Hi Authors, WG, Thanks for this spec. I can see the need to clear up this ambiguity.
I’ve supplied most of my questions and comments in the form of an edited copy
of the draft. Minor editorial suggestions I’ve made in place without further
comment, most of my more substantive questions and comments are done in-line
and prefixed with “jgs:”. You can use your favorite diff tool to review them;
I’ve attached the iddiff output for your convenience if you’d like to use it.
I’ve also pasted a traditional diff below in case you want to use it for
in-line reply.
In addition to my various inline comments, I have a general question/comment.
The spec, as far as I can tell, is technology-agnostic: it introduces the E
flag and codifies the interpretation of the E+L flags. It doesn’t restrict this
to any particular data plane. That seems like the right choice. But, the draft
also opens with several paragraphs of discussion of Segment Routing in the
Introduction, and its normative language is SR-specific (search for “SID” in
the document to see what I mean, SIDs are an SR construct).
Is the applicability of the document intended to be specific to Segment
Routing? If so I think this needs to be made clearer. Or, if the document is
NOT intended to be restricted to SR, then revisions are needed everywhere after
the Introduction where the string ‘SID’ occurs, to make it technology-agnostic.
(Less importantly, one might also ask why the Introduction needs to contain a
tutorial on SR.)
Thanks,
—John
--- draft-ietf-pce-local-protection-enforcement-08.txt 2023-04-20
14:28:28.000000000 -0400
+++ draft-ietf-pce-local-protection-enforcement-08-jgs-comments.txt
2023-04-20 15:25:51.000000000 -0400
@@ -148,15 +148,21 @@
calculated to include other segment identifiers which are not
applicable to having their protection state advertised, as they may
only be locally significant for each router processing the SID, such
- as Node SIDs, it may not be possible for PCE to include the
+ as Node SIDs, it may not be possible for the PCE to include the
protection constraint as part of the path calculation.
- It is desirable for an operator to define the enforcement, or
+ It is desirable for an operator to be able to define the enforcement, or
strictness of the protection requirement when it can be applied.
+---
+jgs: I don't follow what you mean by "... or strictness of the protection
+requirement when it can be applied." I'm getting hung up on the "when it
+can be applied" part. Would it be correct to just delete those words? Or
+if it wouldn't, can you help me understand what work they're doing? Thanks.
+---
This document updates [RFC5440] by further describing the behaviour
- with Local Protection Desired Flag (L flag) and extends on it with
- the introduction of Enforcement Flag (E flag).
+ with the Local Protection Desired Flag (L flag) and extends on it with
+ the introduction of the Enforcement Flag (E flag).
@@ -286,6 +292,25 @@
the PCE a preference on which SID to select, as the behaviour of the
LSP would differ during a local failure depending on which SID is
selected.
+---
+jgs: I thought this paragraph was going to answer a question I have,
+when it began with "... cases where there is simply no requirement to
+enforce protection or no protection ..." That is, sometimes the
+operator may simply _not care_ at all, they just want (for example)
+the lowest-latency path.
+
+But then my hopes were dashed, because at the end of the paragraph
+you segue (without explaining why) into "... give the PCE a preference".
+But isn't the case you introduced, the one where there literally is no
+preference?
+
+As this is written, it seems as though there is missing support for the
+true "don't care" case. If this was discussed in the WG and the consensus
+was that, er, the WG doesn't care about the "don't care" case, I'd like
+to know that. If I'm confused and somehow "don't care" is properly
+captured by one (both?!?) of these options, I'd like to know that, and
+understand how. If I'm terribly confused, I'd like to know that, too. :-)
+---
5. Protection Enforcement Flag (E flag)
@@ -359,6 +384,16 @@
consider the protection eligibility as an UNPROTECTED PREFERRED
constraint but MAY consider protection eligibility as an UNPROTECTED
MANDATORY constraint.
+---
+jgs: It's not self-evident why this SHOULD/MAY is written this way. The
+obvious choice would have been to make the SHOULD a MUST and omit the
+MAY -- indeed, if 'enforcement' is set to false, it's hard to see a
+justification for making enforcement mandatory! So it seems as though
+there must be some backstory here. Can you help me understand? (Or
+better yet, make the SHOULD a MUST...)
+
+See also my comment just below.
