draft-ietf-pce-iro-update-05.txt   draft-ietf-pce-iro-update-06.txt 
PCE Working Group D. Dhody PCE Working Group D. Dhody
Internet-Draft Huawei Technologies Internet-Draft Huawei Technologies
Updates: 5440 (if approved) January 27, 2016 Updates: 5440 (if approved) March 14, 2016
Intended status: Standards Track Intended status: Standards Track
Expires: July 30, 2016 Expires: September 15, 2016
Update to Include Route Object (IRO) specification in Path Computation Update to Include Route Object (IRO) specification in Path Computation
Element communication Protocol (PCEP) Element communication Protocol (PCEP)
draft-ietf-pce-iro-update-05 draft-ietf-pce-iro-update-06
Abstract Abstract
During discussions of a document to provide a standard representation The Path Computation Element Communication Protocol (PCEP) provides
and encoding of Domain-Sequence within the Path Computation Element for communications between a Path Computation Client (PCC) and a PCE,
(PCE) communication Protocol (PCEP) for communications between a Path or between two PCEs. RFC 5440 defines the Include Route Object (IRO)
Computation Client (PCC) and a PCE, or between two PCEs, it was to specify network elements to be traversed in the computed path.
determined that there was a need for clarification with respect to The specification did not specify if the IRO contains an ordered or
the ordered nature of the Include Route Object (IRO). un-ordered list of sub-objects. During recent discussions, it was
determined that there was a need to define a standard representation
to ensure interoperability.
An informal survey was conducted to determine the state of current An informal survey was conducted to determine the state of current
and planned implementation with respect to IRO ordering and handling and planned implementations with respect to IRO ordering and the
of Loose bit (L bit). handling of an attribute of the IRO's sub-object, the Loose hop bit
(L bit).
This document updates RFC 5440 regarding the IRO specification, based This document updates RFC 5440 regarding the IRO specification, based
on the survey conclusion and recommendation. on the survey conclusion and recommendation.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 30, 2016. This Internet-Draft will expire on September 15, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 50 skipping to change at page 2, line 50
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 6 7.2. Informative References . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
The Path Computation Element Communication Protocol (PCEP) provides The Path Computation Element Communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path for communications between a Path Computation Client (PCC) and a PCE,
computations in response to Path Computation Clients (PCCs) requests. or between two PCEs. [RFC5440] defines the Include Route Object
(IRO) to specify network elements to be traversed in the computed
[RFC5440] defines the Include Route Object (IRO) to specify network path. The specification did not define if the IRO is an ordered or
elements to be traversed in the computed path. The specification did un-ordered list of sub-objects. In addition, it defined the Loose
not mention if IRO is an ordered or un-ordered list of sub-objects. hop bit (L bit) to have no meaning within an IRO.
It mentioned that the Loose bit (L bit) has no meaning within an IRO.
[RFC5441] suggested the use of IRO to indicate the sequence of [RFC5441] describes the use of IRO to indicate the sequence of
domains to be traversed during inter-domain path computation. domains to be traversed during inter-domain path computation.
In order to discover the current state of affairs amongst During recent discussions, it was determined that there was a need to
implementations a survey of the existing and planned implementations define a standard representation to ensure interoperability. In
was conducted. This survey [I-D.dhody-pce-iro-survey] was informal order to understand the current usage amongst implementations, a
and conducted via email. Responses were collected and anonymized by survey of existing and planned implementations was conducted. This
the PCE working group chair. survey was informal and conducted via email. Responses were
collected and anonymized by the PCE working group chair.
During discussion of [I-D.ietf-pce-pcep-domain-sequence] it was
proposed to have a new IRO type with ordered nature, as well as
handling of Loose bit (L bit); however, with the update to [RFC5440]
described in this document, no new IRO type is needed.
This document updates the IRO specifications in section 7.12 of This document updates the IRO specifications in section 7.12 of
[RFC5440] as per the conclusion and action points presented in [RFC5440] as per the conclusion of the survey.
[I-D.dhody-pce-iro-survey].
