CCAMP Working Group G. Bernstein (ed.) Internet Draft Grotto Networking Updates: RFC 3946 D. Caviglia Category: Standards Track Ericsson Expires:
June 2009January 2010 R. Rabbat Google H. van Helvoort Huawei December 18, 2008July 29, 2009 Operating Virtual Concatenation (VCAT) and the Link Capacity Adjustment Scheme (LCAS) with Generalized Multi-Protocol Label Switching (GMPLS) draft-ietf-ccamp-gmpls-vcat-lcas-07.txtdraft-ietf-ccamp-gmpls-vcat-lcas-08.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." 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Abstract This document describes requirements for, and use of, the Generalized Multi-Protocol Label Switching (GMPLS) control plane in conjunction with the Virtual Concatenation (VCAT) layer 1 inverse multiplexing mechanism and its companion Link Capacity Adjustment Scheme (LCAS) which can be used for hitless dynamic resizing of the inverse multiplex group. These techniques apply to Optical Transport Network (OTN), Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), and Plesiochronous Digital Hierarchy (PDH) signals. 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]. Table of Contents 1. Introduction...................................................3 2. Revision History...............................................4 2.1. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-07..........4 2.2. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-05 and -06..4 220.127.116.11. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-04..........4 18.104.22.168. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-03..........4 22.214.171.124. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-02..........4 126.96.36.199. Changes from draft-ieft-ccamp-gmpls-vcat-lcas-01..........4 188.8.131.52. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-00..........5 3. VCAT/LCAS Scenarios and Specific Requirements..................5 3.1. VCAT/LCAS Interface Capabilities..........................5 3.2. Member Signal Configuration Scenarios.....................5Scenarios.....................6 3.3. VCAT Operation With or Without LCAS.......................6 3.4. VCGs and VCG Members......................................7 4. GMPLS Mechanisms in Support of VCGs............................7 4.1. VCGs Composed of a Single Co-Signaled Member Set..........8 4.1.1. One-shot VCG Setup with Co-Signaled Members..........8Members..........9 4.1.2. Incremental VCG Setup with Co-Signaled Members.......9 4.1.3. Procedure for VCG Reduction by Removing a Member.....9Member....10 4.1.4. Removing Multiple VCG Members in One Shot...........10 4.1.5. Teardown of Whole VCG...............................10 4.2. VCGs Composed of Multiple Co-Signaled Member Sets........10 4.2.1. Signaled VCG Layer Information......................11 4.3. Use of the CALL_ATTRIBUTES Object........................12 4.4. VCAT CALL_ATTRIBUTES TLV Object..........................12 4.5. Procedures for Multiple Co-signaled Member Sets..........13 4.5.1. Setting up a VCAT call and VCG......................15 4.5.2. Setting up a VCAT call + LSPs with no VCG...........15 4.5.3. Associating an existing VCAT call with a VCG........15 4.5.4. Removing the association between a call and VCG.....16 5. Error Conditions and Codes....................................16 6. IANA Considerations...........................................16 7. Security Considerations.......................................17 8. Contributors..................................................17Contributors..................................................18 9. Acknowledgments...............................................17Acknowledgments...............................................18 10. References...................................................19 10.1. Normative References....................................19 10.2. Informative References..................................19 Author's Addresses...............................................20 Intellectual Property Statement..................................21 Disclaimer of Validity...........................................21 Acknowledgment...................................................21 1. Introduction The Generalized Multi-Protocol Label Switching (GMPLS) suite of protocols allows for the automated control of different switching technologies including Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), Optical Transport Network (OTN) and Plesiochronous Digital Hierarchy (PDH). This document describes extensions to RSVP-TE to support the Virtual Concatenation (VCAT) layer 1 inverse multiplexing mechanism that has been standardized for SONET, SDH, OTN