| MPLS Working Group | E. Bellagamba |
| Internet-Draft | |
| Intended status: Standards Track | G. Mirsky |
| Expires: May 5, 2016 | Ericsson |
| L. Andersson | |
| Huawei Technologies | |
| P. Skoldstrom | |
| Acreo AB | |
| D. Ward | |
| Cisco | |
| J. Drake | |
| Juniper | |
| November 2, 2015 |
Configuration of Proactive Operations, Administration, and Maintenance (OAM) Functions for MPLS-based Transport Networks using LSP Ping
draft-ietf-mpls-lsp-ping-mpls-tp-oam-conf-15
This specification describes the configuration of proactive MPLS-TP Operations, Administration, and Maintenance (OAM) Functions for a given Label Switched Path (LSP) using a set of TLVs that are carried by the LSP-Ping protocol.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.
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This Internet-Draft will expire on May 5, 2016.
Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved.
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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 currently supported by MPLS. [RFC5860] defines the requirements for the OAM functionality of MPLS-TP.
This document describes the configuration of proactive MPLS-TP OAM Functions for a given Label Switched Path (LSP) using TLVs carried in LSP Ping [RFC4379]. In particular it specifies the mechanisms necessary to establish MPLS-TP OAM entities at the maintenance points for monitoring and performing measurements on an LSP, as well as defining information elements and procedures to configure proactive MPLS-TP OAM functions running between LERs. Initialization and control of on-demand MPLS-TP 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.
The Transport Profile of MPLS must, by definition [RFC5654], be capable of operating without a control plane. Therefore there are several options for configuring MPLS-TP OAM, without a control plane by either using an NMS or LSP Ping, or with a control plane using signaling protocols RSVP Traffic engineering (RSVP-TE) [RFC3209] and/or Targeted LDP [RFC5036].
Proactive MPLS-TP OAM is performed by set of protocols, Bi-directional Forwarding Detection (BFD) [RFC6428] for Continuity Check/Connectivity Verification, the delay measurement protocol (DM) [RFC6374], [RFC6375] for delay and delay variation (jitter) measurements, and the loss measurement (LM) protocol [RFC6374], [RFC6375] for packet loss and throughput measurements. Additionally, there is a number of Fault Management Signals that can be configured [RFC6427].
BFD is a protocol that provides low-overhead, fast 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 detect the continuity and mis-connection defects of MPLS-TP point-to-point and might also be extended to support point-to-multipoint label switched paths (LSPs).
The delay and loss measurements protocols [RFC6374] and [RFC6375] use a simple query/response model for performing both uni- and bi-directional measurements that allow the originating node to measure packet loss and delay in forward or forward and reverse directions. By timestamping and/or writing current packet counters to the measurement packets (four times, Transmit and Receive in both directions), current delays and packet losses can be calculated. By performing successive delay measurements, the delay and/or inter-packet delay variation (jitter) can be calculated. Current throughput can be calculated from the packet loss measurements by dividing the number of packets sent/received with the time it took to perform the measurement, given by the timestamp in LM header. Combined with a packet generator the throughput measurement can be used to measure the maximum capacity of a particular LSP. It should be noted that here we are not configuring on-demand throughput estimates based on saturating the connection as defined in [RFC6371]. Rather, we only enable the estimation of the current throughput based on loss measurements.
BFD - Bidirectional Forwarding Detection
DM - Delay Measurement
FMS - Fault Management Signal
G-ACh - Generic Associated Channel
LSP - Label Switched Path
LM - Loss Measurement
MEP - Maintenance Entity Group End Point
MPLS - Multi-Protocol Label Switching
MPLS-TP - MPLS Transport Profile
NMS - Network management System
PM - Performance Measurement
RSVP-TE - RSVP Traffic Engineering
TC - Traffic Class
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].
The MPLS-TP OAM tool set is described in the [RFC6669].
LSP Ping, or alternatively RSVP-TE [RFC7487], can be used to simply enable the different OAM functions, by setting the corresponding flags in the MPLS OAM Functions TLV (refer to Section 2.2). For a more detailed configuration, one may include sub-TLVs for the different OAM functions in order to specify various parameters in detail.
