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<rfc docName="draft-ietf-mpls-sfl-framework-11" category="std"> <rfc xmlns:xi="http://www.w3.org/2001/XInclude" ipr="trust200902"
docName="draft-ietf-mpls-sfl-framework-11" number="8957" obsoletes=""
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<front> <front>
<title abbrev="MPLS FL">Synonymous Flow Label Framework</title> <title abbrev="MPLS FL">Synonymous Flow Label Framework</title>
<seriesInfo name="RFC" value="8957"/>
<author initials="S." surname="Bryant" fullname="Stewart Bryant"> <author initials="S." surname="Bryant" fullname="Stewart Bryant">
<organization>Futurewei Technologies Inc</organization> <organization>Futurewei Technologies Inc.</organization>
<address> <address>
<email>sb@stewartbryant.com</email> <email>sb@stewartbryant.com</email>
</address> </address>
</author> </author>
<author initials="M." surname="Chen" fullname="Mach Chen">
<author initials="M." surname="Chen" fullname="Mach(Guoyi) Chen">
<organization>Huawei</organization> <organization>Huawei</organization>
<address> <address>
<email>mach.chen@huawei.com</email> <email>mach.chen@huawei.com</email>
</address> </address>
</author> </author>
<author initials="G." surname="Swallow" fullname="George Swallow"> <author initials="G." surname="Swallow" fullname="George Swallow">
<organization>Southend Technical Center</organization> <organization>Southend Technical Center</organization>
<address> <address>
<email>swallow.ietf@gmail.com</email> <email>swallow.ietf@gmail.com</email>
</address> </address>
skipping to change at line 48 skipping to change at line 47
<address> <address>
<email>ssivabal@ciena.com</email> <email>ssivabal@ciena.com</email>
</address> </address>
</author> </author>
<author initials="G." surname="Mirsky" fullname="Gregory Mirsky"> <author initials="G." surname="Mirsky" fullname="Gregory Mirsky">
<organization>ZTE Corp.</organization> <organization>ZTE Corp.</organization>
<address> <address>
<email>gregimirsky@gmail.com</email> <email>gregimirsky@gmail.com</email>
</address> </address>
</author> </author>
<date year="2021" month="January"/>
<date year="2020" month="October" day="02"/>
<workgroup>MPLS Working Group</workgroup> <workgroup>MPLS Working Group</workgroup>
<abstract> <abstract>
<t>RFC 8372 ("MPLS Flow Identification Considerations") describes the
<t>RFC 8372 (MPLS Flow Identification Considerations) describes the requirement requirement for introducing flow identities within the MPLS
for architecture. This document describes a method of accomplishing this by
introducing using a technique called "Synonymous Flow Labels" in which labels that
flow identities within the MPLS architecture. This document mimic the behavior of other labels provide the identification service.
describes a method of accomplishing this by using a technique called These identifiers can be used to trigger per-flow operations on the
Synonymous Flow Labels in which labels which mimic the behaviour of packet at the receiving label switching router.</t>
other labels provide the identification service. These identifiers
can be used to trigger per-flow operations on the packet at
the receiving label switching router.</t>
</abstract> </abstract>
</front> </front>
<middle> <middle>
<section anchor="introduction" numbered="true" toc="default">
<section anchor="introduction" title="Introduction"> <name>Introduction</name>
<t><xref target="RFC8372" format="default"/> ("MPLS Flow Identification
<t><xref target="RFC8372"/> (MPLS Flow Identification Considerations) describes Considerations") describes the requirement for introducing
the requirement for introducing
flow identities within the MPLS architecture. flow identities within the MPLS architecture.
This document describes a method of providing the required identification by usi ng a This document describes a method of providing the required identification by usi ng a
technique called Synonymous Flow Labels (SFL) in technique called "Synonymous Flow Labels (SFLs)" in
which labels which mimic the behaviour of other MPLS labels provide the which labels that mimic the behavior of other MPLS labels provide the
identification service. These identifiers can be used to trigger identification service. These identifiers can be used to trigger
per-flow operations on the packet at the receiving label switching per-flow operations on the packet at the receiving label switching
router.</t> router.</t>
</section>
</section> <section anchor="requirements-language" numbered="true" toc="default">
<section anchor="requirements-language" title="Requirements Language"> <name>Requirements Language</name>
<t>
<t>The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>",
“SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
“OPTIONAL” in this document are to be interpreted as described in NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>",
BCP 14 <xref target="RFC2119"/> <xref target="RFC8174"/> when, and only when, th "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
ey appear in all "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to
capitals, as shown here.</t> be interpreted as
described in BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
</section> when, and only when, they appear in all capitals, as shown here.
