Internet DRAFT - draft-fuxh-pce-boundary-explicit-control-framework

draft-fuxh-pce-boundary-explicit-control-framework






Network Working Group                                              X. Fu
Internet-Draft                                                    X. Lin
Intended status: Standards Track                                  G. Xie
Expires: September 9, 2010                               ZTE Corporation
                                                           March 8, 2010


A Framework for Explicit Control of Region Boundary in PCE-Based Inter-
                           Layer Architecture
         draft-fuxh-pce-boundary-explicit-control-framework-01

Abstract

   This document defines the framework for explicit control of region
   boundary in PCE-based inter-layer architecture.

Conventions Used In This Document

   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 RFC 2119 [RFC2119].

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on September 9, 2010.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the



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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Explicit Control of Region Boundary  . . . . . . . . . . . . .  3
     2.1.  Procedure for Region Boundary Explicit Contorl . . . . . .  3
   3.  Explicit Control Model of Region Boundary  . . . . . . . . . .  4
     3.1.  Explicit Region Control in Single PCE Inter-Layer  . . . .  4
     3.2.  Explicit Region Control in Multiple PCE Inter-Layer
           with inter-PCE communication.  . . . . . . . . . . . . . .  7
     3.3.  Explicit Region Control in Multiple PCE Inter-Layer
           without inter-PCE communication. . . . . . . . . . . . . .  9
   4.  Protocol Extension Requirements for Explicit Control of
       Region Boundary  . . . . . . . . . . . . . . . . . . . . . . . 11
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12



















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1.  Introduction

   PCE can determine regions' boundaries.  Without cooperating with VNTM
   or policy configuration, a intermediate LSR has to determine regions'
   boundaries by using the IGP database and ERO as described in
   [RFC4206] in order to trigger the lower layer signaling.  A
   centralized routing and distributed signaling application is foreseen
   in the PCE architecture.  Without any or enough TED within the
   intermediate LSR, it could not determine regions' boundaries during
   the signaling.

   This document defines the framework for explicit control of region
   boundary in PCE-based inter-layer architecture.  The solution isn't
   limited to specific Inter-Layer Path Computation and Inter-Layer Path
   Control Models.  The solution in this document can also be applied in
   the situation where TED can be maintained by the intermediate LSR in
   order for less signaling time.


2.  Explicit Control of Region Boundary

   PCE can determine regions' boundaries.  After PCE compute an end-to-
   end paths across multi-layer, multi-layer EROs must be carried in
   PCRep and Path message in terms of RFC5623.  In order to explicit
   control of regions' boundaries, this document introduces a new object
   (ERBO- Explicit Region Boundary Object).  It is carried in PCRep and
   RSVP-TE Signaling message.  Regions' boundaries must be carried in
   ERBO.

2.1.  Procedure for Region Boundary Explicit Contorl

   PCC request the PCE computate a multi-layer path with an indication
   of whether inter-layer path computation is allowed.  The PCE computes
   and returns a multi-layer path to the PCC converted to an Explicit
   Route Object (ERO) for use in RSVP-TE signaling.  The PCRep also must
   includs the region boundaries information which contains zero or
   multiple pairs of nodes.  This document introduces a new object
   (ERBO- Explicit Region Boundary Object).  It is carried in PCRep and
   RSVP-TE Signaling message.  Regions' boundaries must be carried in
   ERBO.  One pairs or multiple pairs of nodes within the ERBO can
   belong to the same layer or different layers.  The RSVP-TE signaling
   message among the PCC and intermediate nodes must carry the region
   boundaries information provided by PCE.

   If the intermediate nodes receive the signaling message with region
   boundaries information, it must check whether it is one of the region
   boundaries.  If it isn't one of region boundaries, the signaling
   should be continued.  If the intermediate nodes receive the signaling



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   message without region boundaries information, the signaling should
   be continued.

   If it is one of region boundaries, it must get another end of region
   boundary from the next hop in ERBO.  It must get the detailed routing
   information between the pair of region boundaries from the ERO in
   order to initiate the signaling of lower layer path.  Because there
   may be more further region boundaries information within the lower
   layer in ERBO, it must get the region boundaries information for
   lower layers from ERBO.

   Once the pair of region boundaries, the region boundaries information
   of lower layers and the routing information of lower layers are
   determined, the ingress node of region boundaries initiates the lower
   layer signaling.  The signaling of lower layers must also include the
   region boundaries information.


