| CCAMP Working Group | E. Bellagamba, Ed. |
| Internet-Draft | L. Andersson, Ed. |
| Intended status: Standards Track | Ericsson |
| Expires: September 14, 2011 | P. Skoldstrom, Ed. |
| Acreo AB | |
| D. Ward | |
| Juniper | |
| A. Takacs | |
| Ericsson | |
| March 13, 2011 |
Configuration of pro-active MPLS-TP Operations, Administration, and Maintenance (OAM) Functions Using RSVP-TE
draft-ietf-ccamp-rsvp-te-mpls-tp-oam-ext-05
This specification describes the configuration of pro-active MPLS-TP Operations, Administration, and Maintenance (OAM) Functions for a given LSP using a set of TLVs that can be carried in the RSVP-TE protocol.
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This document describes the configuration of pro-active MPLS-TP Operations, Administration, and Maintenance (OAM) Functions for a given LSP using a common set of TLVs carried on RSVP-TE [RFC3209]. In particular it specifies the mechanisms necessary to establish MPLS-TP OAM entities monitoring an LSP and defines information elements and procedures to configure pro-active MPLS OAM functions. Initialization and control of on-demand MPLS OAM functions are expected to be carried out by directly accessing network nodes via a management interface; hence configuration and control of on-demand OAM functions are out-of-scope for this document.
Pro-active MPLS OAM is based on the Bidirectional Forwarding Detection (BFD) protocol [RFC5880]. Bidirectional Forwarding Detection (BFD), as described in [RFC5880], defines a protocol that provides low- overhead, short-duration detection of failures in the path between two forwarding engines, including the interfaces, data link(s), and to the extent possible the forwarding engines themselves. BFD can be used to track the liveliness and detect data plane failures of MPLS-TP point-to-point and might also be extended to p2mp connections.
MPLS Transport Profile (MPLS-TP) describes a profile of MPLS that enables operational models typical in transport networks, while providing additional OAM, survivability and other maintenance functions not currently supported by MPLS. [RFC5860] defines the requirements for the OAM functionality of MPLS-TP.
BFD has been chosen to be the basis of pro-active MPLS-TP OAM functions. MPLS-TP OAM extensions for transport applications, for which this document specifies the configuration, are specified in [BFD-CCCV], [MPLS-PM], and [MPLS-FMS].
This document is the result of a large team of authors and contributors. The following is a list of the co-authors:
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 RFC 2119 [RFC2119].
BFD is a simple hello protocol that in many respects is similar to the detection components of well-known routing protocols. A pair of systems transmits BFD packets periodically over each path between the two systems, and if a system stops receiving BFD packets for long enough, some component in that particular bidirectional path to the neighboring system is assumed to have failed. Systems may also negotiate to not send periodic BFD packets in order to reduce overhead.
A path is only declared to be operational when two-way communication has been established between systems, though this does not preclude the use of unidirectional links to support bidirectional paths (co-routed or bidirectional or associated bidirectional).
Each system estimates how quickly it can send and receive BFD packets in order to come to an agreement with its neighbor about how rapidly detection of failure will take place. These estimates can be modified in real time in order to adapt to unusual situations. This design also allows for fast systems on a shared medium with a slow system to be able to more rapidly detect failures between the fast systems while allowing the slow system to participate to the best of its ability. However, in some cases one may want to configure these timers manually, in those cases the TLVs defined in this document can be used.
The ability of each system to control the BFD packet transmission rate in both directions provides a mechanism for congestion control, particularly when BFD is used across multiple network hops.
As recommended in [BFD-CCCV], the BFD tool needs to be extended for the proactive CV functionality by the addition of an unique identifier in order to meet the requirements. The document in [BFD-CCCV] specifies the BFD extension and behavior to meet the requirements for MPLS-TP proactive Continuity Check and Connectivity Verification functionality and the RDI functionality as defined in [RFC5860].
[MPLS-TP-OAM-FWK] describes how MPLS OAM mechanisms are operated to meet transport requirements outlined in [RFC5860].