<section anchor="SFL" title="Synonymous Flow Labels"> </t>
</section>
<t>An SFL is defined to be a label that causes exactly the same <section anchor="SFL" numbered="true" toc="default">
behaviour at the egress Label Edge Router (LER) as the label it <name>Synonymous Flow Labels</name>
replaces, except that it also causes one or more additional actions that have be <t>An SFL is defined to be a label that causes exactly the same
en previously agreed between the peer LERs to be executed behavior at the egress Label Edge Router (LER) as the label it
on the packet. There are many possible additional actions such as replaces, except that it also causes one or more additional actions that have
the measurement of the number of received packets in a flow, been previously agreed between the peer LERs to be executed
triggering an IP Flow Information Export (IPFIX) <xref target="RFC7011"/> captur on the packet. There are many possible additional actions, such as
e, triggering other types of Deep Packet measuring the number of received packets in a flow,
Inspection, or identification of the packet source. In, for example, triggering an IP Flow Information Export (IPFIX) <xref target="RFC7011"
format="default"/> capture, triggering other types of deep packet
inspection, or identifying the packet source. For example, in
a Performance Monitoring (PM) application, the agreed action could be a Performance Monitoring (PM) application, the agreed action could be
the recording of the receipt of the packet by incrementing a packet recording the receipt of the packet by incrementing a packet
counter. This is a natural action in many MPLS implementations, and counter. This is a natural action in many MPLS implementations, and
where supported this permits the implementation of high quality where supported, this permits the implementation of high-quality
packet loss measurement without any change to the packet forwarding packet loss measurement without any change to the packet-forwarding
system.</t> system.</t>
<t>To illustrate the use of this technology, we start by considering
<t>To illustrate the use of this technology, we start by considering the case where there is an <tt>application</tt> label in the MPLS label stack.
the case where there is an “application” label in the MPLS label stack.
As a first example, let us consider a As a first example, let us consider a
pseudowire (PW) <xref target="RFC3985"/> on which it is desired to make pseudowire (PW) <xref target="RFC3985" format="default"/> on which it is desired to make
packet loss measurements. Two labels, synonymous with the PW labels, are obtaine d packet loss measurements. Two labels, synonymous with the PW labels, are obtaine d
from the egress terminating provider edge (T-PE). By alternating from the egress terminating provider edge (T-PE). By alternating
between these SFLs and using them in place of the PW label, the PW between these SFLs and using them in place of the PW label, the PW
packets may be batched for counting without any impact on the PW packets may be batched for counting without any impact on the PW
forwarding behavior <xref target="RFC8321"/> (note that strictly only one SFL is forwarding behavior <xref target="RFC8321" format="default"/> (note that
needed in strictly only one SFL is needed in
this application, but that is an optimization that is a matter for this application, but that is an optimization that is a matter for
the implementor). The method of obtaining these additional the implementor). The method of obtaining these additional
labels is outside the scope of this text, however, labels is outside the scope of this text; however,
one control protocol that provides a method of obtaining SFLs is described in one control protocol that provides a method of obtaining SFLs is described in
<xref target="I-D.bryant-mpls-sfl-control"/>.</t> <xref target="I-D.bryant-mpls-sfl-control" format="default"/>.</t>
<t>Next, consider an MPLS application that is multipoint to point, such as
<t>Now consider an MPLS application that is multi-point to point such as a VPN. Here, it is necessary to identify a packet batch from a
a VPN. Here it is necessary to identify a packet batch from a
specific source. This is achieved by making the SFLs source specific source. This is achieved by making the SFLs source
specific, so that batches from one source are marked differently from specific, so that batches from one source are marked differently from
batches from another source. The sources all operate independently batches from another source. The sources all operate independently
and asynchronously from each other, independently coordinating with and asynchronously from each other, independently coordinating with
the destination. Each ingress LER is thus able to establish its own SFL the destination. Each ingress LER is thus able to establish its own SFL
to identify the sub-flow and thus enable PM per flow.</t> to identify the subflow and thus enable PM per flow.</t>
<t>Finally, we need to consider the case where there is no MPLS
<t>Finally we need to consider the case where there is no MPLS application label such as occurs when sending IP over a Label Switched Path
application label such as occurs when sending IP over an LSP, i.e. there is a si (LSP), i.e., there is a single label in the MPLS label stack. In
ngle label in the MPLS label stack. In this case, introducing an SFL that was synonymous with the LSP label
this case introducing an SFL that was synonymous with the LSP label
would introduce network-wide forwarding state. This would not be would introduce network-wide forwarding state. This would not be
acceptable for scaling reasons. We therefore have no choice but to acceptable for scaling reasons. Therefore, we have no choice but to
introduce an additional label. Where penultimate hop popping (PHP) introduce an additional label. Where penultimate hop popping (PHP)
is in use, the semantics of this additional label can be similar to is in use, the semantics of this additional label can be similar to
the LSP label. Where PHP is not in use, the semantics are similar to the LSP label. Where PHP is not in use, the semantics are similar to
an MPLS explicit NULL <xref target="RFC3032"/>. In both of these cases the labe an MPLS Explicit NULL <xref target="RFC3032" format="default"/>. In both of
