RSVP-TE Signaling Extension for Explicit Control of LSP Boundary in A GMPLS-Based Multi-Region and Multi-Layer Networks (MRN/MLN)
draft-fuxh-ccamp-boundary-explicit-control-ext-01

Abstract

[RFC5212] defines a Multi-Region and Multi-Layer Networks (MRN/MLN). [RFC4206] introduces a region boundary determination algorithm and a Hierarchy LSP (H-LSP) creation method. However, in some scenarios, some attributes have to be attached with the boundary nodes in order to explicit control the hierarchy LSP creation. This document extends GMPLS signaling protocol for the requirement of explicit control the hierarchy LSP creation.

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Table of Contents

1.  Introduction
    1.1.  Conventions Used In This Document
2.  Requirement of Explicit Control of Hierarchy LSP Creation
    2.1.  Selection of Server Layer/Sub-Layer
    2.2.  Selection/Creation of FA-LSP based on characteristics of server layer
    2.3.  Configuration of Multi Stages Multipelxing Hierarchy
3.  Explicit Route Boundary Object (ERBO)
    3.1.  Server Layer/Sub-Layer Attributes TLV
    3.2.  Multiplexing Hierarchy Attribute TLV
    3.3.  Latency Attribute TLV
4.  Signaling Procedure
5.  Security Considerations
6.  IANA Considerations
7.  References
    7.1.  Normative References
    7.2.  Informative References
§  Authors' Addresses

1.  Introduction

[RFC5212] defines a Multi-Region and Multi-Layer Networks (MRN/MLN). [RFC4206] introduces a region boundary determination algorithm and a Hierarchy LSP (H-LSP) creation method. However, in some scenarios, some attributes have to be attached with the boundary nodes in order to explicitly control the hierarchy LSP creation. This document extends GMPLS signaling protocol for the requirement of explicit control the hierarchy LSP creation.

1.1.  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 [RFC2119].

2.  Requirement of Explicit Control of Hierarchy LSP Creation

2.1.  Selection of Server Layer/Sub-Layer

[RFC4206] describes a region boundary determination algorithm and a hierarchical LSP creation method. This region boundary determination algorithm and LSP creation method are well applied to Multi-Region Network. However it isn't fully applied to Multi-Layer Network. In the following figure, three LSPs belong to the same TDM region and different latyers, but the sub-layer boundary node could not determine which lower layer should be triggered according to the region boundary determination algorithm defined in [RFC4206]. Thus the higher layer (VC4 in figure 1) signaling can't trigger the lower layer (STM-N in figure 1) LSP creation. It needs to explicitly describe which sub-layer should be triggered in the signaling message.

  A           B           C           D            E           F
+---+ STM-N +---+ STM-N +----+ OTUk +----+ STM-N +---+ STM-N +---+
|VC4|-------|VC4|-------|ODUk|------|ODUk|-------|VC4|-------|VC4|
+---+       +---+       +----+      +----+       +---+       +---+

 |<-------------------------- VC4 LSP ------------------------->|

             |<------------- STM-N LSP ------------>|

                         |<--ODUk LSP-->|

2.2.  Selection/Creation of FA-LSP based on characteristics of server layer

ITU-T G.800 defines Composite Link. Individual component links in a composite link may be supported by different transport technologies such as OTN, MPLS-TP or SDH/SONET. Even if the transport technology implementing the component links is identical, the characteristics (e.g., latency) of the component links may differ. Operator may prefer its traffic to be transported over a specific transport technology server layer. Further more, operator may prefer its traffic to be transported over a specific transport technology component link with some specific characteristics (e.g.,latency). So it desires to explicitly control the component link selection based on the attributes (e.g., switching capability and latency) attached with the boundary nodes during the signaling.

Latency is a key requirement for service provider. Restoration and/or protection can impact "provisioned" latency. The key driver for this is stock/commodity trading applications that use data base mirroring. A few delicacy can impact a transaction. Therefore latency and latency SLA is one of the key parameters that these "high value" customers use to select a private pipe line provider. So it desires to explicitly convey latency SLA to the boundary nodes where the hierarchy LSP will be triggered.