+---
When L flag is set to 0 and E flag is set to 1, then the PCE MUST
consider the protection eligibility as an UNPROTECTED MANDATORY
@@ -368,10 +403,27 @@
they indicate the preference of selection of a SID if PCE has an
option of either protected or unprotected available on a link. The
definition of UNPROTECTED PREFERRED is primarily as a guidance on how
- PCE should behave when L bit is not set, maintaining compatibility
+ PCE should behave when the L bit is not set, maintaining compatibility
with existing known implementations prior to this document. When
presented with either option, PCE SHOULD select the SID which has a
protection state matching the state of the L flag.
+---
+jgs: I'm afraid I had a hard time making sense of this paragraph. :-( I
+think maybe it's mashing together a couple different and only
+loosely-related thoughts?
+
+One of them is (perhaps?) the answer to my question above, and in effect
+is saying "some implementations do one thing and some do another and we
+didn't want to make any of them noncompliant so we threw in a MAY",
+which I'm not sure is a strong enough reason (we can discuss further).
+
+The final sentence seems like it doesn't belong, and in fact it seems
+like it should be removed. As far as I can tell it's redundant with the
+two "... and the E flag ... set to 0" paragraphs above. It also subtly
+conflicts with the first of those paragraphs. It's better to specify
+things just once, for this reason -- I suggest you remove the final
+sentence.
+---
The protection enforcement constraint can only be applied to resource
selection in which the protection state or eligibility for protection
@@ -394,7 +446,7 @@
Internet-Draft Protection Enforcement November 2022
-5.1. Backwards Compatibility
+5.1. Backward Compatibility
Considerations in the message passing between the PCC and the PCE for
the E flag bit which are not supported by the entity are outlined in
@@ -419,18 +471,33 @@
the E flag set to 0 for PCE-initiated LSPs even if set to 1 in the
prior PCInitiate or PCUpd.
- For a PCC which does support this document, it MAY set E flag to 1
+ For a PCC which does support this document, it MAY set the E flag to 1
depending on local configuration. If communicating with a PCE which
does not yet support this document, the PCE follows the behaviour
specified in [RFC5440] and will ignore the E flag. Thus, it will not
compute a path respecting the enforcement constraint.
+---
+jgs: It *will* not compute a path respecting the constraint? Or it
+*might* not? All the introductory material, about the ambiguity of
+how implementations handle the L flag, makes me think it *might*
+not, or alternately, it cannot be guaranteed to respect the
+constraint. As you've written it, it says that is guaranteed not to
+respect the constraint, which I think is probably wrong.
+---
For PCC-initiated LSPs, the PCC SHOULD ignore the E flag value
received from the PCE in a PCUpd message.
+---
+jgs: What would it mean for the PCC not to ignore the E flag? Is there
+any reason for this to be SHOULD and not MUST?
+---
For PCE-initiated LSPs, the PCC MAY process the E flag value received
- from the PCE in a PCUpd message. PCE SHOULD ignore the E flag value
+ from the PCE in a PCUpd message. The PCE SHOULD ignore the E flag value
received from the PCC in a PCRpt message.
+---
+jgs: same question about this SHOULD.
+---
6. Implementation Status
Network Working Group A. Stone
Internet-Draft M. Aissaoui
Updates: 5440 (if approved) Nokia
Intended status: Standards Track S. Sidor
Expires: 21 May 2023 Cisco Systems, Inc.
S. Sivabalan
Ciena Coroporation
17 November 2022
Local Protection Enforcement in PCEP
draft-ietf-pce-local-protection-enforcement-08
Abstract
This document extends the base specification to clarify usage of the
local protection desired bit signalled in the Path Computation
Element Protocol (PCEP). This document also introduces a new flag
for signalling protection strictness in PCEP.
Status of This Memo
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 https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 21 May 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Implementation differences . . . . . . . . . . . . . . . 4
4.2. SLA Enforcement . . . . . . . . . . . . . . . . . . . . . 5
5. Protection Enforcement Flag (E flag) . . . . . . . . . . . . 6
5.1. Backwards Compatibility . . . . . . . . . . . . . . . . . 8
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 8
6.1. Nokia Implementation . . . . . . . . . . . . . . . . . . 9
6.2. Cisco Implementation . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . 11
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
The Path Computation Element (PCE) Communication Protocol (PCEP)
[RFC5440] enables the communication between a Path Computation Client
(PCC) and a PCE, or between two PCEs based on the PCE architecture
[RFC4655].