l has the these cases, the label has the additional semantics of the SFL.</t>
additional semantics of the SFL.</t> <t>Note that to achieve the goals set out above, SFLs need to be
<t>Note that to achieve the goals set out above, SFLs need to be
allocated from the platform label table.</t> allocated from the platform label table.</t>
</section>
</section> <section anchor="user-service-traffic-in-the-data-plane" numbered="true" toc
<section anchor="user-service-traffic-in-the-data-plane" title="User Service Tra ="default">
ffic in the Data Plane"> <name>User Service Traffic in the Data Plane</name>
<t>As noted in <xref target="SFL" format="default"/>, it is necessary to
<t>As noted in <xref target="SFL"/> it is necessary to consider two cases:</t> consider two cases:</t>
<ol spacing="normal" type="1">
<t><list style="numbers"> <li>Application label is present</li>
<t>Application label is present</t> <li>Single-label stack</li>
<t>Single label stack</t> </ol>
</list></t> <section anchor="ALP" numbered="true" toc="default">
<name>Application Label Present</name>
<section anchor="ALP" title="Application Label Present"> <t><xref target="Figure1" format="default"/> shows the case in which
both an LSP label and an application
<t><xref target="Figure1"/> shows the case in which both an LSP label and an app
lication
label are present in the MPLS label stack. Traffic with no SFL label are present in the MPLS label stack. Traffic with no SFL
function present runs over the “normal” stack, and SFL-enabled flows function present runs over the <tt>normal</tt> stack, and SFL-enabled flows
run over the SFL stack with the SFL used to indicate the packet run over the SFL stack with the SFL used to indicate the packet
batch.</t> batch.</t>
<figure anchor="Figure1">
<figure title="Use of Synonymous Labels In A Two Label MPLS Label Stack" anchor= <name>Use of Synonymous Labels in a Two-Label MPLS Label Stack</name>
"Figure1"><artwork><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
+-----------------+ +-----------------+ +-----------------+ +-----------------+
| LSP | | LSP | | LSP | | LSP |
| Label | | Label | | Label | | Label |
| (May be PHPed) | | (May be PHPed) | | (May be PHPed) | | (May be PHPed) |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
| | | | | | | |
| Application | | Synonymous Flow | | Application | | Synonymous Flow |
| Label | | Label | | Label | | Label |
+-----------------+ <= BoS +-----------------+ <= Bottom of stack +-----------------+ <= BoS +-----------------+ <= Bottom of Stack
| | | | | | | |
| Payload | | Payload | | Payload | | Payload |
| | | | | | | |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
"Normal" Label Stack Label Stack with SFL "Normal" Label Stack Label Stack with SFL
]]></artwork></figure> ]]></artwork>
</figure>
<t>At the egress LER the LSP label is popped (if present). <t>At the egress LER, the LSP label is popped (if present). Then, the
Then the SFL SFL is processed executing both the synonymous function and the
is processed executing both the synonymous function and the corresponding applic corresponding application function.</t>
ation function.</t> <section anchor="TTLandTC" numbered="true" toc="default">
<name>Setting TTL and the Traffic Class Bits</name>
<section anchor="TTLandTC" title="Setting TTL and the Traffic Class Bits"> <t>The TTL and the Traffic Class bits <xref target="RFC5462"
format="default"/> in the SFL label stack entry (LSE) would
<t>The TTL and the Traffic Class bits <xref target="RFC5462"/> in the SFL label
stack entry (LSE) would
normally be set to the same value as would have been set in the label normally be set to the same value as would have been set in the label
that the SFL is synonymous with. However, it is recognized that if there that the SFL is synonymous with. However, it is recognized that, if there
is an application need these fields in the SFL Label Stack Entry (LSE) MAY be se is an application need, these fields in the SFL LSE
t these to some other value. An <bcp14>MAY</bcp14> be set to some other value. An
example would be where it was desired to cause the SFL to trigger an example would be where it was desired to cause the SFL to trigger an
action in the TTL expiry exception path as part of the label action.</t> action in the TTL expiry exception path as part of the label action.</t>
</section>
</section> </section>
</section> <section anchor="SLS" numbered="true" toc="default">
<section anchor="SLS" title="Single Label Stack"> <name>Single-Label Stack</name>
<t><xref target="Figure2" format="default"/> shows the case in which
<t><xref target="Figure2"/> shows the case in which only an LSP label is present only an LSP label is present in the
in the
MPLS label stack. Traffic with no SFL function present runs over the MPLS label stack. Traffic with no SFL function present runs over the
“normal” stack and SFL-enabled flows run over the SFL stack with the "normal" stack, and SFL-enabled flows run over the SFL stack with the
SFL used to indicate the packet batch. However in this case it is SFL used to indicate the packet batch. However, in this case, it is
necessary for the ingress Label Edge Router (LER) to first push the SFL and then necessary for the ingress Label Edge Router (LER) to first push the SFL and
to push then to push the LSP label.</t>
the LSP label.</t> <figure anchor="Figure2">
<name>Use of Synonymous Labels in a Single-Label MPLS Label Stack</nam
<figure title="Use of Synonymous Labels In A Single Label MPLS Label Stack" anch e>
or="Figure2"><artwork><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
+-----------------+ +-----------------+
| LSP | | LSP |
| Label | | Label |
| (May be PHPed) | | (May be PHPed) |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
| LSP | | | <= Synonymous with | LSP | | | <= Synonymous with
| Label | | Synonymous Flow | Explicit NULL | Label | | Synonymous Flow | Explicit NULL
| (May be PHPed) | | Label | | (May be PHPed) | | Label |
+-----------------+ <= BoS +-----------------+ <= Bottom of stack +-----------------+ <= BoS +-----------------+ <= Bottom of Stack
| | | | | | | |
| Payload | | Payload | | Payload | | Payload |
| | | | | | | |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
