Requirement for Information extension in electro-optical multi-layer network
draft-xie-ccamp-elec-opt-network-info-ext-req-00

Abstract

This memo provides extending information for electro-optical multi-layer network under the control of Generalized MPLS(GMPLS). In particular we provide electro-optical conversion capability that describes the function between Optical Cross Connect(OXC) and Digital Cross Connect(DXC). The information of electro-optical conversion capability is used for extending multi-layer network(MLN) information model and Wavelength Switched Optical network(WSON) information model.

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 (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.) [RFC2119].

Status of this Memo

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Table of Contents

1.  Introduction
2.  Motivation
3.  Information extension
    3.1.  Extending information
    3.2.  Extending mode
    3.3.  Extending protocols
4.  Example
5.  Security Considerations
6.  IANA Considerations
7.  Acknowledgments
8.  References
    8.1.  Normative References
    8.2.  Informative References
§  Authors' Addresses

1.  Introduction

A multi-layer network (MLN) is a Traffic Engineering (TE) domain comprising multiple data plane switching layers either of the same ISC (e.g., TDM) or different ISC (e.g., TDM and PSC) and controlled by a single GMPLS control plane instance[RFC5212]. In a MLN, network elements may be single-switching-type-capable or multi-switching-type-capable nodes. Single-switching-type-capable nodes have TE links with the same ISC value. Multi-switching-type-capable nodes have TE links with the different ISCs value. Nodes are classified as "simplex" or "hybrid" nodes. A simplex node can terminate data links with different switching capabilities where each data link is connected to the node by a separate link interface. A hybrid node can terminate data links with different switching capabilities where the data links are connected to the node by the same interface.

Interface Switching Capability Descriptor(ISCD) is defined to describe the ISC of link RFC 4203 (Kompella, K. and Y. Rekhter, “OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS),” October 2005.) [RFC4203]. In a MLN without hybrid nodes, ISCs at both ends of the link are different if the link is between two different ISC nodes. For example, [TDM, LSC] is a link between a Digital Cross Connect(DXC) and an Optical Cross Connect(OXC) RFC 4202 (Kompella, K. and Y. Rekhter, “Routing Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS),” October 2005.) [RFC4202]. For a hybrid node, Interface Adjustment Capability Descriptor (IACD) is the capability of the internal adjustment capability between two link ends with different ISC. For example, in a hybrid node with a DXC and a OXC that interconnect with the internal links, IACD will be add to the routing information of a TE link which ISC is LSC.

Since optical network is block, so we need flood the block information in the optical network. Wavelength Switched Optical Network(WSON) extend the block information.

But electro-optical multi-layer network need more information. This document defines the information extension of electro-optical network.

2.  Motivation

A MLN with optical network and electronic network is shown in Figure 1.

      Node A             Node B             Node C             Node D
     --------           --------           --------           --------
    |        |if-1     |        |if-3     |        |if-5     |        |
    |  DXC   |---------|  OXC   |---------|  OXC+  |---------|  OXC+  |
    |        |     if-2|        |     if-4|  DXC   |     if-6|        |
     --------           --------           --------           --------
     if-7|                                    |if-13             |if-12
         |                                    |                  |
         |                               if-14|                  |
         |              --------           --------              |
         |         if-8|        |if-9     |        |             |
         +-------------|  OXC   |---------|  OXC   |-------------+
                       |        |    if-10|        |if-11
                        --------           --------
                         Node E             Node F

Node C is a hybrid node and other nodes are single-switching-type-nodes. So we can get four paths: A-B-C-D, A-B-C-F-D, A-E-F-D, A-E-F-C-D. In case that electro-optical conversion is at if-2, if-8, if-11 and the internal links within node c. And in case the modulation type of if-2 and if-8 is DPSK and the modulation type of if-11 is DQPSK. In node C, the modulation type of some internal links is DPSK and the modulation type of others is DQPSK. So A-E-F-D is not available and others are not sure to be available.

Since optical network is blocking, the blocking information need to be described. The typical node model of optical network is shown if figure 2.

