI: Remote Defect Indication. RDI: Remote Defect Indication.
SPME: Sub-Path Maintenance Entity SPME: Sub-Path Maintenance Entity
TTL: Time To Live TTL: Time To Live
TLV: Type Length Value TLV: Type Length Value
VCCV: Virtual Circuit Connectivity Verification VCCV: Virtual Circuit Connectivity Verification
2.2. Issues for discussion
1) Requirement for additional BFD diagnostic codes?
1. When periodicity of CV cannot be supported
3. MPLS CC, proactive CV and RDI Mechanism using BFD 3. MPLS CC, proactive CV and RDI Mechanism using BFD
This document proposes distinct encapsulations and code points for This document proposes distinct encapsulations and code points for
ACh encapsulated BFD depending on whether the mode of operation is CC ACh encapsulated BFD depending on whether the mode of operation is CC
or CV: or CV:
o CC mode: defines a new code point in the Associated Channel Header o CC mode: defines a new code point in the Associated Channel Header
(ACH) described in [2].In this mode Continuity Check and RDI (ACH) described in RFC 5586[2].In this mode Continuity Check and
functionalities are supported. RDI functionalities are supported.
o CV mode: defines a new code point in the Associated Channel Header o CV mode: defines a new code point in the Associated Channel Header
(ACH) described in [2]. The ACH with "MPLS Proactive CV" code (ACH) described in RFC 5586[2]. The ACH with "MPLS Proactive CV"
point indicates that the message is an MPLS BFD proactive CV and code point indicates that the message is an MPLS BFD proactive CV
CC message and CC, CV and RDI functionalities are supported. and CC message and CC, CV and RDI functionalities are supported.
RDI: is communicated via the BFD diagnostic field in BFD CC and CV RDI: is communicated via the BFD diagnostic field in BFD CC and CV
messages. It is not a distinct PDU. A sink MEP will encode a messages. It is not a distinct PDU. A sink MEP will encode a
diagnostic code of "1- Control detection time expired" when the diagnostic code of "1- Control detection time expired" when the
interval times detect multipler have been exceeded, and with "3 - interval times detect multipler have been exceeded, and with "3 -
neighbor signaled session down" as a consequence of the sink MEP neighbor signaled session down" as a consequence of the sink MEP
receiving AIS with LDI set. A sink MEP that has started sending diag receiving AIS with LDI set. A sink MEP that has started sending diag
code 3 will NOT change it to 1 when the detection timer expires. code 3 will NOT change it to 1 when the detection timer expires.
In accordance with RFC 5586, when these packets are encapsulated in In accordance with RFC 5586[2], when these packets are encapsulated
an IP header the fields in the IP header are set as defined in RFC in an IP header, the fields in the IP header are set as defined in
5884. It should also be noted that existing ACh code points and RFC 5884[8]. Further existing ACh code points and mechanisms for BFD
mechanisms for negotiating the control channel and connectivity VCCV are specified in RFC5885[7]. These MAY be applied to
verification (i.e. OAM functions) between PEs are specified for Pseudowires by configuration. Also by configuration, the BFD PW-ACH-
VCCV[6]. encapsulated for PW fault detection only encapsulation can be applied
to bi-directional LSPs by employing the GAL to indicate the presence
of the ACh.
A further artifact of IP encapsulation is that CV mis-connectivity
defect detection can be performed by inferring MEP_ID on the basis of
the combination of the source IP address and "my discriminator"
fields.
3.1. ACH code points for CC and proactive CV 3.1. ACH code points for CC and proactive CV
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 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 0 1|Version| Flags |0xHH BFD CC/CV Code Point | |0 0 0 1|Version| Flags |0xHH BFD CC/CV Code Point |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: ACH Indication of MPLS-TP Connectivity Verification Figure 1: ACH Indication of MPLS-TP Connectivity Verification
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The version and the flags are set to 0 as specified in [2]. The version and the flags are set to 0 as specified in [2].
The code point is either The code point is either
- BFD CC code point = 0xHH. [HH to be assigned by IANA from the PW - BFD CC code point = 0xHH. [HH to be assigned by IANA from the PW
Associated Channel Type registry.] or, Associated Channel Type registry.] or,
- BFD proactive CV code point = 0xHH. [HH to be assigned by IANA from - BFD proactive CV code point = 0xHH. [HH to be assigned by IANA from
the PW Associated Channel Type registry.] the PW Associated Channel Type registry.]
