rfc9714v1.txt   rfc9714.txt 
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Internet Engineering Task Force (IETF) W. Cheng, Ed. Internet Engineering Task Force (IETF) W. Cheng, Ed.
Request for Comments: 9714 China Mobile Request for Comments: 9714 China Mobile
Category: Standards Track X. Min, Ed. Category: Standards Track X. Min, Ed.
ISSN: 2070-1721 ZTE Corp. ISSN: 2070-1721 ZTE Corp.
T. Zhou T. Zhou
Huawei Huawei
J. Dai J. Dai
FiberHome FiberHome
Y. Peleg Y. Peleg
Broadcom Broadcom
January 2025 February 2025
Encapsulation for MPLS Performance Measurement with the Alternate- Encapsulation for MPLS Performance Measurement with the Alternate-
Marking Method Marking Method
Abstract Abstract
This document defines the encapsulation for MPLS performance This document defines the encapsulation for MPLS performance
measurement with the Alternate-Marking Method, which performs flow- measurement with the Alternate-Marking Method, which performs flow-
based packet loss, delay, and jitter measurements on MPLS traffic. based packet loss, delay, and jitter measurements on MPLS traffic.
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flows. flows.
This document defines the encapsulation for MPLS performance This document defines the encapsulation for MPLS performance
measurement with the Alternate-Marking Method, which performs flow- measurement with the Alternate-Marking Method, which performs flow-
based packet loss, delay, and jitter measurements on the MPLS based packet loss, delay, and jitter measurements on the MPLS
traffic. The encapsulation defined in this document supports traffic. The encapsulation defined in this document supports
performance monitoring at the intermediate nodes and MPLS flow performance monitoring at the intermediate nodes and MPLS flow
identification at both transport and service layers. identification at both transport and service layers.
Note that in parallel to the work of this document, there is ongoing Note that in parallel to the work of this document, there is ongoing
work on MPLS Network Actions (MNA) [RFC9613]. The MPLS performance work, e.g., [MNA-PM-with-AMM], regarding MPLS Network Actions (MNAs)
measurement with the Alternate-Marking Method can also be achieved by [RFC9613]. The MPLS performance measurement with the Alternate-
MNA encapsulation. In addition, MNA will provide a broader use-case Marking Method can also be achieved by MNA encapsulation. In
applicability. That means the MNA encapsulation is expected to addition, MNA will provide a broader use-case applicability. That
provide a more advanced solution, when published as an RFC and it is means the MNA encapsulation is expected to provide a more advanced
agreed that this document will be made Historic at that time. solution. If [MNA-PM-with-AMM] is published as an RFC, the status of
this RFC will be reviewed and possibly changed to Historic.
2. Conventions Used in This Document 2. Conventions Used in This Document
2.1. Abbreviations 2.1. Abbreviations
ACL: Access Control List ACL: Access Control List
BoS: Bottom of Stack BoS: Bottom of Stack
cSPL: Composite Special Purpose Label, the combination of the cSPL: Composite Special Purpose Label, the combination of the
Extension Label (value 15) and an Extended Special Purpose Label Extension Label (value 15) and an Extended Special Purpose Label
DSCP: Differentiated Services Code Point DSCP: Differentiated Services Code Point
ECMP: Equal-Cost Multipath
ELC: Entropy Label Capability ELC: Entropy Label Capability
ERLD: Entropy Readable Label Depth ERLD: Entropy Readable Label Depth
eSPL: Extended Special Purpose Label, a special-purpose label that eSPL: Extended Special Purpose Label, a special-purpose label that
is placed in the label stack after the Extension Label (value 15) is placed in the label stack after the Extension Label (value 15)
FL: Flow-ID Label FL: Flow-ID Label
FLC: Flow-ID Label Capability FLC: Flow-ID Label Capability
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LSR: Label Switching Router LSR: Label Switching Router
MPLS: Multi-Protocol Label Switching MPLS: Multi-Protocol Label Switching
NMS: Network Management System NMS: Network Management System
PHP: Penultimate Hop Popping PHP: Penultimate Hop Popping
PM: Performance Measurement PM: Performance Measurement
PW: PseudoWire PW: Pseudowire
SFL: Synonymous Flow Label SFL: Synonymous Flow Label
SID: Segment ID SID: Segment ID
SR: Segment Routing SR: Segment Routing
TC: Traffic Class TC: Traffic Class
TTL: Time to Live TTL: Time to Live
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[RFC9017]. The FLI is defined in this document as value 18. [RFC9017]. The FLI is defined in this document as value 18.