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PCEP [RFC5440] utilizes flags, values and concepts previously defined
in RSVP-TE Extensions [RFC3209] and Fast Reroute Extensions to RSVP-
TE [RFC4090]. One such concept in PCEP is the 'Local Protection
Desired' (L flag in the LSPA Object in [RFC5440]), which was
originally defined in the SESSION-ATTRIBUTE Object in RFC3209. In
RSVP, this flag signals to downstream routers that that they may use
a local repair mechanism. The headend router calculating the path
does not know whether a downstream router will or will not protect a
hop during its calculation. Therefore, a local protection desired
does not require the transit router to satisfy protection in order to
establish the RSVP signalled path. This flag is signalled in PCEP as
an attribute of the LSP via the LSP Attributes object.
PCEP Extensions for Segment Routing ([RFC8664]) extends support in
PCEP for Segment Routed LSPs (SR-LSPs) as defined in the Segment
Routing Architecture [RFC8402]. As per the Segment Routing
Architecture, Adjacency Segment Identifiers(Adj-SID) may be eligible
for protection (using IPFRR or MPLS-FRR). The protection eligibility
is advertised into the IGP ([RFC8665] and [RFC8667]) as the B-Flag
part of the Adjacency SID sub-tlv and can be discovered by a PCE via
BGP-LS [RFC7752] using the BGP-LS Segment Routing Extensions
([RFC9085]). An Adjacency SID may or may not have protection
eligibility and, for a given adjacency between two routers, there may
be multiple Adjacency SIDs, some of which are protected and some
which are not.
A Segment Routed path calculated by a PCE may contain various types
of segments, as defined in [RFC8402] such as Adjacency, Node or
Binding. The protection eligibility for Adjacency SIDs can be
discovered by the PCE, therefore the PCE can take the protection
eligibility into consideration as a path constraint. If a path is
calculated to include other segment identifiers which are not
applicable to having their protection state advertised, as they may
only be locally significant for each router processing the SID, such
as Node SIDs, it may not be possible for the PCE to include the
protection constraint as part of the path calculation.
It is desirable for an operator to be able to define the enforcement, or
strictness of the protection requirement when it can be applied.
---
jgs: I don't follow what you mean by "... or strictness of the protection
requirement when it can be applied." I'm getting hung up on the "when it
can be applied" part. Would it be correct to just delete those words? Or
if it wouldn't, can you help me understand what work they're doing? Thanks.
---
This document updates [RFC5440] by further describing the behaviour
with the Local Protection Desired Flag (L flag) and extends on it with
the introduction of the Enforcement Flag (E flag).
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2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Terminology
This document uses the following terminology:
PROTECTION MANDATORY: The Path MUST have protection eligibility on
all links.
UNPROTECTED MANDATORY: The Path MUST NOT have protection eligibility
on all links.
PROTECTION PREFERRED: The Path SHOULD have protection eligibility on
all links but MAY contain links which do not have protection
eligibility.
UNPROTECTED PREFERRED: The Path SHOULD NOT have protection
eligibility on all links but MAY contain links which have protection
eligibility.
PCC: Path Computation Client. Any client application requesting a
path computation to be performed by a Path Computation Element.
PCE: Path Computation Element. An entity (component, application, or
network node) that is capable of computing a network path or route
based on a network graph and applying computational constraints.
PCEP: Path Computation Element Protocol.
LSPA: LSP Attributes Object in PCEP, defined in RFC5440
4. Motivation
4.1. Implementation differences
As defined in [RFC5440] the mechanism to signal protection
enforcement in PCEP is the previously mentioned L flag defined in the
LSPA Object. The name of the flag uses the term "Desired", which by
definition means "strongly wished for or intended" and the use case
originated from the RSVP. For RSVP signalled paths, local protection
is not within control of the PCE. However, [RFC5440] does state
"When set, this means that the computed path must include links
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protected with Fast Reroute as defined in [RFC4090]."
Implementations of [RFC5440] have either interpreted the L flag as
PROTECTION MANDATORY or PROTECTION PREFERRED, leading to operational
differences.
4.2. SLA Enforcement
The boolean bit L flag is unable to distinguish between the different
options of PROTECTION MANDATORY, UNPROTECTED MANDATORY, PROTECTION
PREFERRED and UNPROTECTED PREFERRED. Selecting one of the options is
typically dependent on the service level agreement the operator
wishes to impose on the LSP. A network may be providing transit to
multiple service agreement definitions against the same base topology
network, whose behavior could vary, such as wanting local protection
to be invoked on some LSPs and not wanting local protection on
others. When enforcement is used, the resulting shortest path
calculation is impacted.