        ......................................................
       :                        ROADM                        :
       :                                                     :
       :   ---      --------                           ---   :
       :  |   |    |        |    -----------------    |   |  :
       :  | D |--->|        |-->| Wavelength Conv |-->|   |  :
       :  | E |    |        |    -----------------    | M |  :
  ------->| M |    | N x N  |    -----------------    | U |------->
       :  | U |--->|        |-->|   Regeneration  |   | X |  :
       :  | X |    |        |    -----------------    |   |  :
       :  |   |    |        |                         |   |  :
       :  |   |--->|        |------------------------>|   |  :
       :   ---      --------                           ---   :
       :.............| | ^ ^.................................:
                     | | | |
                     v v | |
                     D D A A
                     r r d d
                     o o d d
                     p p 2 2
                     2 2 3 4
                     1 2

WSON extends the blocking information, including connectivity, wavelength conversion capability and regeneration capability. But from the WSON information model, there are no information that describes electro-optical conversion capability with add ports and drop ports.

So we need extend MLN information model and WSON information model to apply for electro-optical network.

3.  Information extension

3.1.  Extending information

In the optical network, optical transmitter(OT) and optical receiver(OR) are used for optical-electronic converting. The characteristics of optical transmitter and optical receiver include tunable or not, tuning range, tuning time, modulation type, Forward Error Correction(FEC) type, signal type and so on. Every characteristic is optional. More than one type of modulation/FEC/signal can be supported by optical transmitter and optical receiver.

The main extending information is electro-optical conversion information that includes wavelength tunable capability and signal processing capability. Wavelength tunable capability describes the wavelength tuning technology of optical transmitter. And signal processing capability describes the technology of electronic signal processing of optical transmitter or optical receiver. Wavelength tunable capability includes tunable or not, tuning range and tuning time. Signal processing capability includes FEC technology, modulation technology and electronic signal type.

<Wavelength tunable capability>::=<Tunable><Tuning range><Tuning time>;
<Electro-optical conversion capability>::=<FEC type list><Modulation type list><Signal type list>;

For hybrid node, we need extend information of internal links. And each internal link has a group of optical transmitter and optical receiver, so internal link information includes wavelength tunable capability and electro-optical conversion capability.

<Internal link>::=<link ID><Wavelength tunable capability><Electro-optical conversion capability>;
<Internal link list>:=<Internal link><Internal link list>;

3.2.  Extending mode

In different scenarios, we have different extending modes. In the electro-optical multi-layer network without hybrid nodes, there is a link between optical node and electronic node. If optical transmitter and optical receiver are at optical node side port or electronic node side port, electro-optical conversion information will be add to the routing information of optical node side port or electronic node side port. For example, if optical transmitter and optical receiver are at optical node side port, electro-optical conversion information will be add to the routing information of optical node side port. This scenario is shown in figure 3. And optical transmitter and optical receiver are at electronic node side port, electro-optical conversion information will be add to the routing information of electronic node side port. This scenario is shown in figure 4.

        ......................              .............
       :       Node B        :              :   Node A  :
       :                     :              :           :
       :   -----             :              :   -----   :
       :  |     |     ----   :              :  |     |  :
       :  |     |<---| OT |<-------------------|     |  :
       :  | OXC |     ----   :              :  | DXC |  :
       :  |     |     ----   :              :  |     |  :
       :  |     |--->| OR |------------------->|     |  :
       :  |     |     ----   :              :  |     |  :
       :   -----             :              :   -----   :
       :.....................:              :...........:

        ............                .................
       :   Node B  :               :     Node A     :
       :           :               :                :
       :   -----   :               :        -----   :
       :  |     |  :               :  ---- |     |  :
       :  |     |<-------------------| OT ||     |  :
       :  | OXC |  :               :  ---- | DXC |  :
       :  |     |  :               :  ---- |     |  :
       :  |     |------------------->| OR ||     |  :
       :  |     |  :               :  ---- |     |  :
       :   -----   :               :        -----   :
       :...........:               :................:

So link information will include wavelength tunable capability and signal processing capability, which is flooded by route protocol.

<Link Info>::=<ISCD><Wavelength tunable capability><Signal processing capability>;

For the hybrid node, electro-optical conversion information will be add to information of internal links. This scenario is shown in figure 5.