and PDH technologies along with its companion Link Capacity Adjustment Scheme (LCAS). VCAT is a TDM oriented byte striping inverse multiplexing method that works with a wide range of existing and emerging TDM framed signals, including very high bit rate OTN and SDH/SONET signals. Other than member signal skew compensation this layer 1 inverse multiplexing mechanism adds minimal additional signal delay. VCAT enables the selection of an optimal signal bandwidth (size), extraction of bandwidth from a mesh network, and, when combined with LCAS, hitless dynamic resizing of bandwidth and fast graceful degradation in the presence of network faults. To take full advantage of VCAT/LCAS functionality extensions to GMPLS signaling are given that enable the setup of diversely routed circuits that are members of the same VCAT group. 2. Revision History 2.1. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-07 None. Needed to refresh the expired draft. 2.2. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-05 and -06 Used the CALL_ATTRIBUTES Object from [MLN-Ext] rather than defining a new CALL_DATA object. 184.108.40.206. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-04 Fixed text in section 4.1.3 on VCG Reduction to more accurately describe LCAS and non-LCAS cases. 220.127.116.11. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-03 Added requirements on pre-existing members. Slightly modified solution for member sharing to constrain calls to a maximum of one VCG. Introduced the CALL_DATA object. Detailed coding of new TLV for VCAT to be included in the CALL_DATA object. Modified and expanded procedures to deal with new requirements and modified solution methodology. Added a list of error conditions. 18.104.22.168. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-02 Grammar and punctuation fixes. Updated references with newly published RFCs. 22.214.171.124. Changes from draft-ieft-ccamp-gmpls-vcat-lcas-01 Changed section 3.1 from "Multiple VCAT Groups per GMPLS endpoint" to "VCAT/LCAS Interface Capability" to improve clarity. Changed terminology from "component" signal to "member" signal where possible (not quoted text) to avoid confusion with link bundle components. Added "Dynamic, member sharing" scenario. Clarified requirements with respect to scenarios and the LCAS and non-LCAS cases. Added text describing needed signaling information between the VCAT endpoints to support required scenarios. Added text to describe: co-signaled, co-routed, data plane LSP, control plane LSP and their relationship to the VCAT/LCAS application. Change implementation mechanism from one based on the Association object to one based on "Call concepts" utilizing the Notify message. 126.96.36.199. Changes from draft-ietf-ccamp-gmpls-vcat-lcas-00 Updated reference from RFC3946bis to issued RFC4606 Updated section 3.2 based on discussions on the mailing list 3. VCAT/LCAS Scenarios and Specific Requirements There are a number of specific requirements for the support of VCAT/LCAS in GMPLS that can be derived from the carriers' application-specific demands for the use of VCAT/LCAS and from the flexible nature of VCAT/LCAS. These are set out in the following section. 3.1. VCAT/LCAS Interface Capabilities In general, an LSR can be ingress/egress of one or more VCAT groups. VCAT and LCAS are interface capabilities. An LSR may have, for example, VCAT-capable interfaces that are not LCAS-capable. It may at the same time have interfaces that are neither VCAT nor LCAS- capable. 3.2. Member Signal Configuration Scenarios We list in this section the different scenarios. Here we use the term "VCG" to refer to the entire VCAT group and the terminology "set" and "subset" to refer to the collection of potential VCAT group member signals. Fixed, co-routed: A fixed bandwidth VCG, transported over a co-routed set of member signals. This is the case where the intended bandwidth of the VCG does not change and all member signals follow the same route to minimize differential delay. The intent here is the capability to allocate an amount of bandwidth close to that required at the client layer. Fixed, diversely routed: A fixed bandwidth VCG, transported over at least two diversely routed subsets of member signals. In this case, the subsets are link-disjoint over at least one link of the route. The intent here is more efficient use of network resources, e.g., no unique route has the required bandwidth. Fixed, member sharing: A fixed bandwidth VCG, transported over a set of member signals that are allocated from a common pool of available member signals without requiring member connection teardown and setup. Dynamic, co-routed: A dynamic VCG (bandwidth can be increased or decreased via the addition or removal of member signals), transported over a co-routed set of members. The intent here is dynamic resizing and resilience of bandwidth. Dynamic, diversely routed: A dynamic VCG (bandwidth can be increased or decreased via the addition or removal of member signals), transported over at least two diversely routed subsets of member signals. The intent here is efficient use of network resources, dynamic resizing and resilience of bandwidth. Dynamic, member sharing: A dynamic bandwidth VCG, transported over a set of member signals that are allocated from a common pool of available member signals without requiring member connection teardown and setup. 3.3. VCAT Operation With or Without LCAS VCAT capabilities may be present with or without the presence of LCAS. The use of LCAS is beneficial to the provision of services, but in the absence of LCAS, VCAT is still a valid technique. Therefore GMPLS mechanisms for the operation of VCAT are REQUIRED for both the case where LCAS is available and the case where it is not available. The GMPLS procedures for the two cases SHOULD be identical. GMPLS signaling for LCAS-capable interfaces MUST support all scenarios of section 3.2. with no loss of traffic. GMPLS signaling for non-LCAS-capable interfaces MUST support only the "fixed" scenarios of section 3.2. To provide for these requirements GMPLS signaling MUST carry the following information on behalf of the VCAT endpoints: The type of the member signal that the VCG will contain, e.g., VC-3, VC-4, etc. The total number of members to be in the VCG. This provides the endpoints in both the LCAS and non-LCAS case with information on which to accept or reject the request, and in the non-LCAS case will let the receiving endpoint know when all members of the VCG have been established. Identification of the VCG and its associated members. This provides information that allows the endpoints to differentiate multiple VCGs and to tell what members (LSPs) to associate with a particular VCG. 3.4. VCGs and VCG Members VCG members (server layer connections) may be set up prior to their use in a VCG. VCG members (server layer connections) may exist after their corresponding VCG has been removed. The signaling solution SHOULD provide a mechanism to support the previous scenarios. However, it is not required that arbitrarily created server layer connections be supported in the above scenarios. 4. GMPLS Mechanisms in Support of VCGs We describe in this section the signaling mechanisms that already exist in GMPLS using RSVP-TE [RFC3473] and [RFC4328], and the extensions needed to completely support the requirements of section 3. When utilizing GMPLS with VCAT/LCAS we utilize a number of control and data plane concepts that we describe below. VCG member -- This is an individual data plane signal of one of the permitted SDH, SONET, OTN or PDH signal types. Co-signaled member set -- One or more VCG members (or potential members) set up via the same control plane signaling exchange. Note that all members in a co-signaled set follow the same route. Co-routed member set - One or more VCG members that follow the same route. Although VCG members may follow the same path, this does not imply that they were co-signaled. Data plane LSP -- for our purposes here, this is equivalent to an individual VCG member. Control plane LSP -- A control plane entity that can control multiple data plane LSPs. For our purposes here this is equivalent to our co-signaled member set. Section 4.1 is included for informational purposes only. It describes existing GMPLS procedures that support a single VCG composed of a single co-signaled member set. Section 4.2 describes new procedures to support VCGs composed of more than one co-signaled member sets. This includes the important application of a VCG composed of diversely routed members. Where possible it reuses applicable existing procedures from section 4.1. 4.1. VCGs Composed of a Single Co-Signaled Member Set Note that this section is for informational purposes only. The existing GMPLS signaling protocols support a VCG composed of a single co-signaled member set. Setup using the NVC field is explained in section 2.1 of [RFC4606]. In this case, one (single) control plane LSP is used in support of the VCG. There are two options for setting up the VCG, depending on hardware capability, or management preferences: one-shot setup and incremental setup. The following sections explain the procedure based on an example of setting up a VC-4-7v SDH VCAT group (corresponding to an STS-3c-7v SONET VCAT group). 