[BFD-CCCV] specifies two BFD operation modes: 1) "CC mode", which uses periodic BFD message exchanges with symmetric timer settings, supporting Continuity Check, 2) "CV/CC mode" which sends unique maintenance entity identifiers in the periodic BFD messages supporting Connectivity Verification as well as Continuity Check.
[MPLS-PM] specifies mechanisms for performance monitoring of LSPs, in particular it specifies loss and delay measurement OAM functions.
[MPLS-FMS] specifies fault management signals with which a server LSP can notify client LSPs about various fault conditions to suppress alarms or to be used as triggers for actions in the client LSPs. The following signals are defined: Alarm Indication Signal (AIS), Link Down Indication (LDI) and Locked Report (LKR). To indicate client faults associated with the attachment circuits Client Signal Failure Indication (CSF) can be used. CSF is described in [MPLS-TP-OAM-FWK] and in the context of this document is for further study.
[MPLS-TP-OAM-FWK] describes the mapping of fault conditions to consequent actions. Some of these mappings may be configured by the operator, depending on the application of the LSP. The following defects are identified: Loss Of Continuity (LOC), Misconnectivity, MEP Misconfiguration and Period Misconfiguration. Out of these defect conditions, the following consequent actions may be configurable: 1) whether or not the LOC defect should result in blocking the outgoing data traffic; 2) whether or not the "Period Misconfiguration defect" should result a signal fail condition.
RSVP-TE, or in alternative LSP Ping [LSP-PING CONF], can be used to simply establish (i.e., bootstrap) a BFD session or it can selectively enable and configure all pro-active MPLS OAM functions. For this specification, BFD MUST be run in asynchronous mode and both sides should be in active mode.
In the simplest scenario RSVP-TE, or in alternative LSP Ping [LSP-PING CONF], is used only to bootstrap the BFD session. In this case the initiating node includes an "OAM Configuration TLV" in the message it sends to the receiving node at the other end of the LSP. The OAM Type in the "OAM Configuration TLV" is set to "MPLS OAM", the CC OAM Function flag is set, and a "BFD Configuration sub-TLV" is included. The sub-TLV carries a "Local Discriminator sub-TLV" with the discriminator value selected by the initiating node for the BFD session associated with the LSP. The N flag in the "BFD Configuration sub-TLV" MUST be set to enable timer negotiation/re-negotiation via BFD Control Messages.
The receiving node MUST use the Local Discriminator value it receives to identify the remote end of the BFD session. The receiving node must send a message to the initiating node that includes an "OAM Configuration TLV" containing the same values as it received, except for the "Local Discriminator sub-TLV", which contains the local discriminator value selected by the receiving node for the BFD session.
Timer negotiation is performed in subsequent BFD control messages. This operation is similar to LSP Ping based bootstrapping described in [RFC5884].
If timer negotiation is to be done using the TLVs defined in this document rather than with BFD Control packets, the N flag MUST be cleared and a "Timer Negotiation Parameters sub-TLV" MUST be present in the "BFD Configuration sub-TLV". In this case, there are two configuration options, symmetric and asymmetric. If symmetric configuration is used, the S flag in "BFD Configuration sub-TLV" MUST be set. If the flag is cleared, the configuration is completed asymmetrically in the two directions. Section 3.3.2 includes a detailed explanation of such configuration.
In the case of the "CV/CC mode" OAM [BFD-CCCV], the "CV" flag MUST be set in addition to the CC flag in the "OAM Configuration TLV". The information required to support this functionality is defined in [MPLS-TP-IDENTIF]. If RSVP-TE is used, this information is found respectively in the SESSION and SENDER_TEMPLATE object with no need of additional sub-TLVs as described in section 3.2.
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 thus 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.
Additional OAM functions may be configured by setting the appropriate flags in the "OAM Functions TLV", these include Performance Measurements (packet loss and packet delay) and Fault Management Signal handling.