The Traffic Class (TC) and Time To Live (TTL) fields of the XL and The Traffic Class (TC) and Time To Live (TTL) fields of the XL and
FLI MUST use the same values of the label immediately preceding the FLI MUST use the same values of the label immediately preceding the
XL. The Bottom of the Stack (BoS) bit [RFC3032] for the XL and FLI XL. The Bottom of the Stack (BoS) bit [RFC3032] for the XL and FLI
MUST be zero. If any XL or FLI processed by a node has the BoS bit MUST be zero. If any XL or FLI processed by a node has the BoS bit
set, the node MUST discard the packet and MAY log an error. set, the node MUST discard the packet and MAY log an error.
The Flow-ID Label (FL) is used as an MPLS flow identification The Flow-ID Label (FL) is used as an MPLS flow identification
[RFC8372]. Its value MUST be unique within the administrative [RFC8372]. Its value MUST be unique within the administrative
domain. The Flow-ID Label values MAY be allocated by an external NMS domain. The FL values MAY be allocated by an external NMS or
or controller based on the measurement object instances (such as LSP controller based on the measurement object instances (such as LSP or
or PW). There is a one-to-one mapping between a Flow-ID and a flow. PW). There is a one-to-one mapping between a Flow-ID and a flow.
The specific method on how to allocate the Flow-ID Label values is The specific method on how to allocate the FL values is described in
described in Section 5. Section 5.
The FL, preceded by a cSPL, can be placed either at the bottom or in The FL, preceded by a cSPL, can be placed either at the bottom or in
the middle, but not at the top, of the MPLS label stack, and it MAY the middle, but not at the top, of the MPLS label stack, and it MAY
appear multiple times within a label stack. Section 3.1 of this appear multiple times within a label stack. Section 3.1 of this
document provides several examples to illustrate the application of document provides several examples to illustrate the application of
FL in a label stack. The TTL for the FL MUST be zero to ensure that FL in a label stack. The TTL for the FL MUST be zero to ensure that
it is not used inadvertently for forwarding. The BoS bit for the FL it is not used inadvertently for forwarding. The BoS bit for the FL
depends on whether the FL is placed at the bottom of the MPLS label depends on whether the FL is placed at the bottom of the MPLS label
stack, i.e., the BoS bit for the FL is set only when the FL is placed stack, i.e., the BoS bit for the FL is set only when the FL is placed
at the bottom of the MPLS label stack. at the bottom of the MPLS label stack.
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* T(ype) bit is used to indicate the measurement type. When the T * T(ype) bit is used to indicate the measurement type. When the T
bit is set to 1, that means edge-to-edge performance measurement. bit is set to 1, that means edge-to-edge performance measurement.
When the T bit is set to 0, that means hop-by-hop performance When the T bit is set to 0, that means hop-by-hop performance
measurement. measurement.
Considering the FL is not used as a forwarding label, the repurposing Considering the FL is not used as a forwarding label, the repurposing
of the TC for the FL is feasible and viable. of the TC for the FL is feasible and viable.
3.1. Examples for Applying Flow-ID Label in a Label Stack 3.1. Examples for Applying Flow-ID Label in a Label Stack
Three examples of different layouts of the Flow-ID label (4 octets) Three examples of different layouts of the FL (4 octets) are
are illustrated as follows. Note that more examples may exist. illustrated as follows. Note that more examples may exist.
3.1.1. Layout of the Flow-ID Label when Applied to MPLS Transport 3.1.1. Layout of the Flow-ID Label when Applied to MPLS Transport
+----------------------+ +----------------------+
| LSP | | LSP |
| Label | | Label |
+----------------------+ <--+ +----------------------+ <--+
| Extension | | | Extension | |
| Label | | | Label | |
+----------------------+ |--- cSPL +----------------------+ |--- cSPL
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forwarding label", which implies that the penultimate Label Switching forwarding label", which implies that the penultimate Label Switching
Router (LSR) needs to follow the requirement of Section 4 in order to Router (LSR) needs to follow the requirement of Section 4 in order to
support this specification. If this is done, the egress LSR is support this specification. If this is done, the egress LSR is
excluded from the performance measurement. Therefore, when this excluded from the performance measurement. Therefore, when this
specification is in use, PHP should be disabled, unless the specification is in use, PHP should be disabled, unless the
penultimate LSR is known to have the necessary support and unless penultimate LSR is known to have the necessary support and unless
it's acceptable to exclude the egress LSR. it's acceptable to exclude the egress LSR.