"Normal" Label Stack Label Stack with SFL "Normal" Label Stack Label Stack with SFL
]]></artwork></figure> ]]></artwork>
</figure>
<t>At the receiving Label Switching Router (LSR) it is necessary to consider two <t>At the receiving Label Switching Router (LSR), it is necessary to
cases:</t> consider two cases:</t>
<ol spacing="normal" type="1">
<t><list style="numbers"> <li>Where the LSP label is still present</li>
<t>Where the LSP label is still present</t> <li>Where the LSP label is penultimate hop popped</li>
<t>Where the LSP label is penultimate hop popped</t> </ol>
</list></t> <t>If the LSP label is present, it is processed exactly as it would
normally be processed, and then it is popped. This reveals the SFL,
<t>If the LSP label is present, it is processed exactly as it would which, in the case of the measurements defined in <xref
normally processed and then it is popped. This reveals the SFL, which, target="RFC6374" format="default"/>, is simply counted and then
in the case of <xref target="RFC6374"/> measurements, is simply counted and then discarded. In this respect, the processing of the SFL is synonymous
discarded. In this respect the processing of the SFL is synonymous with an MPLS Explicit NULL. As the SFL is the bottom of stack, the IP
with an MPLS Explicit NULL. As the SFL is the bottom of stack, the IP packet that follows is processed as normal.</t>
packet that follows is processed as normal.</t> <t>If the LSP label is not present due to PHP action in the upstream
LSR, two almost equivalent processing actions can take place.
<t>If the LSP label is not present due to PHP action in the upstream The SFL can be treated either 1) as an LSP label that was not PHPed and the
LSR, two almost equivalent processing actions can take place. Either
the SFL can be treated as an LSP label that was not PHPed and the
additional associated SFL action is taken when the label is additional associated SFL action is taken when the label is
processed. Alternatively, it can be treated as an MPLS Explicit NULL with processed or 2) as an MPLS Explicit NULL with
associated SFL actions. From the perspective of the measurement associated SFL actions. From the perspective of the measurement
system described in this document the behaviour of the two approaches is system described in this document, the behavior of the two approaches is
indistinguishable and thus either may be implemented.</t> indistinguishable; thus, either may be implemented.</t>
<section anchor="setting-ttl-and-the-traffic-class-bits" numbered="true"
<section anchor="setting-ttl-and-the-traffic-class-bits" title="Setting TTL and toc="default">
the Traffic Class Bits"> <name>Setting TTL and the Traffic Class Bits</name>
<t>The TTL and the Traffic Class considerations described in <xref
<t>The TTL and the Traffic Class considerations described in target="TTLandTC" format="default"/> apply.</t>
<xref target="TTLandTC"/> apply.</t> </section>
</section>
</section> <section anchor="aggregation-of-sfl-actions" numbered="true" toc="default"
</section> >
<section anchor="aggregation-of-sfl-actions" title="Aggregation of SFL Actions"> <name>Aggregation of SFL Actions</name>
<t>There are cases where it is desirable to aggregate an SFL action
<t>There are cases where it is desirable to aggregate an SFL action against a number of labels, for example, where it is desirable to
against a number of labels. For example, where it is desirable to
have one counter record the number of packets received over a group have one counter record the number of packets received over a group
of application labels, or where the number of labels used by a single of application labels or where the number of labels used by a single
application is large, and the resultant increase in the number of application is large and the resultant increase in the number of
allocated labels needed to support the SFL actions may allocated labels needed to support the SFL actions may
becomes too large to be viable. In these circumstances it would be become too large to be viable. In these circumstances, it would be
necessary to introduce an additional label in the stack to act as an necessary to introduce an additional label in the stack to act as an
aggregate instruction. This is not strictly a synonymous action in aggregate instruction. This is not strictly a synonymous action in
that the SFL is not replacing an existing label, but is somewhat that the SFL is not replacing an existing label but is somewhat
similar to the single label case shown in <xref target="SLS"/>, and the same similar to the single-label case shown in <xref target="SLS" format="default"/>,
signalling, management and configuration tools would be applicable.</t> and the same
signaling, management, and configuration tools would be applicable.</t>
<figure title="Aggregate SFL Actions" anchor="Figure3"><artwork><![CDATA[ <figure anchor="Figure3">
<name>Aggregate SFL Actions</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
+-----------------+ +-----------------+
| LSP | | LSP |
| Label | | Label |
| (May be PHPed) | | (May be PHPed) |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
| LSP | | | | LSP | | |
| Label | | Aggregate | | Label | | Aggregate |
| (May be PHPed) | | SFL | | (May be PHPed) | | SFL |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
| | | | | | | |
| Application | | Application | | Application | | Application |
| Label | | Label | | Label | | Label |
+-----------------+ <=BoS +-----------------+ <= Bottom of stack +-----------------+ <=BoS +-----------------+ <= Bottom of Stack
| | | | | | | |
| Payload | | Payload | | Payload | | Payload |
| | | | | | | |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
"Normal" Label Stack Label Stack with SFL "Normal" Label Stack Label Stack with SFL
]]></artwork></figure> ]]></artwork>
</figure>
<t>The Aggregate SFL is shown in the label stack depicted in <xref target="Figur <t>The aggregate SFL is shown in the label stack depicted in <xref
e3"/> as target="Figure3" format="default"/> as
preceding the application label, however the choice of position preceding the application label; however, the choice of position
before, or after, the application label will be application specific. before or after the application label will be application specific.