Both CC and CV modes apply to PWs, MPLS LSPs (including tandem Both CC and CV modes apply to PWs, MPLS LSPs (including SPMEs), and
connection monitoring), and Sections. Sections.
CC and CV operation can be simultaneously employed on an ME within a CC and CV operation can be simultaneously employed on an ME within a
single BFD session. The expected usage is that normal operation is to single BFD session. The expected usage is that normal operation is to
send CC BFD PDUs with every nth BFD PDU augmented with a source MEP send CC BFD PDUs with every nth BFD PDU augmented with a source MEP-
ID and identified as requiring additional processing by the different ID and identified as requiring additional processing by the different
ACh channel type. ACh channel type. When CC and CV are interleaved, the minimum
insertion interval for CV PDUs is one per second.
3.2. MPLS BFD CC Message format 3.2. MPLS BFD CC Message format
The format of an MPLS CC Message is shown below. The format of an MPLS CC Message is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 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 0 1|Version| Flags | 0xHH BFD CC Code point | |0 0 0 1|Version| Flags | 0xHH BFD CC Code point |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ Unique MEP-ID of source of the BFD packet ~ ~ Unique MEP-ID of source of the BFD packet ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: MPLS CV Message Figure 3: MPLS CV Message
As shown in Figure 3, BFD Control packet as defined in [4] is As shown in Figure 3, BFD Control packet as defined in [4] is
transmitted as MPLS labeled packets along with the ACH. Appended to transmitted as MPLS labeled packets along with the ACH. Appended to
the BFD control packet is a MEP Source ID TLV. The length in the BFD the BFD control packet is a MEP Source ID TLV.
control packet is as per [4]. There are 4 possible Source MEP TLVs
(corresponding to the MEP IDs defined in [8] [type fields to be
assigned by IANA]. The type fields are:
X1 - ICC encoded MEP ID A MEP Source ID TLV is encoded as a 2 octet field that specifies a
Type, followed by a 2 octet Length Field, followed by a variable
length Value field.
X2 - LSP-MEP_ID The length in the BFD control packet is as per [4]. There are 3
Source MEP TLVs (corresponding to the MEP-IDs defined in Error!
Reference source not found. [type fields to be assigned by IANA]. The
type fields are:
X3 - PW MEP ID X1 - ICC encoded MEP-ID
X4 - PW Segment endpoint ID X2 - LSP MEP-ID
X3 - PW MEP-ID
When GAL label is used, the TTL field of the GAL MUST be set to at When GAL label is used, the TTL field of the GAL MUST be set to at
least 1, and the GAL will be the end of stack label (S=1). least 1, and the GAL will be the end of stack label (S=1).
A node MUST NOT change the value in the MEP Source ID TLV.
When digest based authentication is used, the Source ID TLV MUST NOT
be included in the digest
3.3.1. ICC-based MEP-ID
As defined in [9], the ICC-based MEP_ID consists of the MEG_ID, a
string of up to 13 characters (A-Z and 0-9), followed by the MEP
Index, an unsigned 16 bit integer that MUST be unique within the
context of the MEG_ID.
3.3.2. LSP MEP-ID
As defined in [9], the MPLS_TP LSP MEP-ID consists of the Node
Identifier, a thirty two bit identifier that MUST be unique within
the context of an operator's network, followed by the Tunnel_Num, an
unsigned sixteen bit integer that MUST be unique within the context
of the Node Identifier, and the LSP_NUM, an unsigned sixteen bit
integer that MUST be unique with the context of the Tunnel Num.
3.3.3. PW Endpoint MEP-ID
As defined in [9], the PW Endpoint MEP-ID consists of the Node
Identifier, a thirty two bit identifier that MUST be unique within
the context of an operator's network, followed by the AC_ID, a thirty
two bit identifier that MUST be unique within the context of the Node
Identifier.
In situations where global uniqueness is required, the Node
Identifier is preceded by the Global ID, a thirty two bit identifier
that contains the two-octet (right hand justified and preceded by
sixteen bits of zero) or four-octet value of the operator's
Autonomous System Number (ASN).