For example, PROTECTION MANDATORY is for use cases where an operator
may need the LSP to follow a path which has local protection provided
along the full path, ensuring that if there is a failure anywhere
along the path that traffic will be fast re-routed at the point.
For example, UNPROTECTED MANDATORY is when an operator may
intentionally prefer an LSP to not be locally protected, and thus
would rather local failures cause the LSP to go down. An example
scenario is one where an LSP is protected with path protection via a
secondary diverse LSP. Each LSP is traffic engineered to follow
specific traffic engineered criteria computed by the PCE to satisfy
SLA. Upon a failure, if local protection is invoked on the active
LSP traffic, the traffic may temporarily traverse links which violate
the TE requirements and could negatively impact the resources being
traversed (e.g., insufficient bandwidth). In addition, depending on
the network topological scenario, it may be not feasible for the PCE
to reroute the LSP while respecting the TE requirements which include
path diversity, resulting in the LSP being torn down and switched to
the protected path anyways. In such scenarios its desirable for the
LSP to be simply torn down immediately and not re-routed through
local protection, so that traffic may be forwarded through an already
established traffic-engineered secondary path.
There are also use cases where there is simply no requirement to
enforce protection or no protection along a path. This can be
considered as "do not care to enforce". This is a relaxation of the
protection constraint. The path calculation is permitted the use of
any SID which is available along the calculated path. The SID backup
availability does not impact the shortest path computation. Since
links may have both protected and unprotected SIDs available, the
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option PROTECTION PREFERRED or UNPROTECTED PREFERRED is used to give
the PCE a preference on which SID to select, as the behaviour of the
LSP would differ during a local failure depending on which SID is
selected.
---
jgs: I thought this paragraph was going to answer a question I have,
when it began with "... cases where there is simply no requirement to
enforce protection or no protection ..." That is, sometimes the
operator may simply _not care_ at all, they just want (for example)
the lowest-latency path.
But then my hopes were dashed, because at the end of the paragraph
you segue (without explaining why) into "... give the PCE a preference".
But isn't the case you introduced, the one where there literally is no
preference?
As this is written, it seems as though there is missing support for the
true "don't care" case. If this was discussed in the WG and the consensus
was that, er, the WG doesn't care about the "don't care" case, I'd like
to know that. If I'm confused and somehow "don't care" is properly
captured by one (both?!?) of these options, I'd like to know that, and
understand how. If I'm terribly confused, I'd like to know that, too. :-)
---
5. Protection Enforcement Flag (E flag)
Section 7.11 in Path Computation Element Protocol [RFC5440] describes
the encoding of the Local Protection Desired (L flag). A Protection
Enforcement flag "E" is specified below, extending the L flag.
[RFC Editor Note: The text below assumes the E bit remains the early
allocation value 6. Please adjust if this changes and remove this
note before publication.]
Codespace of the Flag field (LSPA Object)
Bit Description Reference
7 Local Protection Desired RFC5440
6 Local Protection Enforcement This document
The format of the LSPA Object as defined in [RFC5440] is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Exclude-any |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Include-any |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Include-all |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Setup Prio | Holding Prio | Flags |E|L| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Optional TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Flags (8 bits)
* L Flag: As defined in [RFC5440] and further updated by this
document. When set to 1, protection is desired. When set to 0,
protection is not desired. The enforcement of the protection is
identified via the E flag.
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* E Flag (Protection Enforcement): This flag controls the strictness
in which the PCE must apply the L flag. When set to 1, the value
of the L flag MUST be respected during SID selection by the PCE.
When E flag is set to 0, the value of the L flag SHOULD be
respected as selection criteria; however, the PCE is permitted to
relax or ignore the L flag when computing a path. The statements
below indicate preference when E flag is set to 0 in combination
with the L flag value.
When both the L flag and E flag are set to 1, then the PCE MUST
consider the protection eligibility as a PROTECTION MANDATORY
constraint.
When the L flag is set to 1 and the E flag is set to 0, then the PCE
MUST consider the protection eligibility as a PROTECTION PREFERRED
constraint.
When both L flag and E flag are set to 0, then the PCE SHOULD
consider the protection eligibility as an UNPROTECTED PREFERRED
constraint but MAY consider protection eligibility as an UNPROTECTED
MANDATORY constraint.