In the case described in <xref target="ALP"/>, by definition the SFL has the In the case described in <xref target="ALP" format="default"/>, by definition, t
full application context. In this case the positioning will depend he SFL has the
full application context. In this case, the positioning will depend
on whether the SFL action needs the full context of the application on whether the SFL action needs the full context of the application
to perform its action and whether the complexity of the application to perform its action and whether the complexity of the application
will be increased by finding an SFL following the application label.</t> will be increased by finding an SFL following the application label.</t>
</section>
</section> </section>
</section> <section anchor="equal-cost-multipath-considerations" numbered="true" toc="d
<section anchor="equal-cost-multipath-considerations" title="Equal Cost Multipat efault">
h Considerations"> <name>Equal-Cost Multipath Considerations</name>
<t>The introduction of an SFL to an existing flow may cause that flow to t
<t>The introduction of an SFL to an existing flow may cause that flow to take ake
a different path through the network under conditions of Equal Cost a different path through the network under conditions of Equal-Cost
Multi-path (ECMP). This in turn may invalidate certain uses of Multipath (ECMP). This, in turn, may invalidate certain uses of
the SFL such as performance measurement applications. Where this is the SFL, such as performance measurement applications. Where this is
a problem there are two solutions worthy of consideration:</t> a problem, there are two solutions worthy of consideration:</t>
<ol spacing="normal" type="1">
<t><list style="numbers"> <li>The operator <bcp14>MAY</bcp14> elect to always run with the SFL
<t>The operator MAY elect to always run with the SFL in place in the in place in the MPLS label stack.</li>
MPLS label stack.</t> <li>The operator can elect to use entropy labels <xref target="RFC6790"
<t>The operator can elect to use <xref target="RFC6790"/> Entropy Labels in format="default"/> in a network that fully supports
a network that fully supports this type of ECMP. If this this type of ECMP. If this approach is adopted, the intervening MPLS
approach is adopted, the intervening MPLS network MUST NOT network <bcp14>MUST NOT</bcp14> load balance on any packet field other
load balance on any packet field other than the entropy label. than the entropy label. Note that this is stricter than the text in
Note that this is stricter than the text in Section 4.3 of <xref target="RFC6790" sectionFormat="of" section="4.3"/>.</li>
<xref target="RFC6790"/>.</t> </ol>
</list></t> </section>
<section anchor="privacy" numbered="true" toc="default">
</section> <name>Privacy Considerations</name>
<section anchor="privacy" title="Privacy Considerations"> <t>IETF concerns on pervasive monitoring are described in <xref
target="RFC7258" format="default"/>. The inclusion of originating
<t>IETF concerns on pervasive monitoring are described in and/or flow information in a packet provides more identity information
<xref target="RFC7258"/>. The inclusion of originating and/or flow information and hence potentially degrades the privacy of the communication to an
in a attacker in a position to observe the added identifier. Whilst the
packet provides more identity information and hence potentially inclusion of the additional granularity does allow greater insight into
degrades the privacy of the communication to an attacker in a position the flow characteristics, it does not specifically identify which node
to observe the added identifier. Whilst the inclusion of originated the packet unless the attacker can inspect the network at the
the additional granularity does allow greater insight into the flow point of ingress or inspect the control protocol packets. This privacy
characteristics it does not specifically identify which node threat may be mitigated by encrypting the control protocol packets by
originated the packet unless the attacker can inspect the network at the regularly changing the synonymous labels or by concurrently using a
point of ingress, or inspection of the control protocol packets. number of such labels, including the use of a combination of those
This privacy threat may be mitigated by encrypting the control methods. Minimizing the scope of the identity indication can be useful
protocol packets, by regularly changing the synonymous labels or by in minimizing the observability of the flow characteristics. Whenever
concurrently using a number of such labels, including the use of a combination o IPFIX or other deep packet inspection (DPI) technique is used, their
f those methods. Minimizing the scope relevant privacy considerations apply.</t>
of the identity indication can be useful in minimizing the </section>
observability of the flow characteristics. Whenever IPFIX or other <section anchor="security-considerations" numbered="true" toc="default">
DPI technique is used, their relavent privacy considerations apply.</t> <name>Security Considerations</name>
<t>There are
</section>
<section anchor="security-considerations" title="Security Considerations">
<t>There are