Typically intermediate nodes simply forward OAM configuration TLVs to the end-node without any processing or modification. At least one exception to this is if the FMS sub-TLV (refer to Section 2.2.9 ) is present. This sub-TLV MUST be examined even by intermediate nodes that support this extension. The sub-TLV MAY be present if a flag is set in the MPLS OAM Functions TLV.
For this specification, BFD MUST run in either one of the two modes:
In the simplest scenario, LSP Ping [RFC5884], or alternatively RSVP-TE [RFC7487], is used only to bootstrap a BFD session for an LSP, without any timer negotiation.
Timer negotiation can be performed either in subsequent BFD control messages (in this case the operation is similar to LSP Ping based bootstrapping described in [RFC5884]) or directly in the LSP-Ping configuration messages.
When BFD Control packets are transported in the ACH encapsulation, 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 (refer to Section 2.2.1) 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 pre-shared key/password is desired (i.e. authentication and not only error detection), the BFD Authentication sub-TLV (refer to Section 2.2.4) 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 pre-shared key/ password that should be used for this particular session. How the key exchange is performed is out of scope of this document.
It is possible to configure Performance Monitoring functionalities such as Loss, Delay, Delay/Interpacket Delay variation (jitter), and Throughput as described in [RFC6374].
When configuring Performance Monitoring functionalities, it is possible to choose either the default configuration, by only setting the respective flags in the MPLS OAM functions TLV, or a customized configuration. To customize the configuration, one would set the respective flags in the MPLS OAM functions TLV and include the respective Loss and/or Delay sub-TLVs.
By setting the PM Loss flag in the MPLS OAM Functions TLV and including the PM Loss sub-TLV (refer to Section 2.2.7) one can configure the measurement interval and loss threshold values for triggering protection.
Delay measurements are configured by setting the PM Delay flag in the MPLS OAM Functions TLV and including the PM Delay sub-TLV (refer to Section 2.2.8) one can configure the measurement interval and the delay threshold values for triggering protection.
To configure Fault Management Signals (FMS) and their refresh time, the FMS flag in the MPLS OAM Functions TLV MUST be set and the FMS sub-TLV MUST be included. When configuring FMS, an implementation can enable the default configuration by setting the FMS flag in the OAM Function Flags sub-TLV. In order to modify the default configuration, the MPLS OAM FMS sub-TLV MUST be included.
If an intermediate point is meant to originate fault management signal messages, this means that such an intermediate point is associated with a Server MEP through a co-located MPLS-TP client/server adaptation function, and the Fault Management subscription flag in the MPLS OAM FMS sub-TLV has been set as indication of the request to create the association at each intermediate node of the client LSP. The corresponding Server MEP needs to be configured by its own LSP-ping session or, alternatively, via a Network Management system (NMS) or RSVP-TE.
The MPLS OAM Functions TLV presented in Figure 1 is carried as a TLV of the MPLS Echo Request/Reply messages [RFC4379].
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MPLS OAM Func. Type (TBA1) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MPLS OAM Function Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ sub-TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: MPLS OAM Functions TLV format
The MPLS OAM Functions TLV contains MPLS OAM Function Flags field. The MPLS OAM Function Flags indicates which OAM functions should be activated as well as OAM function specific sub-TLVs with configuration parameters for the particular function.
Type: indicates the MPLS OAM Functions TLV Section 4.
Length: the length of the MPLS OAM Function Flags field including the total length of the sub-TLVs in octets.
MPLS OAM Function Flags: a bitmap numbered from left to right as shown in the Figure 2. These flags are managed by IANA (refer to Section 4.2). Flags defined in this document are presented in Table 2. Undefined flags MUST be set to zero and unknown flags MUST be ignored. The flags indicate what OAM is being configured and direct the presence of optional sub-TLVs as set out 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |C|V|F|L|D|T| Unassigned (MBZ) |R| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: MPLS OAM Function Flags format
Sub-TLVs corresponding to the different flags are as follows. No meaning should be attached to the order of sub-TLVs.