Also note that in other examples of applying Flow-ID to MPLS Also note that in other examples of applying Flow-ID to MPLS
transport, one LSP label can be substituted by multiple SID labels in transport, one LSP label can be substituted by multiple SID labels in
the case of using SR Policy, and the combination of cSPL and Flow-ID the case of using SR Policy, and the combination of cSPL and FL can
label can be placed between SID labels, as specified in Section 6. be placed between SID labels, as specified in Section 6.
3.1.2. Layout of the Flow-ID Label when Applied to MPLS Service 3.1.2. Layout of the Flow-ID Label when Applied to MPLS Service
+----------------------+ +----------------------+
| LSP | | LSP |
| Label | | Label |
+----------------------+ +----------------------+
| Application | | Application |
| Label | | Label |
+----------------------+ <--+ +----------------------+ <--+
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| Flow-ID | | Flow-ID |
| Label | | Label |
+----------------------+ <= Bottom of stack +----------------------+ <= Bottom of stack
| | | |
| Payload | | Payload |
| | | |
+----------------------+ +----------------------+
Figure 4: Applying Flow-ID to both MPLS Transport and MPLS Service Figure 4: Applying Flow-ID to both MPLS Transport and MPLS Service
Note that for this example, the two Flow-ID Label values appearing in Note that for this example, the two FL values appearing in a label
a label stack must be different. In other words, the Flow-ID label stack must be different. In other words, the FL applied to the MPLS
applied to the MPLS transport and the Flow-ID label applied to the transport and the FL applied to the MPLS service must be different.
MPLS service must be different. Also, note that the two Flow-ID Also, note that the two FL values are independent of each other. For
label values are independent of each other. For example, two packets example, two packets can belong to the same VPN flow but different
can belong to the same VPN flow but different LSP flows, or two LSP flows, or two packets can belong to different VPN flows but the
packets can belong to different VPN flows but the same LSP flow. same LSP flow.
4. Procedures of Encapsulation, Look-Up, and Decapsulation 4. Procedures of Encapsulation, Look-Up, and Decapsulation
The procedures for Flow-ID label encapsulation, look-up, and The procedures for FL encapsulation, look-up, and decapsulation are
decapsulation are summarized as follows: summarized as follows:
* The MPLS ingress node [RFC3031] inserts the XL, FLI, and FL into * The MPLS ingress node [RFC3031] inserts the XL, FLI, and FL into
the MPLS label stack. At the same time, the ingress node sets the the MPLS label stack. At the same time, the ingress node sets the
Flow-ID Label value, the two color-marking bits, and the T bit, as FL value, the two color-marking bits, and the T bit, as defined in
defined in Section 3. Section 3.
* If edge-to-edge measurement is applied, i.e., the T bit is set to * If edge-to-edge measurement is applied, i.e., the T bit is set to
1, then only the MPLS ingress/egress node [RFC3031] is the 1, then only the MPLS ingress/egress node [RFC3031] is the
processing node; otherwise, all the MPLS nodes along the LSP are processing node; otherwise, all the MPLS nodes along the LSP are
the processing nodes. The processing node looks up the FL with the processing nodes. The processing node looks up the FL with
the help of the XL and FLI, and exports the collected data (such the help of the XL and FLI, and exports the collected data (such
as the Flow-ID, block counters, and timestamps) to an external as the Flow-ID, block counters, and timestamps) to an external
NMS/controller, referring to the Alternate-Marking Method. NMS/controller, referring to the Alternate-Marking Method.
Section 6 of [ALT-MARK] describes protocols for collected data Section 6 of [ALT-MARK] describes protocols for collected data
export; the details on how to export the collected data are export; the details on how to export the collected data are
outside the scope of this document. Note that while looking up outside the scope of this document. Note that while looking up
the Flow-ID label, the transit node needs to perform some deep the FL, the transit node needs to inspect beyond the label at the
labels inspection beyond the label (at the top of the label stack) top of the label stack used to make forwarding decisions.
used to make forwarding decisions.
* The processing node MUST pop the XL, FLI, and FL from the MPLS * The processing node MUST pop the XL, FLI, and FL from the MPLS
label stack when it needs to pop the preceding forwarding label. label stack when it needs to pop the preceding forwarding label.