no new security issues associated with the MPLS data plane. Any no new security issues associated with the MPLS data plane. Any
control protocol used to request SFLs will need to ensure the control protocol used to request SFLs will need to ensure the
legitimacy of the request, i.e. that the requesting node is authorized legitimacy of the request, i.e., that the requesting node is authorized
to make that SFL request by the network operator.</t> to make that SFL request by the network operator.</t>
</section>
</section> <section anchor="iana-considerations" numbered="true" toc="default">
<section anchor="iana-considerations" title="IANA Considerations"> <name>IANA Considerations</name>
<t>This document has no IANA actions.</t>
<t>This draft makes no IANA requests.</t> </section>
</section>
<section anchor="contributing-authors" title="Contributing Authors">
<figure><artwork><![CDATA[
Zhenbin Li
Huawei
Email: lizhenbin@huawei.com
]]></artwork></figure>
</section>
</middle> </middle>
<back> <back>
<references title='Normative References'> <displayreference target="I-D.bryant-mpls-sfl-control" to="MPLS-SFL-CONTROL"/>
<reference anchor="RFC5462" target='https://www.rfc-editor.org/info/rfc5462'>
<front>
<title>Multiprotocol Label Switching (MPLS) Label Stack Entry: &quot;EXP&quot; F
ield Renamed to &quot;Traffic Class&quot; Field</title>
<author initials='L.' surname='Andersson' fullname='L. Andersson'><organization
/></author>
<author initials='R.' surname='Asati' fullname='R. Asati'><organization /></auth
or>
<date year='2009' month='February' />
<abstract><t>The early Multiprotocol Label Switching (MPLS) documents defined th
e form of the MPLS label stack entry. This includes a three-bit field called th
e &quot;EXP field&quot;. The exact use of this field was not defined by these d
ocuments, except to state that it was to be &quot;reserved for experimental use&
quot;.</t><t>Although the intended use of the EXP field was as a &quot;Class of
Service&quot; (CoS) field, it was not named a CoS field by these early documents
because the use of such a CoS field was not considered to be sufficiently defin
ed. Today a number of standards documents define its usage as a CoS field.</t><
t>To avoid misunderstanding about how this field may be used, it has become incr
easingly necessary to rename this field. This document changes the name of the
field to the &quot;Traffic Class field&quot; (&quot;TC field&quot;). In doing s
o, it also updates documents that define the current use of the EXP field. [STA
NDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='5462'/>
<seriesInfo name='DOI' value='10.17487/RFC5462'/>
</reference>
<reference anchor="RFC2119" target='https://www.rfc-editor.org/info/rfc2119'>
<front>
<title>Key words for use in RFCs to Indicate Requirement Levels</title>
<author initials='S.' surname='Bradner' fullname='S. Bradner'><organization /></
author>
<date year='1997' month='March' />
<abstract><t>In many standards track documents several words are used to signify
the requirements in the specification. These words are often capitalized. This
document defines these words as they should be interpreted in IETF documents.
This document specifies an Internet Best Current Practices for the Internet Comm
unity, and requests discussion and suggestions for improvements.</t></abstract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='2119'/>
<seriesInfo name='DOI' value='10.17487/RFC2119'/>
</reference>
<reference anchor="RFC8174" target='https://www.rfc-editor.org/info/rfc8174'>
<front>
<title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title>
<author initials='B.' surname='Leiba' fullname='B. Leiba'><organization /></auth
or>
<date year='2017' month='May' />
<abstract><t>RFC 2119 specifies common key words that may be used in protocol s
pecifications. This document aims to reduce the ambiguity by clarifying that on
ly UPPERCASE usage of the key words have the defined special meanings.</t></abs
tract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='8174'/>
<seriesInfo name='DOI' value='10.17487/RFC8174'/>
</reference>
<reference anchor="RFC3032" target='https://www.rfc-editor.org/info/rfc3032'>
<front>
<title>MPLS Label Stack Encoding</title>
<author initials='E.' surname='Rosen' fullname='E. Rosen'><organization /></auth
or>
<author initials='D.' surname='Tappan' fullname='D. Tappan'><organization /></au
thor>
<author initials='G.' surname='Fedorkow' fullname='G. Fedorkow'><organization />
</author>
<author initials='Y.' surname='Rekhter' fullname='Y. Rekhter'><organization /></
author>
<author initials='D.' surname='Farinacci' fullname='D. Farinacci'><organization
/></author>
<author initials='T.' surname='Li' fullname='T. Li'><organization /></author>
<author initials='A.' surname='Conta' fullname='A. Conta'><organization /></auth
or>
<date year='2001' month='January' />
<abstract><t>This document specifies the encoding to be used by an LSR in order
to transmit labeled packets on Point-to-Point Protocol (PPP) data links, on LAN
data links, and possibly on other data links as well. This document also specif
ies rules and procedures for processing the various fields of the label stack en
coding. [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='3032'/>
<seriesInfo name='DOI' value='10.17487/RFC3032'/>