If all flags in the MPLS OAM Function Flags field have the same value of zero, that MUST be interpreted as the MPLS OAM Functions TLV not present in the MPLS Echo Request. If more than one MPLS OAM Functions TLV is present in the MPLS Echo request packet, then the first TLV SHOULD be processed and the rest be ignored. Any parsing error within nested sub-TLVs that is not specified in Section 3 SHOULD be treated as described in [RFC4379].
The BFD Configuration sub-TLV, depicted in Figure 3, is defined for BFD OAM specific configuration parameters. The "BFD Configuration sub-TLV" is carried as a sub-TLV of the "OAM Functions 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BFD Conf. sub-Type (100) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Vers.|N|S|I|G|U|B| Reserved (set to all 0s) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ sub-TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: BFD Configuration sub-TLV format
Sub-type: indicates a new sub-type, the BFD Configuration sub-TLV (value 100).
Length: indicates the length of the Value field in octets.
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".
BFD Negotiation (N): If set timer negotiation/re-negotiation via BFD Control Messages is enabled, when cleared it is disabled and timer configuration is achieved using Negotiation Timer Parameters sub-TLV as described in Section 2.2.3.
Symmetric session (S): If set the BFD session MUST use symmetric timing values. If cleared the BFD session MAY use any timing values either negotiated or explicitly configured.
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). If the egress LSR does not support BFD Authentication an error MUST be generated: "OAM Problem/BFD Authentication unsupported". If the Integrity flag is clear, then Authentication MUST NOT be used.
Encapsulation Capability (G): if set, it shows the capability of encapsulating BFD messages into G-ACh channel. If both the G bit and U bit are set, configuration gives precedence to the G bit.
Encapsulation Capability (U): if set, it shows the capability of encapsulating BFD messages into IP/UDP packets. If both the G bit and U bit are set, configuration gives precedence to the G bit.
If the egress LSR does not support any of the ingress LSR Encapsulation Capabilities an error MUST be generated: "OAM Problem/Unsupported BFD Encapsulation format".
Bidirectional (B): if set, it configures BFD in the Bidirectional mode. If it is not set it configures BFD in unidirectional mode. In the second case, the source node does not expect any Discriminator values back from the destination node.
Reserved: Reserved for future specification and set to 0 on transmission and ignored when received.
The BFD Configuration sub-TLV MUST include the following sub-TLVs in the MPLS Echo Request message:
The BFD Configuration sub-TLV MUST include the following sub-TLVs in the MPLS Echo Reply message:
The Local Discriminator sub-TLV is carried as a sub-TLV of the "BFD Configuration sub-TLV" and is depicted in Figure 4.
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Locl. Discr. sub-Type (101) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local Discriminator | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Local Discriminator sub-TLV format
Type: indicates a new type, the "Local Discriminator sub-TLV" (value 101).
Length: indicates the length of the Value field in octets . (4)
Local Discriminator: A nonzero discriminator value that is unique in the context of the transmitting system that generates it. It is 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 in Figure 5.
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Nego. Timer sub-type (102) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Acceptable Min. Asynchronous TX interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Acceptable Min. Asynchronous RX interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Required Echo TX Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Negotiation Timer Parameters sub-TLV format
Sub-type: indicates a new sub-type, the Negotiation Timer Parameters sub-TLV (value 102).
Length: indicates the length of the Value field in octets (12).
Acceptable Min. Asynchronous TX interval: in case of S (symmetric) flag set in the BFD Configuration sub-TLV, defined in Section 2.2.1, it expresses the desired time interval (in microseconds) at which the ingress LER intends to both transmit and receive BFD periodic control packets. If the receiving edge LSR cannot support such value, it SHOULD reply 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, Figure 3, 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 value of 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 cannot support this value the "Unsupported BFD TX Echo rate interval" error MUST be generated. By default the value is set to 0.
The "BFD Authentication sub-TLV" is carried as a sub-TLV of the "BFD Configuration sub-TLV" and is depicted in Figure 6.
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. sub-type (103) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auth Type | Auth Key ID | Reserved (0s) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: BFD Authentication sub-TLV format
Sub-type: indicates a new type, the BFD Authentication sub-TLV (value 103).