                   ___                           ___
  MPLS-based LSP  |   |                         |   |
o-----o-----o-----|-o |                         | o-|-----o-----o-----o
                  |   |                         |   |
                  |   |OTN FA-LSP with latency 1|   |
                  | o-|-------------------------|-o |
                  |   |                         |   |
                  |   |OTN FA-LSP with latency 2|   |
                  | o-|-------------------------|-o |
                  | . |            .            | . |
                  | . |            .            | . |
                  | . |            .            | . |
                  |   |OTN FA-LSP with latency n|   |
                  | o-|-------------------------|-o |
                  |___|                         |___|

In Figure 2, a LSP traffic is over a composite link whose component links with different latency characteristic are supported by OTN. In order to meet the latency SLA, it needs to explicitly limit the latency between boundary nodes to create an OTN tunnel.

2.3.  Configuration of Multi Stages Multipelxing Hierarchy

In Figure 3, node B and C in the OTN network are connected to 2.5G TS network by two OTU3 link. They can support flexible multi stages multiplexing hierarchies. There are two multi stages multiplexing hierarchies for ODU0 being mapped into OTU3 link in B and C of Figure 1 (i.e., ODU0-ODU1-ODU3 and ODU0-ODU2-ODU3). So path computation entity has to determine which kind of multi stages multiplexing hierarchies should be used for the end-to-end ODU0 service and the type of tunnel (FA-LSP). In Figure 3, if path computation entity select the ODU0-ODU2-ODU3 multi stages multiplexing hierarch in Node B and C for one end-to-end ODU0 service from A to Z, there has to be an ODU2 tunnel between B and C. The selection of multi stages multiplexing hierarchies is based on the operator policy and the equipment capability. How to select the multiplexing hierarchies is the internal behavior of path computation entity.

                                      ODU1-ODU3
                                      ODU2-ODU3
            ODU0-ODU2            ODU0-ODU1-ODU3
            ODU1-ODU2            ODU0-ODU2-ODU3
         ODUflex-ODU2         ODUflex-ODU2-ODU3
                  |            _______        |
 ___             _|_____      /       \      _|_____             ___
| A |           | | B   |    |   40G   |    | | C   |           | Z |
| o-|-----------|-o   o-|----| Network |----|-o   o-|-----------|-o |
|___| OTU2 Link |_____|_|    |(2.5G TS)|    |_____|_| OTU2 Link |___|
      (1.25G TS)      |       \_______/           |   (1.25G TS)
                      |                           |
                      ODU0-ODU1-ODU3              ODU0-ODU2
                      ODU0-ODU2-ODU3              ODU1-ODU2
                      ODUflex-ODU2-ODU3           ODUflex-ODU2
                      ODU1-ODU2-ODU3
                      ODU1-ODU3
                      ODU2-ODU3

If path computation entity select the ODU0-ODU2-ODU3 for ODU0 being mapped into OTU3 Link, the multi stages multiplexing hierarchy has to be carried in signaling message to node B and C. After B receives the signaling message, it will triggered a creation of and ODU2 FA-LSP base on [RFC4206] and the selection of multi stages multiplexing hierarchy. Node B and C must config this kind of multi stages multiplexing hierarchy (i.e., ODU0-ODU2-ODU3) to its data plane. So data plane can multplex and demultiplex the ODU0 signal from/to ODU3 for a special end-to-end ODU0 service in terms of the control plane's configuration.

In Figure 4, the switching capability (e.g., TDM), switching granuality (i.e., ODU3) and multi stages multiplexing hierarchy (ODU0-ODU1-ODU3-ODU4) must be specified during signaling. Because the switching capability (TDM) and switching granuality (ODU3) information is not enough for data plane to know ODU0 is mapped into ODU3 tunnel by ODU0-ODU1-ODU3 then ODU4. In order to explicit specify multi stages multiplexing hierarchy, the switching capability, switching granuality and multi stages multiplexing hierarchy (ODU0-ODU1-ODU3) must be carried in the signaling message.