3.  Explicit Control Model of Region Boundary

3.1.  Explicit Region Control in Single PCE Inter-Layer

   Because inter-layer path computation is performed by a single PCE
   that has topology visibility into all layers in this model, PCE can
   determines the region boundaries within all the layers.  It must
   return the detailed routing information in ERO and region boundaries
   information in ERBO.

   PCC initiates the signaling based on the ERO and ERBO returned by the
   PCE.  The intermediate nodes will initiate the signaling procedure of
   lower layers based on the routing information in ERO and the region
   boundaries information in ERBO.

   The process of creating a LSP from H1 to H6 based on the following
   figure is as follows:

   1.  H1 sends a route request between H1 and H6 to PCE,and PCE
       responses to H1 with ERO = {H1,H2,L3,L4,H5,H6} and ERBO =
       {H2,H5}.

   2.  H1 Sends Path to H2 with ERO = {H2,L3,L4,H5,H6} and ERBO = {H2,
       H5}.

   3.  After H2 receivs the Path message, H2 confirm that it is the
       initiator of lower layer LSP and H5 is another end of region
       boundaries in terms of the ERBO and ERO.  H2 extracts the
       complete route of the lower layer LSP from ERO in terms of the
       other end of the region boundaries.  The routing information of



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       lower layer is {H2,L3,L4,H5}.  There is no any further region
       boundaries information within lower layer based on the ERBO.

   4.  Then H2 starts the creation of lower layer LSP, the route is
       H2,L3,L4,H5.

   5.  After the creation of the lower layer LSP, the Higher-Layer LSP's
       creation is to be continued.  H2 sends the Path message to H5.
       And the ERO and ERBO in the Path message is cut out.  So there
       isn't any information in ERBO.









































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      -----
     | PCE |
      -----
      ^    |
      |  2:PCRep
      |    | (ERO)  (ERBO)
      |    |  ----   ----
      |    | | H1 | | H2 |
      |    |  ----   ----
      |    | | H2 | | H5 |
      |    |  ----   ----
      |    | | L3 |
      |    |  ----
      |    | | L4 |
      |    |  ----
      |    | | H5 |
      |    |  ----
      |    | | H6 |
      |    |  ----
      |    |
   1:PCReq |
      |    v
      -----    -----                  -----    -----
     | LSR |--| LSR |................| LSR |--| LSR |
     | H1  |  | H2  |                | H5  |  | H6  |
      -----    -----\                /-----    -----
                     \-----    -----/
                     | LSR |--| LSR |
                     | L3  |  | L4  |
                      -----    -----
    --------------->                --------------->
      3:Path                             4:Path
      (ERO) (ERBO)                       (ERO)
      ----   ----                         ----
     | H2 | | H2 |                       | H2 |
      ----   ----                         ----
     | L3 | | H5 |
      ----   ----
     | L4 |
      ----
     | H5 |
      ----
     | H6 |
      ----







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3.2.  Explicit Region Control in Multiple PCE Inter-Layer with inter-PCE
      communication.

   In the following figure, there are two PCEs with inter-PCE
   communication.  PCE Hi has the topology visibility restricted to the
   upper layer.  PCE Lo has the topology visibility of two layers.  The
   end-to-end path is computated by the cooperation between PCE Hi and
   PCE Lo.

   The region boundaries within all the layers can be determined by the
   cooperation between the PCE Hi and PCE Lo.  The PCE Hi must return
   the detailed routing information in ERO and region boundaries
   information in ERBO.

   PCC initiates the signaling based on the ERO and ERBO returned by the
   PCE.  The intermediate nodes will initiate the signaling procedure of
   lower layers based on the routing information in ERO and the region
   boundaries information in ERBO.

   The process of creating a LSP from H1 to H10 is as follows:

   1.   H1 sends a route request bwtween H1 and H10 to PCE Ho.  Without
        the topology visibility of lower layers, PCE Ho has to compute a
        multi-layer path with inter-communication with PCE Lo.  PCE Lo
        computes two multi-layer paths.  One is between H2 and H5.
        Another is between H6 and H9.  PCE Lo responses to PCE Hi with
        the derailed routing information and region boundaries
        information.  In the end, PCE Hi responses to H1 with ERO =
        {H1,H2,L3,M1,M2,L4,H5,H6,L7,L8,H9,H10} and ERBO
        ={H2,H5,L3,L4,H6,H9}.