4.1.1. One-shot VCG Setup with Co-Signaled Members An RSVP-TE Path message is used with the following parameters. With regards to the traffic parameters, the elementary signal is chosen (6 for VC-4/STS-3c_SPE). The value of NVC is then set to 7. A Multiplier Transform greater than 1 (say N>1) is used if the operator wants to set up N VCAT groups that will belong to, and be assigned to, one LSP. SDH or SONET labels in turn have to be assigned for each member of the VCG and concatenated to form a single Generalized Label constructed as an ordered list of 32-bit timeslot identifiers of the same format as TDM labels. [RFC4606] requires that the order of the labels reflect the order of the payloads to concatenate, and not the physical order of time-slots. 4.1.2. Incremental VCG Setup with Co-Signaled Members In some cases, it may be necessary or desirable to set up the VCG members individually, or to add group members to an existing group. One example of this need is when the hardware that supports VCAT can only add VCAT elements one at a time or cannot automatically match the elements at the ingress and egress for the purposes of inverse multiplexing. Serial or incremental setup solves this problem. In order to accomplish incremental setup an iterative process is used to add group members. For each iteration, NVC is incremented up to the final value required. The iteration consists of the successful completion of Path and Resv signaling. At first, NVC = 1 and the label includes just one timeslot identifier At each of the next iterations, NVC is set to (NVC +1), one more timeslot identifier is added to the ordered list in the Generalized Label (in the Path or Resv message). A node that receives a Path message that contains changed fields will process the full Path message and, based on the new value of NVC, it will add a component signal to the VCAT group, and switch the new timeslot based on the new label information. Following the addition of the new label to the LSP, LCAS may be used in-band to add the new label into the existing VCAT group. LCAS signaling for this function is described in [ITU-T-G.7042]. 4.1.3. Procedure for VCG Reduction by Removing a Member The procedure to remove a component signal is similar to that used to add components as described in Section 4.1.2. The LCAS in-band signaling step is taken first to take the component out of service from the group. LCAS signaling is described in [ITU-T-G.7042]. In this case, the NVC value is decremented by 1 and the timeslot identifier for the dropped component is removed from the ordered list in the Generalized Label. Note that for interfaces that are not LCAS-capable, removing one component of the VCG will result in errors in the inverse- multiplexing procedure of VCAT and result in the teardown of the whole group. So, this is a feature that only LCAS-capable VCAT interfaces can support without management intervention at the end points. Note also that a VCG member can be temporary removed from the VCG due to a failure of the component signal. The LCAS in-band signaling will take appropriate actions to adjust the VCG as described in [ITU-T- G.7042]. 4.1.4. Removing Multiple VCG Members in One Shot The procedure is similar to 4.1.3. In this case, the NVC value is changed to the new value and all relevant timeslot identifiers for the components to be torn down are removed from the ordered list in the Generalized Label. This procedure is also not supported for VCAT-only interfaces without management intervention as removing one or more components of the VCG will tear down the whole group. 4.1.5. Teardown of Whole VCG The entire LSP is deleted in a single step (i.e., all components are removed in one go) using deletion procedures of [RFC3473]. 4.2. VCGs Composed of Multiple Co-Signaled Member Sets The motivation for VCGs composed of multiple co-signaled member sets comes from the requirement to support VCGs with diversely routed members. The initial GMPLS specification did not support diversely routed signals using the NVC construct. In fact, [RFC4606] says: [...] The standard definition for virtual concatenation allows each virtual concatenation components to travel over diverse paths. Within GMPLS, virtual concatenation components must travel over the same (component) link if they are part of the same LSP. This is due to the way that labels are bound to a (component) link. Note however, that the routing of components on different paths is indeed equivalent to establishing different LSPs, each one having its own route. Several LSPs can be initiated and terminated between the same nodes and their corresponding components can then be