The egress node MUST pop the whole MPLS label stack. This The egress node MUST pop the whole MPLS label stack. This
document doesn't introduce any new process to the decapsulated document doesn't introduce any new process to the decapsulated
packet. packet.
5. Procedures of Flow-ID Allocation 5. Procedures of Flow-ID Allocation
There are at least two ways of allocating Flow-ID. One way is to There are at least two ways of allocating Flow-ID. One way is to
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within an appropriate FRLD. To overcome this potential challenge, an within an appropriate FRLD. To overcome this potential challenge, an
implementation MAY allow the ingress node to place FL between SID implementation MAY allow the ingress node to place FL between SID
labels. This means that multiple identical FLs at different depths labels. This means that multiple identical FLs at different depths
MAY be interleaved with SID labels. When this occurs, sophisticated MAY be interleaved with SID labels. When this occurs, sophisticated
network planning may be needed, which is beyond the scope of this network planning may be needed, which is beyond the scope of this
document. document.
7. Equal-Cost Multipath Considerations 7. Equal-Cost Multipath Considerations
Analogous to what's described in Section 5 of [RFC8957], under Analogous to what's described in Section 5 of [RFC8957], under
conditions of Equal-Cost Multipath (ECMP), the introduction of the FL conditions of equal-cost multipath, the introduction of the FL may
may lead to the same problem that is caused by the Synonymous Flow lead to the same problem that is caused by the Synonymous Flow Label
Label (SFL) [RFC8957]. The two solutions proposed for SFL also apply (SFL) [RFC8957]. The two solutions proposed for SFL also apply here.
here. Specifically, adding FL to an existing flow may cause that Specifically, adding FL to an existing flow may cause that flow to
flow to take a different path. If the operator expects to resolve take a different path. If the operator expects to resolve this
this problem, they can choose to apply entropy labels [RFC6790] or problem, they can choose to apply entropy labels [RFC6790] or add FL
add FL to all flows. to all flows.
8. Security Considerations 8. Security Considerations
As specified in Section 7.1 of [RFC9341], "for security reasons, the As specified in Section 7.1 of [RFC9341], "for security reasons, the
Alternate-Marking Method MUST only be applied to controlled domains." Alternate-Marking Method MUST only be applied to controlled domains."
This requirement applies when the MPLS performance measurement with This requirement applies when the MPLS performance measurement with
Alternate-Marking Method is taken into account, which means the MPLS Alternate-Marking Method is taken into account, which means the MPLS
encapsulation and related procedures defined in this document MUST encapsulation and related procedures defined in this document MUST
only be applied to controlled domains; otherwise, the potential only be applied to controlled domains; otherwise, the potential
attacks discussed in Section 10 of [RFC9341] may be applied to the attacks discussed in Section 10 of [RFC9341] may be applied to the
deployed MPLS networks. deployed MPLS networks.
As specified in Section 3, the value of a Flow-ID label MUST be As specified in Section 3, the value of an FL MUST be unique within
unique within the administrative domain. In other words, the the administrative domain. In other words, the administrative domain
administrative domain is the scope of a Flow-ID label. The method is the scope of an FL. The method for achieving multi-domain
for achieving multi-domain performance measurement with the same performance measurement with the same FL is outside the scope of this
Flow-ID label is outside the scope of this document. The Flow-ID document. The FL MUST NOT be signaled and distributed outside the
label MUST NOT be signaled and distributed outside the administrative administrative domain. Improper configuration that allows the FL to
domain. Improper configuration that allows the Flow-ID label to be be passed from one administrative domain to another would result in
passed from one administrative domain to another would result in
Flow-ID conflicts. Flow-ID conflicts.
To prevent packets carrying Flow-ID labels from leaking from one To prevent packets carrying FLs from leaking from one domain to
domain to another, domain boundary nodes MUST deploy policies (e.g., another, domain boundary nodes MUST deploy policies (e.g., ACL) to
ACL) to filter out these packets. Specifically, at the sending edge, filter out these packets. Specifically, at the sending edge, the
the domain boundary node MUST filter out the packets that carry the domain boundary node MUST filter out the packets that carry the FLI
Flow-ID Label Indicator and are sent to other domains. At the and are sent to other domains. At the receiving edge, the domain
receiving edge, the domain boundary node MUST drop the packets that boundary node MUST drop the packets that carry the FLI and are from
carry the Flow-ID Label Indicator and are from other domains. Note other domains. Note that packet leakage is neither breaching privacy
that packet leakage is neither breaching privacy nor a source of DoS. nor a source of DoS.