   2.   H1 Sends Path to H2 with ERO =
        {H2,L3,M1,M2,L4,H5,H6,L7,L8,H9,H10}, ERBO = {H2,H5,L3,L4,H6,H9}

   3.   After H2 receives the Path, H2 determines it is the one end of
        region boundaries and H5 is another end based on the ERO and
        ERBO.  So it abstracts the derailed routing information and
        region boundaries information of lower layer.  The region
        boundaries information is {L3,L4}.  It is to create lower layer
        LSP with ERO = {H2,L3,M1,M2,L4,H5} and ERBO = {L3,L4}.

   4.   H2 Sends Path to L3 with ERO = {L3,M1,M2,L4,H5} and ERBO =
        {L3,L4}.

   5.   After L3 receives the Path, L3 determines it is the one end of
        region boundaries and L4 is another end based on the ERO and
        ERBO.  So it abstracts the derailed routing information and
        region boundaries information of lower layer.  The routing



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        information of lower layer is {L3,M1,M2,L4}.  The region
        boundaries information is empty.  L3 is to create lower layer
        LSP with ERO = {L3,M1,M2,L4}.

   6.   L3 Sends Path to M1 with ERO = {M1,M2,L4} and ERBO = empty.

   7.   After the creation of the lower layer LSP between L3 and L4, L3
        continues to send Path to L4 with ERO = {L4,H5} and ERBO =
        empty.

   8.   After the creation of the lower layer LSP between H2 and H5, H2
        continues to send Path to H5 with ERO = {H5,H6,L7,L8,H9,H10} and
        ERBO = {H6,H9}.

   9.   H5 send the Path message to H6 with the with ERO =
        {H6,L7,L8,H9,H10} and ERBO = {H6,H9}.

   10.  After H6 receives the Path, H6 determines it is the one end of
        region boundaries and H9 is another end based on the ERO and
        ERBO.  So it abstracts the derailed routing information and
        region boundaries information of lower layer.  The routing
        information of lower layer is {H6,L7,L8,H9}.  The region
        boundaries information is empty.  H6 create the lower layer LSP
        with ERO = {H6,L7,L8,H9} and ERBO = empty.

   11.  After the creation of the lower layer LSP between H6 and H9, the
        higher layer LSP's creation is to be continued.
























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   -----
  | PCE |
  | Hi  | <----------------------
   -----                        |
   ^    |                       |
   |    |                       |
   |    |                       |
   |    |                       |
   |    |                       |
   |    v                       |
    -----    -----              |                -----    -----                -----    -----
   | LSR |--| LSR |.............|...............| LSR |--| LSR | .............| LSR |--| LSR |
   | H1  |  | H2  |             v               | H5  |  | H6  |              | H9  |  | H10 |
    -----    -----\           -----             /-----    -----\              /-----    -----
                  |          | PCE |            |              |              |
                  |          | Lo  |            |              |              |
                  |           -----             |              |              |
                  \-----                  -----/               \-----    -----/
                  | LSR |................| LSR |               | LSR |..| LSR |
                  | L3  |                | L4  |               | L7  |  | L8  |
                   -----\                /-----                 -----    -----
                        |               |
                        |               |
                        |               |
                        \-----    -----/
                        | LSR |..| LSR |
                        | M1  |  | M2  |
                         -----    -----

3.3.  Explicit Region Control in Multiple PCE Inter-Layer without inter-
      PCE communication.

   In the following figure, the PCE Hi has the topology visibility of
   higher two layers.  The PCE Lo has the topology visibility of lower
   two layers.

   The process of creating a LSP from H1 to H10 is as follows:

   1.   H1 sends a route request between H1 and H10 to PCE Ho.  PCE Ho
        could not computate a multi-layer path within four layers.  PCE
        Ho computes a multi-layer path for higher two layers without
        inter-communication with PCE Lo, and responses to H1 with ERO =
        {H1,H2,M3,M8,H9,H10} and ERBO ={H2,H9}.

   2.   H1 Sends Path to H2 with ERO = {H2,M3,M8,H9,H10} and ERBO =
        {H2,H9}.





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   3.   After H2 receives the Path, H2 determines it is the one end of
        region boundaries and H9 is another end based on the ERO and
        ERBO.  So it abstracts the derailed routing information and
        region boundaries information of lower layer.  The routing
        information of lower layer is {H2,M3,M8,H9}.  The region
        boundaries information is empty.  H2 is to create lower layer
        LSP with ERO = {H2,M3,M8,H9}.