</reference>
<reference anchor="RFC6790" target='https://www.rfc-editor.org/info/rfc6790'>
<front>
<title>The Use of Entropy Labels in MPLS Forwarding</title>
<author initials='K.' surname='Kompella' fullname='K. Kompella'><organization />
</author>
<author initials='J.' surname='Drake' fullname='J. Drake'><organization /></auth
or>
<author initials='S.' surname='Amante' fullname='S. Amante'><organization /></au
thor>
<author initials='W.' surname='Henderickx' fullname='W. Henderickx'><organizatio
n /></author>
<author initials='L.' surname='Yong' fullname='L. Yong'><organization /></author
>
<date year='2012' month='November' />
<abstract><t>Load balancing is a powerful tool for engineering traffic across a
network. This memo suggests ways of improving load balancing across MPLS networ
ks using the concept of &quot;entropy labels&quot;. It defines the concept, des
cribes why entropy labels are useful, enumerates properties of entropy labels th
at allow maximal benefit, and shows how they can be signaled and used for variou
s applications. This document updates RFCs 3031, 3107, 3209, and 5036. [STANDA
RDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='6790'/>
<seriesInfo name='DOI' value='10.17487/RFC6790'/>
</reference>
</references>
<references title='Informative References'>
<reference anchor="RFC3985" target='https://www.rfc-editor.org/info/rfc3985'>
<front>
<title>Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture</title>
<author initials='S.' surname='Bryant' fullname='S. Bryant' role='editor'><organ
ization /></author>
<author initials='P.' surname='Pate' fullname='P. Pate' role='editor'><organizat
ion /></author>
<date year='2005' month='March' />
<abstract><t>This document describes an architecture for Pseudo Wire Emulation E
dge-to-Edge (PWE3). It discusses the emulation of services such as Frame Relay,
ATM, Ethernet, TDM, and SONET/SDH over packet switched networks (PSNs) using IP
or MPLS. It presents the architectural framework for pseudo wires (PWs), defin
es terminology, and specifies the various protocol elements and their functions.
This memo provides information for the Internet community.</t></abstract>
</front>
<seriesInfo name='RFC' value='3985'/>
<seriesInfo name='DOI' value='10.17487/RFC3985'/>
</reference>
<reference anchor="RFC8372" target='https://www.rfc-editor.org/info/rfc8372'>
<front>
<title>MPLS Flow Identification Considerations</title>
<author initials='S.' surname='Bryant' fullname='S. Bryant'><organization /></au
thor>
<author initials='C.' surname='Pignataro' fullname='C. Pignataro'><organization
/></author>
<author initials='M.' surname='Chen' fullname='M. Chen'><organization /></author
>
<author initials='Z.' surname='Li' fullname='Z. Li'><organization /></author>
<author initials='G.' surname='Mirsky' fullname='G. Mirsky'><organization /></au
thor>
<date year='2018' month='May' />
<abstract><t>This document discusses aspects to consider when developing a solut
ion for MPLS flow identification. The key application that needs this solution
is in-band performance monitoring of MPLS flows when MPLS is used to encapsulate
user data packets.</t></abstract>
</front>
<seriesInfo name='RFC' value='8372'/>
<seriesInfo name='DOI' value='10.17487/RFC8372'/>
</reference>
<reference anchor="RFC6374" target='https://www.rfc-editor.org/info/rfc6374'>
<front>
<title>Packet Loss and Delay Measurement for MPLS Networks</title>
<author initials='D.' surname='Frost' fullname='D. Frost'><organization /></auth
or>
<author initials='S.' surname='Bryant' fullname='S. Bryant'><organization /></au
thor>
<date year='2011' month='September' />
<abstract><t>Many service provider service level agreements (SLAs) depend on the
ability to measure and monitor performance metrics for packet loss and one-way
and two-way delay, as well as related metrics such as delay variation and channe
l throughput. This measurement capability also provides operators with greater
visibility into the performance characteristics of their networks, thereby facil
itating planning, troubleshooting, and network performance evaluation. This doc
ument specifies protocol mechanisms to enable the efficient and accurate measure
ment of these performance metrics in MPLS networks. [STANDARDS-TRACK]</t></abst
ract>
</front>
<seriesInfo name='RFC' value='6374'/>
<seriesInfo name='DOI' value='10.17487/RFC6374'/>
</reference>
<reference anchor="RFC7258" target='https://www.rfc-editor.org/info/rfc7258'>
<front>
<title>Pervasive Monitoring Is an Attack</title>
<author initials='S.' surname='Farrell' fullname='S. Farrell'><organization /></
author>
<author initials='H.' surname='Tschofenig' fullname='H. Tschofenig'><organizatio
n /></author>
<date year='2014' month='May' />
<abstract><t>Pervasive monitoring is a technical attack that should be mitigated
in the design of IETF protocols, where possible.</t></abstract>
</front>
<seriesInfo name='BCP' value='188'/>
<seriesInfo name='RFC' value='7258'/>
<seriesInfo name='DOI' value='10.17487/RFC7258'/>
</reference>
<reference anchor="RFC8321" target='https://www.rfc-editor.org/info/rfc8321'>
<front>
<title>Alternate-Marking Method for Passive and Hybrid Performance Monitoring</t
itle>
<author initials='G.' surname='Fioccola' fullname='G. Fioccola' role='editor'><o