Length: indicates the length of the Value field in octets (4).
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. If the egress LSR does not support this Auth Key ID an "OAM Problem/Mismatch of BFD Authentication Key ID" error MUST be generated.
Reserved: Reserved for future specification and set to 0 on transmission and ignored when received.
An implementation MAY change mode of authentication if an operator re-evaluates the security situation in and around the administrative domain. If BFD Authentication sub-TLV used for a BFD session in Up state, then the Sender of the MPLS LSP Echo Request SHOULD ensure that old and new modes of authentication, i.e. combination of Auth.Type and Auth. Key ID, are used to send and receive BFD control packets, until the Sender can confirm that its peer has switched to the new authentication.
The Traffic Class sub-TLV is carried as a sub-TLV of the "BFD Configuration sub-TLV" and "Fault Management Signal sub-TLV" Section 2.2.9 and is depicted in Figure 7.
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Traffic Class sub-Type (104) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TC | Reserved (set to all 0s) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Traffic Class sub-TLV format
Type: indicates a new type, the "Traffic Class sub-TLV" (value 104).
Length: indicates the length of the Value field in octets . (4)
TC: Identifies the Traffic Class (TC) [RFC5462] for periodic continuity monitoring messages or packets with fault management information.
If the TC sub-TLV is present, then the sender of any periodic continuity monitoring messages or packets with fault management information on the LSP, with a FEC that corresponds to the FEC for which fault detection is being performed, MUST use the value contained in the TC field of the sub-TLV as the value of the TC field in the top label stack entry of the MPLS label stack. If the TC sub-TLV is absent from either "BFD Configuration sub-TLV" or "Fault Management Signal sub-TLV", then selection of the TC value is local decision.
If the MPLS OAM Functions TLV has any of the L (Loss), D (Delay) and T (Throughput) flag set, the Performance Measurement sub-TLV MUST be present. Failure to include the correct sub-TLVs MUST result in an "OAM Problem/ Configuration Error" error being generated.
The Performance Measurement sub-TLV provides the configuration information mentioned in Section 7 of [RFC6374]. It includes support for the configuration of quality thresholds and, as described in [RFC6374], "the crossing of which will trigger warnings or alarms, and result in reporting and exception notification will be integrated into the system-wide network management and reporting framework."
In case the values need to be different than the default ones, the Performance Measurement sub-TLV MAY include the following sub-TLVs:
The Performance Measurement sub-TLV depicted in Figure 8 is carried as a sub-TLV of the MPLS OAM Functions 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 (200) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PM Configuration Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ sub-TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Performance Measurement sub-TLV format
Sub-type: indicates a new sub-type, the Performance Management sub-TLV" (value 200).
Length: indicates the length of the Value field in octets, including PM Configuration Flags and optional 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |D|L|J|Y|K|C| Reserved (set to all 0s) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: Performance Measurement sub-TLV format
PM Configuration Flags, format is presented in Figure 9, for the specific function description please refer to [RFC6374]:
Reserved: Reserved for future specification and set to 0 on transmission and ignored when received.
The PM Loss Measurement sub-TLV depicted in Figure 10 is carried as a sub-TLV of the Performance Measurement 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 sub-type (201) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OTF |T|B| Reserved (set to all 0s) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Measurement Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Test Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Loss Threshold | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: PM Loss Measurement sub-TLV format
Sub-type: indicates a new sub-type, the PM Loss Measurement sub-TLV (value 201).
Length: indicates the length of the Value field in octets (16).
OTF: Origin Timestamp Format of the Origin Timestamp field described in [RFC6374]. By default it is set to IEEE 1588 version 1. If the egress LSR cannot support this value an "OAM Problem/Unsupported Timestamp Format" error MUST be generated.
Configuration Flags, please refer to [RFC6374] for further details:
Reserved: Reserved for future specification and set to 0 on transmission and ignored when received.
Measurement Interval: the time interval (in milliseconds) at which Loss Measurement query messages MUST be sent on both directions. If the edge LSR receiving the Path message cannot support such value, it SHOULD reply with a higher interval. By default it is set to (100) as per [RFC6375].