 2|0   0|2     2|0  0|1|3|4   4|3    3|4   4|3|1|0   0|2     2|0   0|2
  _______        _______        _______        _______        _______
 |   A   |      |   B   |      |   C   |      |   E   |      |   F   |
-|-o   o-|------|-o   o-|------|-o   o-|------|-o   o-|------|-o   o-|-
 |_______|      |_______|      |_______|      |_______|      |_______|

                               ODU3 Tunnel
ODU0 Service            -----------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                        -----------------------

3.  Explicit Route Boundary Object (ERBO)

In order to explicitly control hierarchy LSP creation, this document introduce a new object (ERBO- Explicit Route Boundary Object) carried in RSVP-TE message. The format of ERBO object is the same as ERO. The ERBO including the region boundaries information and some specific attributes (e.g., latency) can be carried in Path message. One pairs or multiple pairs of nodes within the ERBO can belong to the same layer or different layers.

This document introduce a new sub-object (BOUNDARY_ATTRIBUTES) carry the attributes of the associated hop specified in the ERBO. It allows the specification and reporting of attributes relevant to a particular hop of the signaled LSP. It follows an IPv4 or IPv6 prefix or unnumbered Interface ID sub-object in ERBO. A list of attribute TLV can be inserted into ERBO.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|    Type     |     Length    |           Reserved            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
~                         Attribute TLVs                        ~
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

-

This field indicates different attribute TLV sub-objects.

-

The total length of the sub-object in bytes, including the Type and Length fields. The value of this field is always a multiple of 4.

-

Attribute TLVs: This field carries different TLV according to the Type filed.

A list of attributes TLV can be inserted into ERBO. These attributes may represent the following information. It can be further extended to carry other specific requirement in the future.

-

Server Layer (e.g., PSC, L2SC, TDM, LSC, FSC) or Sub-Layer (e.g., VC4, VC11, VC4-4c, VC4-16c, VC4-64c, ODU0, ODU1, ODU2, ODU3, ODU4) used for boundary node to trigger one specific corresponding server layer or Sub-Layer FA-LSP creation. The region boundary node may support multiple interface switching capabilities and multiple switching granularities. It is very useful to indicate which server layer and/or sub-layer to be used at the region boundary node.

-

Multiplexing hierarchy (e.g., ODU0-ODU1-ODU3-ODU4) used for boundary node to configure it to the data plane and trigger one specific corresponding tunnel creation.

-

Server Layer and/or Sub-Layer's LSP Latency SLA (e.g., minimum latency value, maximum latency value, average latency value and latency variation value). Boundary node select a FA or create a FA-LSP based on the latency limitation.

The format of the Attributes TLV is as follows:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|           Type(IANA)          |           Length              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
//               Attribute Specific Information                //
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The following types are supported.

Type  |  Information
------+-------------------------------
TBD   |  server layer/sub-layer
TBD   |  server layer/sub-layer characteristics (e.g., latency)
TBD   |  multi stage multiplexing hierarchy

3.1.  Server Layer/Sub-Layer Attributes TLV

Switching capabilities and switching granularities of the region boundary can be carried in Attribute TLV. With these information carried in the RSVP-TE path message, the region boundary node can directly trigger one corresponding server layer or sub-layer FA-LSP creation which is defined in the Attribute TLV. The format of the Attribute TLV is shown below.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|         Type(IANA)            |           Length              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Server Layer  |   Sub-Layer   |           Reserve             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

• Type: indicates different values of Attribute TLV.
• Length: indicates the total length of this Attribute TLV value.
• Server Layer: Indicates which corresponding server layer should be triggered by the boundary node. The value of server layer is the same as the switching capability [RFC3471].
• Sub-Layer: If there are several sub-layers within one server layer, it can further indicates which sub-layer should be triggered by the boundary node.
  • SDH/SONET: VC4, VC11, VC12, VC4-4c, VC4-16c, VC4-64c.
  • OTN: ODU0, ODU1, ODU2, ODU3, ODU2e, ODU4, and so on

3.2.  Multiplexing Hierarchy Attribute TLV

Multiplexing Hierarchy Attribute TLV indicates the multiplexing hierarchies (e.g., ODU0-ODU2-ODU3) used for boundary node to configure it to the data plane and trigger one specific corresponding tunnel creation. The type of this sub-TLV will be assigned by IANA, and length is eight octets. The value field of this sub-TLV contains multi stages multiplexing hierachies constraint information of the link port.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|            Type (IANA)        |          Length               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| F |     Number    |  Reserve  |MSMH 1 |     ...MSMC 1...      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MSMH 2 |     ...MSMC 2...      |            ...                |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MSMH M |        ...MSMC M...       |           padding         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