associated together (i.e., virtually concatenated). The setup of diversely routed VCG members requires multiple co- signaled VCG member sets, i.e., multiple control plane LSPs. To support a VCG with multiple co-signaled VCG members sets requires being able to identify separate control plane LSPs with a single VCG and exchange information pertaining to the VCG as a whole. This is very similar to the "Call" concept described in [RFC4974]. We can think of our VCAT/LCAS connection, e.g., our VCG, as a higher layer service that makes use of multiple lower layer (server) connections that are controlled by one or more control plane LSPs. 4.2.1. Signaled VCG Layer Information When a VCG is composed of multiple co-signaled member sets, none of the control plane LSP's signaling information can contain information pertinent to the entire VCG. In this section we give a list of information that should be communicated at what we define as the VCG Call layer, i.e., between the VCG signaling endpoints. To accommodate this information additional objects or TLVs are incorporated into the Notify message as it is described for use in call signaling in [RFC4974]. VCG Call setup information signaled via the Notify message with the Call management bit (C-bit) set: 1. Signal Type 2. Number of VCG Members 3. LCAS requirements: a. LCAS required b. LCAS desired c. LCAS not desired (but acceptable) 4. VCG Identifier - Used to identify a particular VCG separately from the call ID so that call members can be reused with different VCGs per the requirements for member sharing and the requirements of section 3.4. 4.3. Use of the CALL_ATTRIBUTES Object In RFC4974 the general mechanism for communicating call information via Notify messages is given. In [MLN-Ext] the CALL_ATTRIBUTES object is introduce for the conveyance of call related information during call establishment and updates. We define a new 4.4. VCAT CALL_ATTRIBUTES TLV Object For use in the CALL_ATTRIBUTES object in Notify messages we define the following VCAT related 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 = TBD | Length = 12 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Signal Type | Number of Members | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LCAS Req | Action | VCG ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Where Type is TBD, and the Length = 12 bytes. Signal Type can take the following values and MUST never change over the lifetime of a VCG: Value Type (Elementary Signal) ----- ------------------------ 1 VT1.5 SPE / VC-11 2 VT2 SPE / VC-12 3 STS-1 SPE / VC-3 4 STS-3c SPE / VC-4 11 OPU1 (i.e., 2.5 Gbit/s 12 OPU2 (i.e., 10 Gbit/s) 13 OPU3 (i.e., 40 Gbit/s) 21 T1 (i.e., 1.544 Mbps) 22 E1 (i.e., 2.048 Mbps) 23 E3 (i.e., 34.368 Mbps) 24 T3 (i.e., 44.736 Mbps) Number of Members is a non-negative integer that indicates the total number of members in the VCG (not just the call)and MUST be changed over the life of the VCG to indicate the current number of members. LCAS Required can take the following values and MUST NOT change over the life of a VCG: Value Meaning ----- --------------------------------- 0 LCAS required 1 LCAS desired 2 LCAS not desired (but acceptable) Action is used to indicate the relationship between the call and the VCG and takes the following values. Value Meaning ----- --------------------------------- 0 No VCG ID (set up call prior to VCG creation) 1 New VCG for Call 2 No Change in VCG ID (number of members may have changed) 3 Remove VCG from Call VCG ID: A 16 bit non-negative integer used to identify a particular VCG within a session. This number MUST NOT change over the lifetime of a VCG but can change over the lifetime of a call. To support the member sharing scenario of section 3.2. and the requirements of section 3.4. we allow the VCG Identifier within a call to be changed. In this way the connections associated with a call can be dedicated to a new VCG (allowing for a priori connection establishment and connection persistence after a VCG has been removed). 