By setting the PM Loss flag in the "OAM Functions TLV" and including the "MPLS OAM 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 "OAM Functions TLV" and including the "MPLS OAM PM Loss sub-TLV" one can configure the measurement interval and the delay threshold values for triggering protection.
To configure Fault Monitoring Signals and their refresh time the FMS flag in the "OAM Functions TLV" MUST be set and the "MPLS OAM FMS sub-TLV" included.
The "OAM Configuration TLV" is depicted in the following figure. It specifies the OAM functions that are to be used for the subject LSP and it is defined in [OAM-CONF-FWK]. The "OAM Configuration TLV" is carried in the LSP_ATTRIBUTES object in Path and Resv messages.
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) (IANA) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OAM Type | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ sub-TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates the "OAM Configuration TLV" (2) (IANA to assign).
OAM Type: one octet that specifies the technology specific OAM Type. If the requested OAM Type is not supported, an error must be generated: "OAM Problem/Unsupported OAM Type".
This document defines a new OAM Type: "MPLS OAM" (suggested value 2, IANA to assign) from the "RSVP-TE OAM Configuration Registry". The "MPLS OAM" type is set to request the establishment of OAM functions for MPLS-TP LSPs. The specific OAM functions are specified in the "Function Flags" sub-TLV as depicted in [OAM-CONF-FWK].
The receiving edge LSR when the MPLS-TP OAM Type is requested should check which OAM Function Flags are set in the "Function Flags TLV" and look for the corresponding technology specific configuration TLV.
Additional corresponding sub-TLVs are as follows:
Moreover, if the CV flag is set, the CC flag MUST be set at the same time. The format of an MPLS-TP CV/CC message is shown in [BFD-CCCV] and it requires, together with the BFD control packet information, the "Unique MEP-ID of source of BFD packet". [MPLS-TP-IDENTIF] defines the composition of such identifier as:
<"Unique MEP-ID of source of BFD packet"> ::= <src_node_id><src_tunnel_num><lsp_num>
GMPLS signaling [RFC3473] uses a 5-tuple to uniquely identify an LSP within an operator's network. This tuple is composed of a Tunnel Endpoint Address, Tunnel_ID, Extended Tunnel ID, and Tunnel Sender Address and (GMPLS) LSP_ID.
Hence, the following mapping is used without the need of redefining a new TLV for MPLS-TP proactive CV purpose.
"Tunnel ID" and "Tunnel Sender Address" are included in the "SESSION" object [RFC3209], which is mandatory in both Path and Resv messages.
"LSP ID" will be the same on both directions and it is included in the "SENDER_TEMPLATE" object [RFC3209] which is mandatory in Path messages.
[Author's note: the same "Unique MEP-ID of source" will be likely required for Performance monitoring purposes. However for the moment in [MPLS-PM] it is stated: "The question of ACH TLV usage and the manner of supporting metadata such as authentication keys and node identifiers is deliberately omitted. These issues will be addressed in a future version of the document."]
The "BFD Configuration sub-TLV" (depicted below) is defined for BFD OAM specific configuration parameters. The "BFD Configuration sub-TLV" is carried as a sub-TLV of the "OAM Configuration TLV".
This TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (3) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Vers.| PHB |N|S|I| Reserved (set to all 0s) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub-TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type, the "BFD Configuration sub-TLV" (IANA to define).
Length: indicates the total length including sub-TLVs.
Version: identifies the BFD protocol version. If a node does not support a specific BFD version an error must be generated: "OAM Problem/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).
The "BFD Configuration sub-TLV" MUST include the following sub-TLVs in the Path message:
The "BFD Configuration sub-TLV" MUST include the following sub-TLVs in the Resv message:
Reserved: Reserved for future specification and set to 0.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (1) (IANA) | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type, the Local Discriminator sub-TLV (1) (IANA to define).
Length: indicates the TLV total length in octets.
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.