• F (2 bits): Indicates the multi stages multiplexing hierarchies are included or excluded.
  • 0 - Inclusive Multiplexing Hierarchies:Indicates that the object/TLV contains one or more multi stages multiplexing hierarchies which can be supported.
  • 1 - Exclusive Multiplexing Hierarchies:Indicates that the object/TLV contains one or more multi stages multiplexing hierarchies which can't be supported.
• Number (8 bits): Indicates the total nunmber of multi stages multiplexing hierarchies which are supported or prohibited by the link port.
• Reserve (8 bits): for future use.
• (MSMH 1, MSMC 1), (MSMH 2, MSMC 2), ... ,(MSMH M, MSMC M): Indicates each multi stages multiplexing capability detailed information.
  • MSMH 1, MSMH2, ... , MSMH M (4 bits): Indicates the numbers of Multi Stages Multiplexing Hierarchies (MSMH).
    • MSMH = 1: It indicates ODUi is mapped into ODUk (k > i) by single stage multiplexing (e.g., ODU0-ODU3).
    • MSMH > 1: It indicates ODUi is mapped into ODUk (k > i) by multi stages multiplexing (e.g., ODU0-ODU1-ODU3).
  • MSMC 1, MSMC 2, ... ,MSMC M: Indicates the detailed information of multi stages multiplexing capability. The length of Multi Stages Multiplexing Capability (MSMC) information depends on the multi stages multiplexing hierarchies (MSMH). The length of MSMC is (MSMH+1) * 4. Each ODUk (k=1, 2, 3, 4, 2e, flex) is indicated by 4 bits. Following is the Signal Type for G.709 Amendment 3.

    
          Value   Type
          -----   ----
          0000    ODU0
          0001    ODU1
          0010    ODU2
          0011    ODU3
          0100    ODU4
          0101    ODU2e
          0110    ODUflex
          7-15    Reserved (for future use)
    

• The padding is used to make the Multi Stages Multiplexing Capability Descriptor sub-TLV 32-bits aligned.

3.3.  Latency Attribute TLV

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|            Type(IANA)         |           Length              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Minimum Latency Value                     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Maximum Latency Value                     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Average Latency Value                     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Latency Variation Value                   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

-

Minimum Latency Value: a minimum value indicates the latency performance parameters which server layer/sub-layer LSP must meet.

-

Maximum Latency Value: a maximum value indicates the latency performance parameters which server layer/sub-layer LSP must meet.

-

Average Latency Value: a average value indicates the latency performance parameters which server layer/sub-layer LSP must meet.

-

Latency Variation Value: a variation value indicates the latency performance parameters which server layer/sub-layer LSP must meet.

4.  Signaling Procedure

In order to signal an end-to-end LSP across multi layer, the LSP source node sends the RSVP-TE PATH message with ERO which indicates LSP route and ERBO which indicates the LSP route boundary. When a interim node receives a PATH message, it will check ERBO to see if it is the layer boundary node. If a interim node isn't a layer boundary, it will process the PATH message as the normal one of single layer LSP. If a interim node finds its address is in ERBO, it is a layer boundary node. So it will directly extract another boundary egress node and other detail Attribute TLV infomration (e.g., Latency) from ERBO. If it is necessary, it will also extract the server layer/sub-layer routing information from ERO based on a pair of boundary node. Then the layer boundary node holds the PATH message and selects or creates a server layer/sub-layer LSP based on the detailed information of Attribute TLV (e.g., Latency) carried in ERBO.

On reception of a Path message containing BOUNDARY_ATTRIBUTES whose type of Attributes TLV is Multi States Multiplexing Hierarchy Sub-TLV, The interim node checks the local data plane capability to see if this kind of multi stages multiplexing/demultiplexing hierarchy is acceptable on specific interface. As there is an acceptable kind of multi stages multiplexing/demultiplexing, it must determin an ODUk tunnel must be created between a pair of boundary node. The kind of multi stages multiplexing/demultiplexing hierarchy must be configed into the data plane.

5.  Security Considerations

TBD

6.  IANA Considerations

TBD

7.  References

7.1. Normative References

7.2. Informative References

Authors' Addresses