4.5. Procedures for Multiple Co-signaled Member Sets To establish a VCG a CALL_ATTRIBUTES object containing a VCAT TLV is exchanged as part of call establishment or update. A VCG can be established at the same time as a new call or associated with an existing call that currently has no VCG association. When modifying the bandwidth of a VCG a CALL_ATTRIBUTES object containing a VCAT TLV MUST precede any of those changes and indicate the new total number of VCG members. The following mechanisms can be used to increase the bandwidth of a VCG. LSPs are added to a VCAT Call associated with a VCG (Action = 2). A VCG is associated with an existing VCAT call containing LSPs (Action = 1). The following internal ordering is used when increasing the bandwidth of a VCG in a hitless fashion when LCAS is supported: A CALL_ATTRIBUTES Object containing a VCAT TLV indicating the new number of members after the proposed increase is sent. If an error is returned from the receiver the VCG state remains the same prior to the attempted increase. Either: (a) New LSPs are set up within a call associated with the VCG, or (b) LSPs in an existing call are now associated with the VCG. The internal LCAS entity is instructed by the endpoints to "activate" the new VCG member(s). The following mechanisms can be used to decrease the bandwidth of a VCG. LSPs are removed from a VCAT Call associated with a VCG (Action = 2). A VCG association is removed from existing VCAT call containing LSPs (Action = 3). In general the following internal ordering is used when decreasing the bandwidth of a VCG in a hitless fashion when LCAS is supported: 1. A CALL_ATTRIBUTES Object containing a VCAT TLV indicating the new number of members after the proposed decrease is sent. If an error is returned from the receiver the VCG state remains the same prior to the attempted decrease. 2. The LCAS entity is instructed by the endpoints to "deactivate" the members to be removed from the VCG. 3. Either: (a) An LSP is removed from a call associated with a VCG; or (b) All the LSPs of a call are removed from the VCG when the association between the VCG and VCAT call is removed. Note that when LCAS is not used or unavailable the VCG will be in an unknown state between the time the VCG call level information is updated and the actual data plane LSPs are added or removed. Note that the incremental setup procedure of section 4.1.2. can be applied to any of the above procedures. 4.5.1. Setting up a VCAT call and VCG Arguably the most common operation will be simultaneously setting up a VCAT call and its associated VCG at the same time. To do this when one sets up a new VCAT call in the VCAT TLV one sets Action = 1 indicating that this is a new VCG for this call. LSPs would then be added to the call until the number of members reaches the number specified in the VCAT TLV. Note that any other bandwidth modifications to the VCG whether up or down will require a new VCAT call message with an appropriately modified TLV reflecting the new number of members. 4.5.2. Setting up a VCAT call + LSPs with no VCG To provide for pre-establishment of the server layer connections for a VCG one can establish a VCAT call without an associated VCG. In addition, to provide for member sharing a pool of calls with connections can be established, then one or more of these calls (with accompanying connections) can be associated with a particular VCG (via the VCG ID). Note that multiple calls can be associated with a single VCG but that no call contains members used in more than one VCG. To establish a VCAT call with no VCG association when one sets up a new VCAT call in the VCAT TLV one sets Action = 0 indicating that this is a VCAT call without an associated VCG. LSPs can then be added to the call. The number of members parameter in the VCAT TLV has no meaning at this point since it reflects the intended number of members in a VCG and not in a call. A call will know via the containment hierarchy about its associated data plane LSPs. However, the signal type does matter since signal types can never be mixed in a VCG and hence a VCAT call should only contain one signal type. 4.5.3. Associating an existing VCAT call with a VCG Given a VCAT call without an associated VCG such as that set up in section 4.5.2. one associates it with a VCG as follows. In the VCAT call a new notify message is sent with a CALL_ATTRIBUTES object with a VCAT TLV with Action = 1, a VCG ID, and the correct number of VCG members specified based on adding all of the calls data plane LSPs to the VCG as members. Note that the total number of VCGs supported by a piece of equipment may be limited and hence on reception of any message with a change of VCG ID this limit should be checked. Likewise the sender of a message with a change in VCG ID should be prepared to receive an error response. To take a particular VCG out of service, rather than just removing all its member, a special flag element is included. 