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Update in IRO specification 2. Update in IRO specification
Section 7.12 of [RFC5440] describes IRO as an optional object used to Section 7.12 of [RFC5440] describes the IRO as an optional object
specify a set of network elements to be traversed in the computed used to specify a set of network elements to be traversed in the
path. It also states that the Loose bit (L bit) in sub-object has no computed path. It stated that the Loose hop bit (L bit) in the sub-
meaning within an IRO. It did not mention if IRO is an ordered or object has no meaning within an IRO. It did not mention if the IRO
un-ordered list of sub-objects. contains an ordered or un-ordered list of sub-objects.
A survey of the existing and planned implementations was conducted in A survey of the existing and planned implementations was conducted in
order to discover the current state of affairs amongst order to understand the current state of usage amongst
implementations. [I-D.dhody-pce-iro-survey] describe the implementations.
questionnaire, results and presents some conclusions and proposed
action items.
The survey suggest that most implementations construct or interpret The survey found that most implementations construct or interpret the
IRO in an ordered fashion and consider it to be an ordered list. IRO in an ordered fashion and consider it to be an ordered list.
More than half of implementation under survey consider the IRO sub- More than half of implementations interpreted the IRO sub-objects as
objects as strict hops, others consider loose or support both. The strict hops, others interpreted as loose or supported both
results shown in this survey seems to suggest that most interpretation. The results shown in this survey found that most
implementations would be fine with updating [RFC5440] to specify IRO implementations support updating [RFC5440] to specify the IRO as an
as an ordered list as well as to enable support for Loose bit (L bit) ordered list and supported the use of the Loose hop bit (L bit) such
such that both strict and loose hops could be supported in the IRO. that both strict and loose hops could be supported in the IRO.
2.1. Update to RFC 5440 2.1. Update to RFC 5440
Section 7.12 of [RFC5440] regarding the IRO specification is updated Section 7.12 of [RFC5440] regarding the IRO specification is updated
to remove the last line in the section 7.12 of [RFC5440], that states to remove the last line in the section 7.12 of [RFC5440], that states
- "The L bit of such sub-object has no meaning within an IRO." - 'The L bit of such sub-object has no meaning within an IRO.'
Further, the Section 7.12 of [RFC5440] is updated to add following Further, the Section 7.12 of [RFC5440] is updated to add the
two statements - following two statements -
- The content of IRO is an ordered list of sub-objects representing a - The content of IRO is an ordered list of sub-objects representing a
series of abstract nodes. An abstract node could just be a simple series of abstract nodes. An abstract node could be a simple
abstract node comprising one node or a group of nodes for example an abstract node comprising one node or a group of nodes, for example an
AS (comprising of multiple hops within the AS) (refer section 4.3.2 AS (comprising of multiple hops within the AS) (refer section 4.3.2
of [RFC3209]). of [RFC3209]).
- The L Bit of IRO sub-object is set based on the loose or strict - The L Bit of IRO sub-object is set based on the loose or strict hop
property of the sub-object, which is set if the sub-object represents property of the sub-object, it is set if the sub-object represents a
a loose hop. If the bit is not set, the sub-object represents a loose hop. If the bit is not set, the sub-object represents a strict
strict hop. The interpretation of Loose bit (L bit) is as per hop. The interpretation of Loose bit (L bit) is as per section
section 4.3.3.1 of [RFC3209]. 4.3.3.1 of [RFC3209].
3. Other Considerations 3. Other Considerations
Based on the survey [I-D.dhody-pce-iro-survey], it should be noted Based on the survey, it should be noted that most implementations
that most implementation already support the update in the IRO already support this update in the IRO specification. The other
specification as per this document. The other implementation are implementations are expected to make an update to the IRO procedures
expected to make an update to the IRO procedures based on this based on this document.
document.