<Node Info>::=<Internal link list>;

        ..................
       :      Node C     :
       :                 :
       :   -----------   :
       :  |           |  :
       :  |   OXC     |  :
       :  |           |  :
       :   -----------   :
       :    ^      | Internal Link
       :    |      v     :
       :   ----   ----   :
       :  | OT | | OR |  :
       :   ----   ----   :
       :   -----------   :
       :  |           |  :
       :  |   DXC     |  :
       :  |           |  :
       :   -----------   :
       :.................:

3.3.  Extending protocols

There are some protocols which need be extended.

• OSPF or ISIS need be extended;
• Signal protocol need be extend to inform the internal link when LSP is creating;
• PCEP protocol need be extended to inform the internal link when PCE is used for path computation.

4.  Example

We use modulation type for example. For figure 1, the link information will be extended.

<Link Info(if-2)>::=<ISCD(LSC)><Wavelength tunable capability ><electro-optical conversion capability(DPSK)>;
<Link Info(if-8)>::=<ISCD(LSC)><Wavelength tunable capability ><electro-optical conversion capability(DPSK)>;
<Link Info(if-11)>::=<ISCD(LSC)><Wavelength tunable capability ><electro-optical conversion capability(DQPSK)>;

The hybrid node model is shown in figure 6.

        .............................................................
       :                             ROADM                          :
       :                                                            :
       :   ---      ---------------                           ---   :
       :  |   |    |               |    -----------------    |   |  :
       :  | D |--->|               |-->| Wavelength Conv |-->|   |  :
  if-4 :  | E |    |               |    -----------------    | M |  : if-13
  ------->| M |    |     N x N     |    -----------------    | U |------->
       :  | U |--->|               |-->|   Regeneration  |   | X |  :
       :  | X |    |               |    -----------------    |   |  :
       :  |   |    |               |                         |   |  :
       :  |   |--->|               |------------------------>|   |  :
       :   ---      ---------------                           ---   :
       :.............|...|...^...^..................................:
                     |   |   |   |
                     v   v   |   | Internal Link 31, 32
                     -   -   -   -
                    |O| |O| |O| |O|
                    |R| |R| |T| |T|
                    |1| |2| |1| |2|
                     -   -   -   -
                     -------------
                    |             |if-5
                    |    DXC      |<------->
                    |             |
                     -------------

In case modulation type of optical transmitter 1 and optical receiver 1 is DPSK, and modulation type of optical transmitter 1 and optical receiver 1 is DQPSK. Internal link 31 is identified as optical transmitter 1, optical receiver 1, drop port 21 and add port 23. And internal link 31 is identified as optical transmitter 1, optical receiver 1, drop port 21 and add port 23.

<Node Info>::=<Internal link(31)><Internal link(32)>;
<Internal link(31)>::=<Link ID(31)><Wavelength tunable capability ><Electro-optical conversion capability(DPSK)>;
<Internal link(31)>::=<Link ID(31)><Wavelength tunable capability ><Electro-optical conversion capability(DQPSK)>;
<Link info(if-4)>::=<ISCD(LSC)><IACD(TDM/LSC)>;
<Link info(if-13)>::=<ISCD(LSC)><IACD(TDM/LSC)>;
<Link info(if-5)>::=<ISCD(LSC)><IACD(TDM/LSC)>;

Finally, the available paths are:

Path 1: A.1-B.2-B.3-C.4(-C.31)-C.5-D.6; In node C, the internal link 31 is used.

Path 2: A.1-B.2-B.3-C.4(-C.31-C.32)-C.13-F.14-F.11-D.6; In node C, the internal link 31 and internal link 32 are used.

Path 3: A.7-E.8-E.9-F.10-F.14-C.13(-C.31)-C.5-D.6; In node C, the internal link 31 is used.

5.  Security Considerations

The use of control plane protocols for signaling, routing, and path computation opens an electro-optical network to security threats through attacks on those protocols. The data plane technology for an electro-optical network does not introduce any specific vulnerabilities, and so the control plane may be secured using the mechanisms defined for the protocols discussed.

For further details of the specific security measures refer to the documents that define the protocols ([RFC3473], [RFC4203], [RFC4205], [RFC4204], and [RFC5440]). [GMPLS-SEC] provides an overview of security vulnerabilities and protection mechanisms for the GMPLS control plane.

6.  IANA Considerations

This document makes not requests for IANA action.

7.  Acknowledgments

We'd be appreciated to thank Malcolm Betts for his review and useful comments.

8.  References

8.1. Normative References

8.2. Informative References

Authors' Addresses