Test Interval: test messages interval in milliseconds as described in [RFC6374]. By default it is set to (10) as per [RFC6375].
Loss Threshold: the threshold value of measured lost packets per measurement over which action(s) SHOULD be triggered.
The "PM Delay Measurement sub-TLV" depicted in Figure 11 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 Delay Type (202) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OTF |T|B| Reserved (set to all 0s) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Measurement Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Test Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Delay Threshold | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: PM Delay Measurement sub-TLV format
Sub-type: indicates a new sub-type, the "PM Delay Measurement sub-TLV" (value 202).
Length: indicates the length of the Value field in octets (16).
OTF: Origin Timestamp Format of the Origin Timestamp field described in [RFC6374]. By default it is set to IEEE 1588 version 1. If the egress LSR cannot support this value, an "OAM Problem/Unsupported Timestamp Format" error MUST be generated.
Configuration Flags, please refer to [RFC6374] for further details:
Reserved: Reserved for future specification and set to 0 on transmission and ignored when received.
Measurement Interval: the time interval (in milliseconds) at which Delay Measurement query messages MUST be sent on both directions. If the edge LSR receiving the Path message cannot support such value, it can reply with a higher interval. By default it is set to (1000) as per [RFC6375].
Test Interval: test messages interval (in milliseconds) as described in [RFC6374]. By default it is set to (10) as per [RFC6375].
Delay Threshold: the threshold value of measured two-way delay (in milliseconds) over which action(s) SHOULD be triggered.
The FMS sub-TLV depicted in Figure 12 is carried as a sub-TLV of the MPLS OAM Configuration sub-TLV. When both working and protection paths are configured, both LSPs SHOULD be configured with identical settings of the E flag, T flag, and the refresh timer. An implementation MAY configure the working and protection LSPs with different settings of these fields in case of 1:N protection.
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | FMS sub-type (300) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E|S|T| Reserved | Refresh Timer | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ sub-TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Fault Management Signal sub-TLV format
Sub-type: indicates a new sub-type, the FMS sub-TLV (value 300).
Length: indicates the length of the Value field in octets.
FMS Signal Flags are used to enable the FMS signals at end point MEPs and the Server MEPs of the links over which the LSP is forwarded. In this document only the S flag pertains to Server MEPs.
The following flags are defined:
Refresh Timer: indicates the refresh timer of fault indication messages, in seconds. The value MUST be between 1 to 20 seconds as specified for the Refresh Timer field in [RFC6427]. If the edge LSR receiving the Path message cannot support the value it SHOULD reply with a higher timer value.
FMS sub-TLV MAY include Traffic Class sub-TLV Section 2.2.5. If TC sub-TLV is present, the value of the TC field MUST be used as the value of the TC field of an MPLS label stack entry for FMS messages. If the TC sub-TLV is absent, then selection of the TC value is local decision.
The Source MEP-ID sub-TLV depicted in Figure 13 is carried as a sub-TLV of the MPLS OAM Functions TLV.
Note that support of ITU IDs is out-of-scope.
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source MEP-ID sub-type (400) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Node ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel ID | LSP ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: Source MEP-ID sub-TLV format
Sub-type: indicates a new sub-type, the Source MEP-ID sub-TLV (value 400).
Length: indicates the length of the Value field in octets (8).
Source Node ID: 32-bit node identifier as defined in [RFC6370].
Tunnel ID: a 16-bit unsigned integer unique to the node as defined in [RFC6370].
LSP ID: a 16-bit unsigned integer unique within the Tunnel_ID as defined in [RFC6370].
This is the summary of Return Codes [RFC4379] defined in this document:
Ingress LSR MAY combine multiple MPLS OAM configuration TLVs and sub-TLVs into single MPLS echo request. In case an egress LSR doesn't support any of the requested modes it MUST set the return code to report the first unsupported mode in the list of TLVs and sub-TLVs. And if any of the requested OAM configuration is not supported the egress LSR SHOULD NOT process OAM Configuration TLVs and sub-TLVs listed in the MPLS echo request.