4.5.4. Removing the association between a call and VCG To reuse the server layer connections in a call in another VCG one first needs to remove the current association between the call and a VCG. To do this, in the VCAT call a new notify message is sent with a CALL_ATTRIBUTES object with a VCAT TLV with Action = 3, a VCG ID, and the correct number of VCG members specified based on removing all of the calls data plane LSPs from the VCG as members. When the association between a VCG and all existing calls has been removed then the VCG is considered torn down. 5. Error Conditions and Codes VCAT Call and member LSP setup can be denied for various reasons. Below is a list of error conditions that can be encountered during these procedures. These fall under RSVP error code TBD. These can occur when setting up a VCAT call or associating a VCG with a VCAT call. Error Subcode ------------------------------------ -------- VCG signal type not Supported 1 LCAS option not supported 2 Max number of VCGs exceeded 3 Max number of VCG members exceeded 4 LSP Type incompatible with VCAT call 5 6. IANA Considerations This document requests from IANA the assignment of a new TLV for the CALL_ATTRIBUTES Object from [MLN-Ext]. Within this VCAT TLV are a set of code points for permissible signal types. In addition, we request a new RSVP error code for use with VCAT call and define a number of corresponding error sub-codes. 7. Security Considerations This document introduces a specific use of the Notify message and admin status object for GMPLS signaling as originally specified in [RFC4974]. It does not introduce any new signaling messages, nor change the relationship between LSRs that are adjacent in the control plane. The call information associated with diversely routed control plane LSPs, in the event of an interception may indicate that there are members of the same VCAT group that take a different route and may indicate to an interceptor that the VCG call desires increased reliability. Otherwise, this document does not introduce any additional security considerations. 8. Contributors Wataru Imajuku (NTT) 1-1 Hikari-no-oka Yokosuka Kanagawa 239-0847 Japan Phone +81-46-859-4315 Email: firstname.lastname@example.org Julien Meuric France Telecom 2, avenue Pierre Marzin 22307 Lannion Cedex France Phone: + 33 2 96 05 28 28 Email: email@example.com Lyndon Ong Ciena PO Box 308 Cupertino, CA 95015 United States of America Phone: +1 408 705 2978 Email: firstname.lastname@example.org 9. Acknowledgments The authors would like to thank Adrian Farrel, Maarten Vissers, Trevor Wilson, Evelyne Roch, Vijay Pandian, Fred Gruman, Dan Li, Stephen Shew, Jonathan Saddler and Dieter Beller for extensive reviews and contributions to this draft. 10. References 10.1. Normative References [MLN-Ext] Papadimitriou, D., Vigoureux M., Shiomoto, K. Brungard, D., Le Roux, JL., "Generalized Multi- Protocol Label Switching (GMPLS) Protocol Extensions for Multi-Layer and Multi-Region Networks (MLN/MRN)", work in progress: draft-ietf-ccamp-gmpls-mln- extensions-03.txt, October, 2008. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC4328] Papadimitriou, D., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Extensions for G.709 Optical Transport Networks Control", RFC 4328, January 2006. [RFC4606] Mannie, E. and D. Papadimitriou, "Generalized Multi- Protocol Label Switching (GMPLS) Extensions for Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH) Control", RFC 4606, December 2005. [RFC4974] Papadimitriou, D. and A. Farrel, "Generalized MPLS (GMPLS) RSVP-TE Signaling Extensions in Support of Calls", RFC 4974, August 2007. 10.2. Informative References [ANSI-T1.105] American National Standards Institute, "Synchronous Optical Network (SONET) - Basic Description including Multiplex Structure, Rates, and Formats", ANSI T1.105- 2001, May 2001. [ITU-T-G.7042] International Telecommunications Union, "Link Capacity Adjustment Scheme (LCAS) for Virtual Concatenated Signals", ITU-T Recommendation G.7042, March 2006. [ITU-T-G.7043] International Telecommunications Union, "Virtual Concatenation of Plesiochronous Digital Hierarchy (PDH) Signals", ITU-T Recommendation G.7043, July 2004. [ITU-T-G.707] International Telecommunications Union, "Network Node Interface for the Synchronous Digital Hierarchy (SDH)", ITU-T Recommendation G.707, December 2003. [ITU-T-G.709] International Telecommunications Union, "Interfaces for the Optical Transport Network (OTN)", ITU-T Recommendation G.709, March 2003. Author's Addresses Greg M. Bernstein (ed.) Grotto Networking Fremont California, USA Phone: (510) 573-2237 Email: email@example.com Diego Caviglia Ericsson Via A. Negrone 1/A 16153 Genoa Italy Phone: +39 010 600 3736 Email: diego.caviglia@(marconi.com, ericsson.com) Richard Rabbat Google, Inc. 1600 Amphitheatre Parkway Mountain View, CA 94043, USA Email: firstname.lastname@example.org Huub van Helvoort Huawei Technologies, Ltd. 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