During the survey it was also noted that minority of the During the survey, it was also noted that a minority of the
implementations, interpreted the IRO sub-objects as loose, when these implementations, interpreted the IRO sub-objects as loose. When
implementation interwork with an implementation conforming to this these implementations interwork with an implementation conforming to
document, the following impact might be seen - this document, the following impact might be seen -
o If a non-conforming (to this document) PCC sends an IRO, to a o If a non-conforming (to this document) PCC sends an IRO, to a
conforming (to this document) PCE, then the PCE may unexpectedly conforming (to this document) PCE, then the PCE may unexpectedly
fail to find a path (since the PCC may think of IRO sub-objects as fail to find a path (since the PCC may think of IRO sub-objects as
loose hops, but the PCE interprets them as strict hops). loose hops, but the PCE interprets them as strict hops).
o If a conforming PCC sends an IRO containing strict hops to a non- o If a conforming PCC sends an IRO containing strict hops to a non-
conforming PCE, then the PCE may erroneously return a path that conforming PCE, then the PCE may erroneously return a path that
does not comply with the requested strict hops (since PCE does not comply with the requested strict hops (since the PCE
interprets them all as loose hops). The PCC may check the interprets them all as loose hops). The PCC may check the
returned path and find the issue or it may end up using incorrect returned path and find the issue or it may end up using an
path. incorrect path.
Thus it is RECOMMENDED that network operators ensure that all PCEP Thus it is RECOMMENDED that network operators ensure that all PCEP
speakers in their network conform to this document with updated IRO speakers in their network conform to this document if they intend to
specification if they intend to use IRO. use IRO.
4. Security Considerations 4. Security Considerations
This update in IRO specification does not introduce any new security This update in IRO specification does not introduce any new security
considerations, apart from those mentioned in [RFC5440]. considerations, apart from those mentioned in [RFC5440].
Clarification in the supported IRO ordering or Loose bit handling Clarification in the supported IRO ordering or Loose hop bit handling
will not have any negative security impact. will not have any negative security impact.
It is worth noting that PCEP operates over TCP. An analysis of the It is worth noting that PCEP operates over TCP. An analysis of the
security issues for routing protocols that use TCP (including PCEP) security issues for routing protocols that use TCP (including PCEP)
is provided in [RFC6952], while [I-D.ietf-pce-pceps] discusses an is provided in [RFC6952].
experimental approach to provide secure transport for PCEP.
5. IANA Considerations 5. IANA Considerations
This document makes no requests to IANA for action. This document makes no requests to IANA for action.
6. Acknowledgments 6. Acknowledgments
A special thanks to PCE chairs for guidance regarding this work. A special thanks to PCE chairs for guidance regarding this work.
Thanks to Francesco Fondelli for his suggestions in clarifying the L Thanks to Francesco Fondelli for his suggestions in clarifying the L
skipping to change at page 6, line 30 skipping to change at page 6, line 25
Traffic Engineering Label Switched Paths", RFC 5441, Traffic Engineering Label Switched Paths", RFC 5441,
DOI 10.17487/RFC5441, April 2009, DOI 10.17487/RFC5441, April 2009,
<http://www.rfc-editor.org/info/rfc5441>. <http://www.rfc-editor.org/info/rfc5441>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<http://www.rfc-editor.org/info/rfc6952>. <http://www.rfc-editor.org/info/rfc6952>.
[I-D.ietf-pce-pcep-domain-sequence]
Dhody, D., Palle, U., and R. Casellas, "Domain Subobjects
for Path Computation Element (PCE) Communication Protocol
(PCEP).", draft-ietf-pce-pcep-domain-sequence-12 (work in
progress), December 2015.
[I-D.ietf-pce-pceps]
Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure
Transport for PCEP", draft-ietf-pce-pceps-07 (work in
progress), January 2016.
[I-D.dhody-pce-iro-survey]
Dhody, D., "Informal Survey into Include Route Object
(IRO) Implementations in Path Computation Element
communication Protocol (PCEP)", draft-dhody-pce-iro-
survey-02 (work in progress), December 2014.
Author's Address Author's Address
Dhruv Dhody Dhruv Dhody
Huawei Technologies Huawei Technologies
Divyashree Techno Park, Whitefield Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037 Bangalore, Karnataka 560066
India India
EMail: dhruv.ietf@gmail.com EMail: dhruv.ietf@gmail.com
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