Internet DRAFT - draft-dhody-pce-iro-update
draft-dhody-pce-iro-update
PCE Working Group D. Dhody
Internet-Draft Huawei Technologies
Updates: 5440 (if approved) December 30, 2014
Intended status: Standards Track
Expires: July 3, 2015
Update to Include Route Object (IRO) specification in Path Computation
Element communication Protocol (PCEP)
draft-dhody-pce-iro-update-02
Abstract
During discussions of a document to provide a standard representation
and encoding of Domain-Sequence within the Path Computation Element
(PCE) communication Protocol (PCEP) for communications between a Path
Computation Client (PCC) and a PCE, or between two PCEs. It was
determined that there was a need for clarification with respect to
the ordered nature of the Include Route Object (IRO).
An informal survey was conducted to determine the state of current
and planned implementation with respect to IRO ordering and handling
of Loose bit (L bit).
This document updates the IRO specification based on the survey
conclusion and recommendation.
Status of This Memo
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This Internet-Draft will expire on July 3, 2015.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Update in IRO specification . . . . . . . . . . . . . . . . . 3
3. Other Considerations . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Appendix A. Details of IRO survey . . . . . . . . . . . . . . . 6
1. Introduction
The Path Computation Element Communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path
computations in response to Path Computation Clients (PCCs) requests.
[RFC5440] defines the Include Route Object (IRO) to specify that the
computed path must traverse a set of specified network elements. The
specification did not mention if IRO is an ordered or un-ordered list
of sub-objects. 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
domains to be traversed during inter-domain path computation.
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).
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In order to discover the current state of affairs amongst
implementations a survey of the existing and planned implementations
was conducted. This survey [I-D.dhody-pce-iro-survey] was informal
and conducted via email. Responses were collected and anonymized by
the PCE working group chair.
This document updates the IRO specifications in [RFC5440] as per the
conclusion and action points presented in [I-D.dhody-pce-iro-survey].
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. Update in IRO specification
[RFC5440] describes IRO as an optional object used to specify that
the computed path MUST traverse a set of specified network elements.
It further state that the Loose bit (L bit) of such sub-object has no
meaning within an IRO. It did not mention if IRO is an ordered or
un-ordered list of sub-objects.
A survey of the existing and planned implementations was conducted in
order to discover the current state of affairs amongst
implementations. [I-D.dhody-pce-iro-survey] describe the
questionnaire, results and presents some conclusions and proposed
action items. More details in Appendix A.
The survey suggest that most implementations construct or interpret
IRO in an ordered fashion and consider it to be an ordered list.
More than half of implementation under survey consider the IRO sub-
objects as strict hops, others consider loose or support both. The
results shown in this survey seems to suggest that most
implementations would be fine with updating [RFC5440] to specify IRO
as an ordered list as well as to enable support for Loose bit (L bit)
such that both strict and loose hops could be supported in the IRO.
This document thus updates [RFC5440] regarding the IRO specification
making IRO as an ordered list as well as support for Loose bit (L
bit).
The content of an IRO object is an ordered list of subobjects
representing a series of abstract nodes. An abstract node may just
be a simple abstract node comprising one node or a group of nodes for
example an AS (comprising of multiple hops within the AS) (refer
[RFC3209] for details). Further each subobject has an attribute
called 'L bit', which is set if the subobject represents a loose hop.
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If the bit is not set, the subobject represents a strict hop. The
interpretation of Loose bit (L bit) is as per section 4.3.3.1 of
[RFC3209].
3. Other Considerations
Based on the survey, it should be noted that most implementation
already support the update in the IRO specification as per this
document. The other implementation are expected to make an update to
the IRO procedures.
4. Security Considerations
This update in IRO specification does not introduce any new security
considerations, apart from those mentioned in [RFC5440].
Clarification in the supported IRO ordering or Loose bit handling
will not have any negative security impact.
It is worth noting that PCEP operates over TCP. An analysis of the
security issues for routing protocols that use TCP (including PCEP)
is provided in [RFC6952], while [I-D.ietf-pce-pceps] discusses an
experimental approach to provide secure transport for PCEP.
5. IANA Considerations
This informational document makes no requests to IANA for action.
6. Acknowledgments
A special thanks to PCE chairs for guidance regarding this work.
Thanks to Francesco Fondelli for his suggestions in clarifying the L
bit usage.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", RFC 5440, March
2009.
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7.2. Informative References
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC5441] Vasseur, JP., Zhang, R., Bitar, N., and JL. Le Roux, "A
Backward-Recursive PCE-Based Computation (BRPC) Procedure
to Compute Shortest Constrained Inter-Domain Traffic
Engineering Label Switched Paths", RFC 5441, April 2009.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, May 2013.
[I-D.ietf-pce-pcep-domain-sequence]
Dhody, D., Palle, U., and R. Casellas, "Standard
Representation Of Domain-Sequence", draft-ietf-pce-pcep-
domain-sequence-06 (work in progress), October 2014.
[I-D.ietf-pce-pceps]
Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure
Transport for PCEP", draft-ietf-pce-pceps-02 (work in
progress), October 2014.
[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.
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Appendix A. Details of IRO survey
During discussions of this document to provide a standard
representation and encoding of Domain-Sequence within PCEP. It was
determined that there was a need for clarification with respect to
the ordered nature of the IRO.
Since there was a proposal to have a new IRO type with ordering, as
well as handling of Loose bit, in an earlier version of this document
(refer - draft-ietf-pce-pcep-domain-sequence-05), it was deemed
necessary to conduct a survey of the existing and planned
implementations. An informal survey was conducted via email.
Responses were collected and anonymized by the PCE working group
chairs.
[I-D.dhody-pce-iro-survey] summarizes the survey questions and
captures the results. It further list some conclusions and action
points.
This document was considered as one possible venue to handle the
proposed action points.
Author's Address
Dhruv Dhody
Huawei Technologies
Leela Palace
Bangalore, Karnataka 560008
India
EMail: dhruv.ietf@gmail.com
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