rganization /></author>
<author initials='A.' surname='Capello' fullname='A. Capello'><organization /></
author>
<author initials='M.' surname='Cociglio' fullname='M. Cociglio'><organization />
</author>
<author initials='L.' surname='Castaldelli' fullname='L. Castaldelli'><organizat
ion /></author>
<author initials='M.' surname='Chen' fullname='M. Chen'><organization /></author
>
<author initials='L.' surname='Zheng' fullname='L. Zheng'><organization /></auth
or>
<author initials='G.' surname='Mirsky' fullname='G. Mirsky'><organization /></au
thor>
<author initials='T.' surname='Mizrahi' fullname='T. Mizrahi'><organization /></
author>
<date year='2018' month='January' />
<abstract><t>This document describes a method to perform packet loss, delay, and
jitter measurements on live traffic. This method is based on an Alternate-Mark
ing (coloring) technique. A report is provided in order to explain an example a
nd show the method applicability. This technology can be applied in various sit
uations, as detailed in this document, and could be considered Passive or Hybrid
depending on the application.</t></abstract>
</front>
<seriesInfo name='RFC' value='8321'/>
<seriesInfo name='DOI' value='10.17487/RFC8321'/>
</reference>
<reference anchor="RFC7011" target='https://www.rfc-editor.org/info/rfc7011'>
<front>
<title>Specification of the IP Flow Information Export (IPFIX) Protocol for the
Exchange of Flow Information</title>
<author initials='B.' surname='Claise' fullname='B. Claise' role='editor'><organ
ization /></author>
<author initials='B.' surname='Trammell' fullname='B. Trammell' role='editor'><o
rganization /></author>
<author initials='P.' surname='Aitken' fullname='P. Aitken'><organization /></au
thor>
<date year='2013' month='September' />
<abstract><t>This document specifies the IP Flow Information Export (IPFIX) prot
ocol, which serves as a means for transmitting Traffic Flow information over the
network. In order to transmit Traffic Flow information from an Exporting Proce
ss to a Collecting Process, a common representation of flow data and a standard
means of communicating them are required. This document describes how the IPFIX
Data and Template Records are carried over a number of transport protocols from
an IPFIX Exporting Process to an IPFIX Collecting Process. This document obsol
etes RFC 5101.</t></abstract>
</front>
<seriesInfo name='STD' value='77'/>
<seriesInfo name='RFC' value='7011'/>
<seriesInfo name='DOI' value='10.17487/RFC7011'/>
</reference>
<reference anchor="I-D.bryant-mpls-sfl-control">
<front>
<title>A Simple Control Protocol for MPLS SFLs</title>
<author initials='S' surname='Bryant' fullname='Stewart Bryant'>
<organization />
</author>
<author initials='G' surname='Swallow' fullname='George Swallow'>
<organization />
</author>
<author initials='S' surname='Sivabalan' fullname='Siva Sivabalan'>
<organization />
</author>
<date month='June' day='8' year='2020' />
<abstract><t>In draft-ietf-mpls-sfl-framework the concept of MPLS synonymous flo
w labels (SFL) was introduced. This document describes a simple control protoco
l that runs over an associated control header to request, withdraw, and extend t
he lifetime of such labels. It is not the only control protocol that moght be u
sed to support SFL, but it has the benefit of being able to be used without modi
fying of the existing MPLS control prodocols. The existance of this design is n
ot intended to restrict the ability to enhance an existing MPLS control protocol
to add a similar capability. A Querier MUST wait a configured time (suggested
wait of 60 seconds) before re-attempting a Withdraw request. No more than three
Withdraw requests SHOULD be made. These restricctions are to prevent overloadi
ng the control plane of the actioning router.</t></abstract>
</front>
<seriesInfo name='Internet-Draft' value='draft-bryant-mpls-sfl-control-08' /> <references>
<format type='TXT' <name>References</name>
target='http://www.ietf.org/internet-drafts/draft-bryant-mpls-sfl-contro <references>
l-08.txt' /> <name>Normative References</name>
</reference> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.5462.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.2119.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8174.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.3032.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.6790.xml"/>
</references>
<references>
<name>Informative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.3985.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8372.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.6374.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.7258.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8321.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.7011.xml"/>
<xi:include href="https://datatracker.ietf.org/doc/bibxml3/reference.I-D
.bryant-mpls-sfl-control.xml"/>
</references>
</references> </references>
<section anchor="contributing-authors" numbered="false" toc="default">
<name>Contributors</name>
<contact fullname="Zhenbin Li">
<organization>Huawei</organization>
<address>
<postal/>
<email>lizhenbin@huawei.com</email>
</address>
</contact>
</section>
</back> </back>
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