9. IANA Considerations 9. IANA Considerations
IANA has assigned the following value in the "Extended Special- IANA has assigned the following value in the "Extended Special-
Purpose MPLS Label Values" registry within the "Special-Purpose Purpose MPLS Label Values" registry within the "Special-Purpose
Multiprotocol Label Switching (MPLS) Label Values" registry group: Multiprotocol Label Switching (MPLS) Label Values" registry group:
+=======+===============================+===========+ +=======+===============================+===========+
| Value | Description | Reference | | Value | Description | Reference |
+=======+===============================+===========+ +=======+===============================+===========+
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10.2. Informative References 10.2. Informative References
[ALT-MARK] Fioccola, G., Zhu, K., Graf, T., Nilo, M., and L. Zhang, [ALT-MARK] Fioccola, G., Zhu, K., Graf, T., Nilo, M., and L. Zhang,
"Alternate Marking Deployment Framework", Work in "Alternate Marking Deployment Framework", Work in
Progress, Internet-Draft, draft-ietf-ippm-alt-mark- Progress, Internet-Draft, draft-ietf-ippm-alt-mark-
deployment-02, 9 October 2024, deployment-02, 9 October 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-ippm- <https://datatracker.ietf.org/doc/html/draft-ietf-ippm-
alt-mark-deployment-02>. alt-mark-deployment-02>.
[MNA-PM-with-AMM]
Cheng, W., Min, X., Gandhi, R., and G. Mirsky, "MNA for
Performance Measurement with Alternate Marking Method",
Work in Progress, Internet-Draft, draft-cx-mpls-mna-
inband-pm-05, 21 October 2024,
<https://datatracker.ietf.org/doc/html/draft-cx-mpls-mna-
inband-pm-05>.
[RFC4026] Andersson, L. and T. Madsen, "Provider Provisioned Virtual [RFC4026] Andersson, L. and T. Madsen, "Provider Provisioned Virtual
Private Network (VPN) Terminology", RFC 4026, Private Network (VPN) Terminology", RFC 4026,
DOI 10.17487/RFC4026, March 2005, DOI 10.17487/RFC4026, March 2005,
<https://www.rfc-editor.org/info/rfc4026>. <https://www.rfc-editor.org/info/rfc4026>.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding", L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, DOI 10.17487/RFC6790, November 2012, RFC 6790, DOI 10.17487/RFC6790, November 2012,
<https://www.rfc-editor.org/info/rfc6790>. <https://www.rfc-editor.org/info/rfc6790>.
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RFC 9613, DOI 10.17487/RFC9613, August 2024, RFC 9613, DOI 10.17487/RFC9613, August 2024,
<https://www.rfc-editor.org/info/rfc9613>. <https://www.rfc-editor.org/info/rfc9613>.
Acknowledgements Acknowledgements
The authors acknowledge Loa Andersson, Tarek Saad, Stewart Bryant, The authors acknowledge Loa Andersson, Tarek Saad, Stewart Bryant,
Rakesh Gandhi, Greg Mirsky, Aihua Liu, Shuangping Zhan, Ming Ke, Wei Rakesh Gandhi, Greg Mirsky, Aihua Liu, Shuangping Zhan, Ming Ke, Wei
He, Ximing Dong, Darren Dukes, Tony Li, James Guichard, Daniele He, Ximing Dong, Darren Dukes, Tony Li, James Guichard, Daniele
Ceccarelli, Eric Vyncke, John Scudder, Gunter van de Velde, Roman Ceccarelli, Eric Vyncke, John Scudder, Gunter van de Velde, Roman
Danyliw, Warren Kumari, Murray Kucherawy, Deb Cooley, Zaheduzzaman Danyliw, Warren Kumari, Murray Kucherawy, Deb Cooley, Zaheduzzaman
Sarker, and Deboraha Brungard for their careful review and very Sarker, and Deborah Brungard for their careful review and very
helpful comments. helpful comments.
They also acknowledge Italo Busi and Chandrasekar Ramachandran for They also acknowledge Italo Busi and Chandrasekar Ramachandran for
their insightful MPLS-RT review and constructive comments. their insightful MPLS-RT review and constructive comments.
Additionally, the authors thank Dhruv Dhody for the English grammar Additionally, the authors thank Dhruv Dhody for the English grammar
review. review.
Contributors Contributors
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