IANA maintains the Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters registry, and within that registry a sub-registry for TLVs and sub-TLVs.
IANA is requested a new TLV from the standards action range (0-16383) and sub-TLVs as follows from this sub-registry, called "Sub-TLVs for TLV [TBA1]".
Registration procedures for Sub-TLVs from ranges 0-16383 and 32768-49161 are by Standards Action, and from ranges 16384-31743 and 49162-64511 are through Specification Required (Experimental RFC Needed).
| Type | Sub-type | Value Field | Reference |
|---|---|---|---|
| TBA1 | MPLS OAM Functions | This document | |
| 100 | BFD Configuration | This document | |
| 101 | BFD Local Discriminator | This document | |
| 102 | BFD Negotiation Timer Parameters | This document | |
| 103 | BFD Authentication | This document | |
| 104 | Traffic Class | This document | |
| 200 | Performance Measurement | This document | |
| 201 | PM Loss Measurement | This document | |
| 202 | PM Delay Measurement | This document | |
| 300 | Fault Management Signal | This document | |
| 400 | Source MEP-ID | This document |
IANA is requested to create a new registry called the "MPLS OAM Function Flags" registry . Assignments of bit positions 0 through 31 are via Standards Action. The new registry to be populated as follows.
| Bit Position | MPLS OAM Function Flag | Description |
|---|---|---|
| 0 | C | Continuity Check (CC) |
| 1 | V | Connectivity Verification (CV) |
| 2 | F | Fault Management Signal (FMS) |
| 3 | L | Performance Measurement/Loss (PM/Loss) |
| 4 | D | Performance Measurement/Delay (PM/Delay) |
| 5 | T | Throughput Measurement |
| 6-30 | Unassigned (Must be zero) | |
| 31 | Reserved |
IANA maintains a registry "Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters" registry, and within that registry a sub-registry "Return Codes".
IANA is requested to assign new Return Codes from the Standards Action range (0-191) as follows:
| Error Value Sub-codes | Description | Reference |
|---|---|---|
| TBA3 | OAM Problem/Unsupported BFD Version | This document |
| TBA4 | OAM Problem/Unsupported BFD Encapsulation format | This document |
| TBA5 | OAM Problem/Unsupported BFD Authentication Type | This document |
| TBA6 | OAM Problem/Mismatch of BFD Authentication Key ID | This document |
| TBA7 | OAM Problem/Unsupported Timestamp Format | This document |
| TBA8 | OAM Problem/Unsupported Delay Mode | This document |
| TBA9 | OAM Problem/Unsupported Loss Mode | This document |
| TBA10 | OAM Problem/Delay variation unsupported | This document |
| TBA11 | OAM Problem/Dyadic mode unsupported | This document |
| TBA12 | OAM Problem/Loopback mode unsupported | This document |
| TBA13 | OAM Problem/Combined mode unsupported | This document |
| TBA14 | OAM Problem/Fault management signaling unsupported | This document |
| TBA15 | OAM Problem/Unable to create fault management association | This document |
The authors would like to thank Nobo Akiya, David Allan and Adrian Farrel for their thorough reviews and insightful comments.
The signaling of OAM related parameters and the automatic establishment of OAM entities introduces additional security considerations to those discussed in [RFC4379]. In particular, a network element could be overloaded if an attacker were to request high frequency liveliness monitoring of a large number of LSPs, targeting a single network element. Implementations must be made cognizant of available OAM resources and MAY refuse new OAM configurations that would overload a node. Additionally, policies to manage OAM resources may be used to provide some fairness in OAM resource distribution among monitored LSPs.
Security of OAM protocols configured with extensions to LSP Ping described in this document are discussed in [RFC5880], [RFC5884], [RFC6374], [RFC6427], and [RFC6428].
In order that the configuration of OAM functionality can be achieved securely through the techniques described in this document, security mechanisms must already be in place and operational for LSP Ping. Thus the exchange of security parameters (such as keys) for use in securing OAM is outside the scope of this document and is assumed to use an off-line mechanism or an established secure key-exchange protocol.
Additional discussion of security for MPLS protocols can be found in [RFC5920].