3.4. BFD Session in MPLS-TP terminology 3.4. BFD Session in MPLS-TP terminology
A BFD session corresponds to a CC or a proactive CV OAM instance in A BFD session corresponds to a CC or a proactive CV OAM instance in
MPLS-TP terminology. MPLS-TP terminology.
A BFD session is enabled when the CC or proactive CV functionality is A BFD session is enabled when the CC or proactive CV functionality is
enabled on a configured Maintenance Entity (ME).. enabled on a configured Maintenance Entity (ME)..
On a Sink MEP, a BFD session can be in DOWN, INIT or UP state as On a Sink MEP, a BFD session can be in DOWN, INIT or UP state as
detailed in [4]. detailed in [4].
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A new BFD session is initiated when the operator enables or re- A new BFD session is initiated when the operator enables or re-
enables the CC or CV functionality on the same ME. enables the CC or CV functionality on the same ME.
3.5. BFD Profile for MPLS-TP 3.5. BFD Profile for MPLS-TP
BFD MUST operate in asynchronous mode. In this mode, the BFD Control BFD MUST operate in asynchronous mode. In this mode, the BFD Control
packets are periodically sent at configurable time rate. This rate is packets are periodically sent at configurable time rate. This rate is
typically a fixed value for the lifetime of the session. In the rare typically a fixed value for the lifetime of the session. In the rare
circumstance where an operator has a reason to change session circumstance where an operator has a reason to change session
parameters, the session must be moved to the ADMIN DOWN state. parameters, the session MUST be moved to the ADMIN DOWN state.
Poll/final discipline can only used for VCCV and UDP/IP encapsulated Poll/final discipline can only used for VCCV and UDP/IP encapsulated
BFD. BFD.
The transport profile is designed to operate independent of the
control plane; hence the C bit SHOULD be set.
This document specifies bi-directional BFD for p2p transport LSPs, This document specifies bi-directional BFD for p2p transport LSPs,
hence the M bit MUST be clear. hence the M bit MUST be clear.
There are two modes of operation for bi-directional LSPs. One in There are two modes of operation for bi-directional LSPs. One in
which the session state of both directions of the LSP is coordinated which the session state of both directions of the LSP is coordinated
and one constructed from BFD sessions in such a way that the two and one constructed from BFD sessions in such a way that the two
directions operate independently. A single bi-directional BFD session directions operate independently. A single bi-directional BFD session
is used for coordinated operation. Two independent BFD sessions are is used for coordinated operation. Two independent BFD sessions are
used for independent operation. used for independent operation.
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machine; these are the Link Down Indication [5] and the Lock machine; these are the Link Down Indication [5] and the Lock
Instruct/Lock Report transactions; Lock Report interaction being Instruct/Lock Report transactions; Lock Report interaction being
optional. optional.
3.5.1. Session initiation 3.5.1. Session initiation
In all scenarios a BFD session starts with both ends in the DOWN In all scenarios a BFD session starts with both ends in the DOWN
state. DOWN state messages exchanged include the desired Tx and Rx state. DOWN state messages exchanged include the desired Tx and Rx
rates for the session. If a node cannot support the Min Tx rate rates for the session. If a node cannot support the Min Tx rate
desired by a peer MEP it does not transition from down to the INIT desired by a peer MEP it does not transition from down to the INIT
state and sends a diagnostic code (TBD) indicating that the requested state and sends a diagnostic code of configuration error (to be
Tx rate cannot be supported. assigned by IANA) indicating that the requested Tx rate cannot be
supported.
Otherwise once a transition from DOWN to INIT has occurred, the Otherwise once a transition from DOWN to INIT has occurred, the
session progresses as per [4]. In both the DOWN and INIT states session progresses as per [4]. In both the DOWN and INIT states
messages are transmitted at a rate of one per second and the defect messages are transmitted at a rate of one per second and the defect
detection interval is fixed at 3.5 seconds. On transition to the UP detection interval is fixed at 3.5 seconds. On transition to the UP
state message periodicity changes to the negotiated rate and the state, message periodicity changes to the negotiated and/or
detect interval switches to detect multiplier times the session configured rate and the detect interval switches to detect multiplier
peer's Tx Rate. times the session peer's Tx Rate.