---
jgs: It's not self-evident why this SHOULD/MAY is written this way. The
obvious choice would have been to make the SHOULD a MUST and omit the
MAY -- indeed, if 'enforcement' is set to false, it's hard to see a
justification for making enforcement mandatory! So it seems as though
there must be some backstory here. Can you help me understand? (Or
better yet, make the SHOULD a MUST...)
See also my comment just below.
---
When L flag is set to 0 and E flag is set to 1, then the PCE MUST
consider the protection eligibility as an UNPROTECTED MANDATORY
constraint.
UNPROTECTED PREFERRED and PROTECTED PREFERRED may seem similar but
they indicate the preference of selection of a SID if PCE has an
option of either protected or unprotected available on a link. The
definition of UNPROTECTED PREFERRED is primarily as a guidance on how
PCE should behave when the L bit is not set, maintaining compatibility
with existing known implementations prior to this document. When
presented with either option, PCE SHOULD select the SID which has a
protection state matching the state of the L flag.
---
jgs: I'm afraid I had a hard time making sense of this paragraph. :-( I
think maybe it's mashing together a couple different and only
loosely-related thoughts?
One of them is (perhaps?) the answer to my question above, and in effect
is saying "some implementations do one thing and some do another and we
didn't want to make any of them noncompliant so we threw in a MAY",
which I'm not sure is a strong enough reason (we can discuss further).
The final sentence seems like it doesn't belong, and in fact it seems
like it should be removed. As far as I can tell it's redundant with the
two "... and the E flag ... set to 0" paragraphs above. It also subtly
conflicts with the first of those paragraphs. It's better to specify
things just once, for this reason -- I suggest you remove the final
sentence.
---
The protection enforcement constraint can only be applied to resource
selection in which the protection state or eligibility for protection
is known to PCE. It is RECOMMENDED that a PCE assume a Node SID is
protected. It is RECOMMENDED for a PCE to assume an Adjacency SID is
protected if the backup flag advertised with the Adjacency SID is
set. If a PCE is unable to infer protection status of a resource,
PCE MAY use local policy to define protected status assumptions.
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5.1. Backward Compatibility
Considerations in the message passing between the PCC and the PCE for
the E flag bit which are not supported by the entity are outlined in
this section, with requirements for the PCE and the PCC implementing
this document described at the end.
For a PCC or PCE which does not yet support this document, the E flag
is ignored and set to zero in PCRpt and/or PCUpd as per [RFC5440] for
PCC-initiated or as per [RFC8281] for PCE-initiated LSPs. It is
important to note that [RFC8231] and [RFC8281] permit the LSP
Attribute Object to be included in PCUpd messages for PCC-initiated
and PCE-initiated LSPs.
For PCC-initiated LSPs, PCUpd E flag (and L flag) is an echo from the
previous PCRpt however the bit value is ignored on the PCE from the
previous PCRpt, therefore the E flag value set in the PCUpd is zero.
A PCE which does not support this document sends PCUpd messages with
the E flag set to 0 for PCC-initated LSPs even if set to 1 in the
prior PCReq or PCRpt.
A PCC which does not support this document sends PCRpt messages with
the E flag set to 0 for PCE-initiated LSPs even if set to 1 in the
prior PCInitiate or PCUpd.
For a PCC which does support this document, it MAY set the E flag to 1
depending on local configuration. If communicating with a PCE which
does not yet support this document, the PCE follows the behaviour
specified in [RFC5440] and will ignore the E flag. Thus, it will not
compute a path respecting the enforcement constraint.
---
jgs: It *will* not compute a path respecting the constraint? Or it
*might* not? All the introductory material, about the ambiguity of
how implementations handle the L flag, makes me think it *might*
not, or alternately, it cannot be guaranteed to respect the
constraint. As you've written it, it says that is guaranteed not to
respect the constraint, which I think is probably wrong.
---
For PCC-initiated LSPs, the PCC SHOULD ignore the E flag value
received from the PCE in a PCUpd message.
---
jgs: What would it mean for the PCC not to ignore the E flag? Is there
any reason for this to be SHOULD and not MUST?
---
For PCE-initiated LSPs, the PCC MAY process the E flag value received
from the PCE in a PCUpd message. The PCE SHOULD ignore the E flag value
received from the PCC in a PCRpt message.
---
jgs: same question about this SHOULD.
---
6. Implementation Status
[Note to the RFC Editor - remove this section before publication, as
well as remove the reference to RFC 7942.]