The "Negotiation Timer Parameters 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timer Neg. Type (2) (IANA) | Length = 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Acceptable Min. Asynchronous TX interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Acceptable Min. Asynchronous RX interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Echo TX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Detect. Mult.| Reserved (set to all 0s) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type, the "Negotiation Timer Parameters sub-TLV" (IANA to define).
Length: indicates the TLV total length in octets. (20)
Acceptable Min. Asynchronous TX interval: in case of S (symmetric) flag set in the "BFD Configuration sub-TLV", it expresses the desired time interval (in microseconds) at which the LER initiating the signaling intends to both transmit and receive BFD periodic control packets. If the receiving edge LSR 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 a edge LSR 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 edge LSRs can receive BFD periodic control packets. In case this value is greater than the "Acceptable Min. Asynchronous TX interval" received from the other edge LSR, such edge LSR 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 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 an error MUST be generated "Unsupported BFD TX rate interval".
Detection time multiplier: The negotiated transmit interval, multiplied by this value, provides the Detection Time for the receiving system in Asynchronous mode.
Reserved: Reserved for future specification and set to 0.
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) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type, the "BFD Authentication sub-TLV" (IANA to define).
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.
The "MPLS OAM PM Loss sub-TLV" depicted below is carried as a sub-TLV of the "OAM Configuration 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 (3) (IANA) | Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Vers.|E|C| | Reserved (set to all 0s) | PHB |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type, the "MPLS OAM PM Loss" (IANA to define).
Length: indicates the TLV total length in octets.
Version: indicates the Loss measurement protocol version.
Configuration Flags:
PHB: identifies the per-hop behavior of packets with loss information.
Measurement Interval: the time interval (in microseconds) at which Loss Measurement query messages MUST be sent on both directions. If the edge LSR receiving the Path message can not support such value, it can reply back with a higher interval.
Loss Threshold: the threshold value of lost packets over which protections MUST be triggered.
The "MPLS OAM PM Delay sub-TLV" depicted below is carried as a sub-TLV of the "OAM Configuration 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 Delay Type (4) (IANA) | Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Vers.| Flags | Reserved (set to all 0s) | PHB |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Delay Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type, the "MPLS OAM PM Delay" (IANA to define).
Length: indicates the TLV total length in octets.
Version: indicates the Delay measurement protocol version.
Configuration Flags:
PHB: - identifies the per-hop behavior of packets with delay information.
Measurement Interval: the time interval (in microseconds) at which Delay Measurement query messages MUST be sent on both directions. If the edge LSR receiving the Path message can not support such value, it can reply back with a higher interval.
Delay Threshold: the threshold value of measured delay (in microseconds) over which protections MUST be triggered.
[Author's note: TBD if we want to include the timestamp format negotiation as in [MPLS-PM] 4.2.5.]
The "MPLS OAM FMS sub-TLV" depicted below is carried as a sub-TLV of the "OAM Configuration 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (5) (IANA) | Length = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|D|L|C| Reserved (set all to 0s) |E| PHB |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Refresh Timer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type, the "MPLS OAM FMS" (IANA to define).
Length: indicates the TLV total length in octets.
Signal Flags: are used to enable the following signals:
Configuration Flags:
Refresh Timer: indicates the refresh timer (in microseconds) of fault indication messages. If the edge LSR receiving the Path message can not support such value, it can reply back with a higher interval.
This document specifies the following new TLV types:
sub-TLV types to be carried in the "BFD Configuration sub-TLV":
In addition to error values specified in [OAM-CONF-FWK] and [ETH-OAM] this document defines the following values for the "OAM Problem" Error Code:
The authors would like to thank David Allan, Lou Berger, Annamaria Fulignoli, Eric Gray, Andras Kern, David Jocha and David Sinicrope for their useful comments.
The signaling of OAM related parameters and the automatic establishment of OAM entities introduces additional security considerations to those discussed in [RFC3473]. In particular, a network element could be overloaded, if an attacker would request liveliness monitoring, with frequent periodic messages, for a high number of LSPs, targeting a single network element.
Security aspects will be covered in more detailed in subsequent versions of this document.