3.5.2. Defect entry criteria 3.5.2. Defect entry criteria
There are further defect criteria beyond those that are defined in There are further defect criteria beyond those that are defined in
[4] to consider given the possibility of mis-connectivity and mis- [4] to consider given the possibility of mis-connectivity and mis-
configuration defects. The result is the criteria for a LSP direction configuration defects. The result is the criteria for a LSP direction
to transition from the defect free state to a defect state is a to transition from the defect free state to a defect state is a
superset of that in the BFD base specification [4]. superset of that in the BFD base specification [4].
The following conditions cause a MEP to enter the defect state for CC The following conditions cause a MEP to enter the defect state for CC
or CV: or CV:
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3.5.2. Defect entry criteria 3.5.2. Defect entry criteria
There are further defect criteria beyond those that are defined in There are further defect criteria beyond those that are defined in
[4] to consider given the possibility of mis-connectivity and mis- [4] to consider given the possibility of mis-connectivity and mis-
configuration defects. The result is the criteria for a LSP direction configuration defects. The result is the criteria for a LSP direction
to transition from the defect free state to a defect state is a to transition from the defect free state to a defect state is a
superset of that in the BFD base specification [4]. superset of that in the BFD base specification [4].
The following conditions cause a MEP to enter the defect state for CC The following conditions cause a MEP to enter the defect state for CC
or CV: or CV:
1. BFD session times out (Loss of Continuity defect). 1. BFD session times out (Loss of Continuity defect).
2. Receipt of a link down indication. 2. Receipt of a link down indication.
3. Receipt of an unexpected M bit (Session Mis-configuration 3. Receipt of an unexpected M bit (Session Mis-configuration
defect). defect).
And the following will cause the MEP to enter the defect state for CV And the following will cause the MEP to enter the defect state for CV
operation operation
1. BFD control packets are received with an unexpected 1. BFD control packets are received with an unexpected
encapsulation (mis-connectivity defect), these include: encapsulation (mis-connectivity defect), these include:
- a PW receiving a packet with a GAL - a PW receiving a packet with a GAL
- an LSP receiving an IP header instead of a GAL - receiving an IP encoded CC or CV packet on a LSP configured
to use GAL/GaCH, or vice versa
(note there are other possibilities that can also alias as an (note there are other possibilities that can also alias as an
OAM packet) OAM packet)
2. Receipt of an unexpected globally unique Source MEP identifier 2. Receipt of an unexpected globally unique Source MEP identifier
(Mis-connectivity defect). (Mis-connectivity defect).
3. Receipt of an unexpected session discriminator in the your 3. Receipt of an unexpected session discriminator in the your
discriminator field (mis-connectivity defect). discriminator field (mis-connectivity defect).
4. Receipt of an expected session discriminator with an unexpected 4. Receipt of an expected session discriminator with an unexpected
label (mis-connectivity defect). label (mis-connectivity defect).
5. IF BFD authentication is used, receipt of a message with
incorrect authentication information (password, MD5 digest, or
SHA1 hash).
The effective defect hierarchy (order of checking) is The effective defect hierarchy (order of checking) is
1. Receiving nothing. 1. Receiving nothing.
2. Receiving link down indication. 2. Receiving link down indication.
3. Receiving from an incorrect source (determined by whatever 3. Receiving from an incorrect source (determined by whatever
means). means).
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5. Receiving control packets in all discernable ways correct. 5. Receiving control packets in all discernable ways correct.
3.5.3. Defect entry consequent action 3.5.3. Defect entry consequent action
Upon defect entry a sink MEP will assert signal fail into any client Upon defect entry a sink MEP will assert signal fail into any client
(sub-)layers. It will also communicate session DOWN to its session (sub-)layers. It will also communicate session DOWN to its session
peer. peer.
The blocking of traffic as consequent action MUST be driven only by a The blocking of traffic as consequent action MUST be driven only by a
defect's consequent action as specified in draft-ietf-mpls-tp-oam- defect's consequent action as specified in draft-ietf-mpls-tp-oam-
framework [9] section 5.1.1.2. framework [11] section 5.1.1.2.
When the defect is mis-branching, the LSP termination will silently When the defect is mis-branching, the LSP termination will silently
discard all non-oam traffic received. discard all non-oam traffic received.