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
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RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalogue of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
6.1. Nokia Implementation
* Organization: Nokia
* Implementation: NSP PCE and SROS PCC.
* Description: Implementation for calculation and conveying
intention described in this document
* Maturity Level: Demo
* Coverage: Full
* Contact: [email protected]
6.2. Cisco Implementation
* Organization: Cisco Systems, Inc.
* Implementation: IOS-XR PCE and PCC.
* Description: Implementation for calculation and conveying
intention described in this document
* Maturity Level: Demo
* Coverage: Full
* Contact: [email protected]
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7. Security Considerations
This document clarifies the behaviour of an existing flag and
introduces a new flag to provide further control of that existing
behaviour. The introduction of this new flag and behaviour
clarification does not create any new sensitive information. No
additional security measure is required.
Securing the PCEP session using Transport Layer Security (TLS)
[RFC8253], as per the recommendations and best current practices in
[RFC7525] is RECOMMENDED.
8. IANA Considerations
[RFC Editor Note: The text below assumes the E bit remains the early
allocation value 6. Please adjust if this changes and remove this
note before publication.]
This document defines a new bit value in the sub-registry "LSPA
Object Flag Field" in the "Path Computation Element Protocol (PCEP)
Numbers" registry. IANA has made the following codepoint allocation.
Bit Name Reference
6 Protection Enforcement This document
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., Shakir, R., and RFC
Publisher, "Segment Routing Architecture", RFC 8402,
DOI 10.17487/RFC8402, July 2018,
<https://www.rfc-editor.org/info/rfc8402>.
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[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
Swallow, G., and RFC Publisher, "RSVP-TE: Extensions to
RSVP for LSP Tunnels", RFC 3209, DOI 10.17487/RFC3209,
December 2001, <https://www.rfc-editor.org/info/rfc3209>.
[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
DOI 10.17487/RFC4090, May 2005,
<https://www.rfc-editor.org/info/rfc4090>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A.,
Ray, S., and RFC Publisher, "North-Bound Distribution of
Link-State and Traffic Engineering (TE) Information Using
BGP", RFC 7752, DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., Dhody, D., and
RFC Publisher, "PCEPS: Usage of TLS to Provide a Secure
Transport for the Path Computation Element Communication
Protocol (PCEP)", RFC 8253, DOI 10.17487/RFC8253, October
2017, <https://www.rfc-editor.org/info/rfc8253>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., Varga, R., and RFC
Publisher, "Path Computation Element Communication
Protocol (PCEP) Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., Varga, R., and RFC
Publisher, "Path Computation Element Communication
Protocol (PCEP) Extensions for PCE-Initiated LSP Setup in
a Stateful PCE Model", RFC 8281, DOI 10.17487/RFC8281,
December 2017, <https://www.rfc-editor.org/info/rfc8281>.
[RFC7525] Sheffer, Y., Holz, R., Saint-Andre, P., and RFC Publisher,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
9.2. Informative References
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[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
Hardwick, J., and RFC Publisher, "Path Computation Element
Communication Protocol (PCEP) Extensions for Segment
Routing", RFC 8664, DOI 10.17487/RFC8664, December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
[RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", RFC 8665,
DOI 10.17487/RFC8665, December 2019,
<https://www.rfc-editor.org/info/rfc8665>.
[RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Extensions for Segment Routing", RFC 8667,
DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>.
[RFC9085] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Gredler,
H., Chen, M., and RFC Publisher, "Border Gateway Protocol
- Link State (BGP-LS) Extensions for Segment Routing",
RFC 9085, DOI 10.17487/RFC9085, August 2021,
<https://www.rfc-editor.org/info/rfc9085>.
Acknowledgements
Thanks to Dhruv Dhody and Mike Koldychev for reviewing and providing
very valuable feedback and discussions on this document.
Thanks to Julien Meuric for shepherding this document.
Authors' Addresses
Andrew Stone
Nokia
600 March Road
Kanata Ontario K2K 2T6
Canada
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Email: [email protected]
Mustapha Aissaoui
Nokia
600 March Road
Kanata Ontario K2K 2T6
Canada
Email: [email protected]
Samuel Sidor
Cisco Systems, Inc.
Eurovea Central 3.
Pribinova 10
811 09 Bratislava
Slovakia
Email: [email protected]
Siva Sivabalan
Ciena Coroporation
385 Terry Fox Drive
Kanata Ontario K2K 0L1
Canada
Email: [email protected]
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