   4.   H2 Sends Path to M3,with ERO = {M3,M8,H9} and ERBO = empty.

   5.   There is no any connectivity between M3 and M8.  M3 can
        communicates with PCE Lo.  PCE Lo has the capability of Inter-
        Layer path computation.  So M3 consults the PCE Lo with
        responsibility for the lower-layers network.  PCE Lo computes
        the route to expand the loose hop route (i.e., M3 and M8) in the
        higher-layer LSP and responses to M3 with ERO =
        {M3,L4,L5,L6,L7,M8}, ERBO ={L4,L7}.

   6.   M3 Sends Path to L4, with ERO = {L4,L5,L6,L7,M8}, ERBO =
        {L4,L7}.

   7.   After L4 receives the Path, L4 determines it is the one end of
        region boundaries and H7 is another end based on the ERO and
        ERBO.  So it abstracts the derailed routing information and
        region boundaries information of lower layer.  The routing
        information of lower layer is {L4,L5,L6,L7}.  The region
        boundaries information is empty.  L4 is to create lower layer
        LSP with ERO = {L4,L5,L6,L7} and ERBO = empty.

   8.   L4 Sends Path to L5, with ERO = {L5,L6,L7} and ERBO = empty.

   9.   After the creation of the lower layer LSP between L4 and L7, L4
        continues to send Path to L7 with ERO = {L7,M8} and ERBO =
        empty.

   10.  After the creation of the lower layer LSP between M3 and M8, M3
        continues to send Path to M8 with ERO = {M8,H9} and ERBO =
        empty.

   11.  After the creation of the lower layer LSP between H2 and H9, H2
        continues to send Path to H9 with ERO = {H9,H10} and ERBO =
        empty









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         -----
        | PCE |
        | Hi  |
         -----
        ^    |
        |    |
        |    |
        |    |
        |    |
        |    v
         -----    -----                                            -----    -----
        | LSR |--| LSR |..........................................| LSR |--| LSR |
        | H1  |  | H2  |                                          | H9  |  | H10 |
         -----    -----\                                          /-----    -----
                       |                                          |
                       |                                          |
                       |                                          |
                       \-----                               -----/
                       | LSR |............................ | LSR |
                       | M3  |<-------------               | M8  |
                        -----\             |               /-----
                             |             v               |
                             |            -----            |
                             |           | PCE |           |
                             |           | Lo  |           |
                             |            -----            |
                              \-----                 -----/
                              | LSR |...............| LSR |
                              | L4  |               | L7  |
                               -----\               /-----
                                    |               |
                                    |               |
                                    |               |
                                    \-----    -----/
                                    | LSR |..| LSR |
                                    | L4  |  | L7  |
                                     -----    -----


4.  Protocol Extension Requirements for Explicit Control of Region
    Boundary

   A requirements for PCRep (RFC5440) extensions to support explicit
   control of region boundary is foreseen.  A requirements for Path
   (RFC3473) extensions to support explicit control of region boundary
   is also foreseen.  A new object (ERBO) could be introduced in PCRep
   and Path message.  The format of new object is the same as an ERO.
   [draft-fuxh-ccamp-region-boundary-explicit-control-rsvp-ext-00]



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   defines the RSVP-TE signaling extension for explicit control of
   region boundary during the signaling procedure.
   [draft-fuxh-pce-region-boundary-explicit-control-pcep-ext-00] defines
   the PCEP protocol extension for explicit control of region boundary
   in PCE-based inter-layer architecture.


5.  Security Considerations

   TBD


6.  IANA Considerations

   TBD


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.

   [RFC4206]  Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP)
              Hierarchy with Generalized Multi-Protocol Label Switching
              (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.

7.2.  Informative References


Authors' Addresses

   Xihua Fu
   ZTE Corporation
   West District,ZTE Plaza,No.10,Tangyan South Road,Gaoxin District
   Xi An  710065
   P.R.China

   Phone: +8613798412242
   Email: fu.xihua@zte.com.cn
   URI:   http://wwwen.zte.com.cn/









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   Xuefeng Lin
   ZTE Corporation
   12F,ZTE Plaza,No.19,Huayuan East Road,Haidian District
   Beijing  100191
   P.R.China

   Phone: +8615901011821
   Email: lin.xuefeng@zte.com.cn
   URI:   http://www.zte.com.cn/


   Gang Xie
   ZTE Corporation
   12F,ZTE Plaza,No.19,Huayuan East Road,Haidian District
   Beijing  100191
   P.R.China

   Phone: +8613691280432
   Email: xie.gang@zte.com.cn
































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