3.5.4. Defect exit criteria 3.5.4. Defect exit criteria
3.5.4.1. Exit from a Loss of continuity defect 3.5.4.1. Exit from a Loss of continuity defect
For a coordinated session, exit from a loss of connectivity defect is For a coordinated session, exit from a loss of connectivity defect is
as described in figure 4 which updates [4]. as described in figure 4 which updates [4].
For an independent session, exit from a loss of connectivity defect For an independent session, exit from a loss of connectivity defect
occurs upon receipt of a well formed control packet from the peer MEP occurs upon receipt of a well formed control packet from the peer MEP
as described in figures 5 and 6. as described in figures 5 and 6.
3.5.4.2. Exit from a session mis-configuration defect 3.5.4.2. Exit from a session mis-configuration defect
[editors: for a future version of the document] Exit from a misconfiguration defect occurs when two consecutive CC or
CV frames have been received with the expected M bit setting.
3.5.4.3. Exit from a mis-connectivity defect 3.5.4.3. Exit from a mis-connectivity defect
[Editors node: The shift to CC with interleaved CV suggests the CV Exit from a mis-connectivity defect state occurs when no CV messages
periodicity may not be known by a sink MEP, hence exit criteria from have been received with an incorrect source MEP-ID for a period of
a mis-connectivity defect may not be able to be established. We 3.5 seconds.
suggest two possible resolutions for this:
1. Exit criteria is manual intervention.
2. A minimum CV insertion rate (say 1/sec) be specified such that
the exit criteria be specified as no mis-connected CV PDUs be
received for a minimum of 3 times the minimum insertion rate]
3.5.5. State machines 3.5.5. State machines
The following state machines update [4]. They have been modified to The following state machines update [4]. They have been modified to
include AIS with LDI set and LKI as inputs to the state machine and include AIS with LDI set and LKI as specified in [5] as inputs to the
to clarify the behavior for independent mode. LKR is an optional state machine and to clarify the behavior for independent mode. LKR
input. is an optional input.
The coordinated session state machine has been augmented to indicate The coordinated session state machine has been augmented to indicate
AIS with LDI set and optionally LKR as inputs to the state machine. AIS with LDI set and optionally LKR as inputs to the state machine.
For a session that is in the UP state, receipt of AIS with LDI set or For a session that is in the UP state, receipt of AIS with LDI set or
optionally LKR will transition the session into the DOWN state. optionally LKR will transition the session into the DOWN state.
+--+ +--+
| | UP, ADMIN DOWN, TIMER, AIS-LDI, LKR | | UP, ADMIN DOWN, TIMER, AIS-LDI, LKR
| V | V
DOWN +------+ INIT DOWN +------+ INIT
skipping to change at page 14, line 30 skipping to change at page 15, line 30
+----| | | |----+ +----| | | |----+
DOWN| | INIT |--------------------->| UP | |INIT, UP DOWN| | INIT |--------------------->| UP | |INIT, UP
+--->| | INIT, UP | |<---+ +--->| | INIT, UP | |<---+
+------+ +------+ +------+ +------+
Figure 6: State machine for the sink MEP for independent session Figure 6: State machine for the sink MEP for independent session
operation operation
3.5.6. Configuration of MPLS-TP BFD sessions 3.5.6. Configuration of MPLS-TP BFD sessions
[Editors note, for a future revision of the document] Configuration of MPLS-TP BFD session paramters and coordination of
same between the source and sink MEPs is out of scope of this memo.
3.5.7. Discriminator values 3.5.7. Discriminator values
In the BFD control packet the discriminator values have either local In the BFD control packet the discriminator values have either local
to the sink MEP or no significance (when not known). to the sink MEP or no significance (when not known).
My Discriminator field MUST be set to a nonzero value (it can be a My Discriminator field MUST be set to a nonzero value (it can be a
fixed value), the transmitted your discriminator value MUST reflect fixed value), the transmitted your discriminator value MUST reflect
back the received value of My discriminator field or be set to 0 if back the received value of My discriminator field or be set to 0 if
that value is not known. that value is not known.
Although the BFD base specification permits an implementation to Per RFC5884 Section 7 [8], a node MUST NOT change the value of the
change the my discriminator field at arbitrary times, this is not "my discriminator" field for an established BFD session.
permitted for CV mode in order to avoid race conditions in mis-
connectivity defects.
4. Acknowledgments 4. Acknowledgments
To be added in a later version of this document Nitin Bahadur, Rahul Aggarwal, Dave Ward, Tom Nadeau, Nurit
Sprecher and Yaacov Weingarten also contributed to this
document.
5. IANA Considerations 5. IANA Considerations
To be added in a later version of this document This draft requires the allocation of two channel types from the
the IANA "PW Associated Channel Type" registry in RFC4446 [6].
6. Security Considerations Xx MPLS-TP CC message
The security considerations for the authentication TLV need further Xx+1 MPLS-TP CV message
study.
Base BFD foresees an optional authentication section (see [4] This draft requires the creations of a source MEP-ID TLV
section 6.7); that can be extended also to the tool proposed in registry with initial values of:
this document.
Authentication methods that require checksum calculation on the Xx - ICC encoded MEP-ID
outgoing packet must extend the checksum also on the ME
Identifier Section. This is possible but seems uncorrelated with Xx+1 - LSP MEP-ID
the solution proposed in this document: it could be better to
use the simple password authentication method. Xx+2 - PW MEP-ID
The source MEP-ID TLV will require standards action registration
procedures for additional values.
This memo requests a code point from the registry for BFD
diagnostic codes [4]:
Xx - configuration error
6. Security Considerations
Base BFD foresees an optional authentication section (see [4]
section 6.7); that can be applied to this application.
7. References 7. References
7.1. Normative References 7.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate [1] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[2] Bocci, M. et al., " MPLS Generic Associated Channel ", RFC [2] Bocci, M. et al., " MPLS Generic Associated Channel ", RFC
5586 , June 2009 5586 , June 2009
[3] Vigoureux, M., Betts, M. and D. Ward, "Requirements for [3] Vigoureux, M., Betts, M. and D. Ward, "Requirements for
Operations Administration and Maintenance in MPLS Operations Administration and Maintenance in MPLS
Transport Networks", RFC5860, May 2010 Transport Networks", RFC5860, May 2010
[4] Katz, D. and D. Ward, "Bidirectional Forwarding [4] Katz, D. and D. Ward, "Bidirectional Forwarding
Detection", RFC 5880, June 2010 Detection", RFC 5880, June 2010
[5] Swallow, G. et al., "MPLS Fault Management OAM", draft- [5] Swallow, G. et al., "MPLS Fault Management OAM", draft-
ietf-mpls-tp-fault-02 (work in progress), July 2010 ietf-mpls-tp-fault-03 (work in progress), October 2010
[6] Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit [6] Martini, L., " IANA Allocations for Pseudowire Edge to
Connectivity Verification (VCCV): A Control Channel for Edge Emulation (PWE3)", RFC 4446, April 2006
Pseudowires", RFC 5085, December 2007
7.2. Informative References [7] Nadeau, T. et al. "Bidirectional Forwarding Detection
(BFD) for the Pseudowire Virtual Circuit Connectivity
Verification (VCCV) ", IETF RFC 5885, June 2010
[7] Bocci, M., et al., "A Framework for MPLS in Transport [8] Aggarwal, R. et.al., "Bidirectional Forwarding Detection
Networks", RFC5921, July 2010 (BFD) for MPLS Label Switched Paths (LSPs)", RFC 5884,
June 2010
[8] Bocci, M. and G. Swallow, "MPLS-TP Identifiers", draft- [9] Bocci, M. and G. Swallow, "MPLS-TP Identifiers", draft-
swallow-mpls-tp-identifiers-02 (work in progress), July ietf-mpls-tp-identifiers-03 (work in progress), October
2010 2010
[9] Allan, D., and Busi, I. "MPLS-TP OAM Framework", draft- 7.2. Informative References
ietf-mpls-tp-oam-framework-09 (work in progress), October
[10] Bocci, M., et al., "A Framework for MPLS in Transport
Networks", RFC5921, July 2010
[11] Allan, D., and Busi, I. "MPLS-TP OAM Framework", draft-
ietf-mpls-tp-oam-framework-10 (work in progress), December
2010 2010
Authors' Addresses Authors' Addresses
Dave Allan Dave Allan
Ericsson Ericsson
Email: david.i.allan@ericsson.com Email: david.i.allan@ericsson.com
John Drake John Drake
Juniper Juniper
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