Generalized Switch Management Protocol (gsmp) Georg Kullgren Internet Draft Steven Shew Document: draft-ietf-gsmp-reqs-02.txt Nortel Networks Category: Standards Track Hormuzd Khosravi Expiration Date: December 2002 Intel Jonathan Sadler Tellabs Satoru Okamoto Kohei Shiomoto Atsushi Watanabe NTT June 2002 Requirements For Adding Optical Support To GSMPv3 draft-ietf-gsmp-reqs-02.txt 1. Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026 except that the right to produce derivative works is not granted. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html 2. Abstract This memo provides an overview of additional requirements on the GSMP protocol. 3. Changes Merged Sections 2 and 4. Kullgren, et. al. GSMP WG - June 2002 1 draft-ietf-gsmp-reqs-02.txt December 2002 Moved Link Bundling out of GSMP scope as links are network in scope, and not node in scope. Where appropriate, changed text that was specific to transparent optical switching generic so it also applies to SONET/SDH switching. Updated references to current CCAMP Drafts/GSMP RFCs. Took out references that were not referred to by the base text. 4. Table of Contents 5. Overview This document details the changes to GSMP necessary for the support of optical (non-transparent and all optical), SONET/SDH, and spatial switching of IP packets, L2 frames and TDM data. When implemented, GSMP controllers will then be able to control: photonic cross- connects (optical-optical), transparent optical cross connects (optical-electrical-optical, frame independent), opaque cross connects (optical-electrical-optical, SONET/SDH frames), and traditional TDM switches (all electrical). The resulting systems could form IP based optical routers, optical label switches, wavelength routers, and dynamic optical cross connects. Several different generic models exist defining how to provide control plane functionality in an optical network [1][2][3]. This document takes no position on which model is most appropriate (e.g., single or multiple routing plane instances). The only assumption is that the ability to separate the control mechanisms from the data switching is as useful for the signaling of optical paths (e.g., GMPLS) as it is for the signaling of L2 paths (e.g., MPLS). Therefore, the requirements contained within are focused only on the separation of control functions from data functions in order to provide a more flexible network architecture. GSMPv3[4] is well suited for providing the control interface necessary for allowing an IP based controller to direct the activities of an optical switch. In order for GSMP to operate between controllers and optical switches and cross connects, support for optical labels and service and resource abstractions must be added to GSMP. 6. Requirements for Optical Support 6.1. Label 6.1.1. Label Types New labels are needed to identify the entities that are to be switched in the optical fabric. These are longer than the labels defined in GSMPv3 as they have physical and structural context. As Kullgren, et. al. GSMP WG - June 2002 2 draft-ietf-gsmp-reqs-02.txt December 2002 GMPLS[1][2] has had very similar requirements for label formats alignment with GMPLS is proposed. This includes support for: - Digital Carrier Hierarchy (e.g., DS-1, E1) - SONET and SDH Hierarchy (e.g., OC-3, STM-1, VT1.5, VC-12) - PDH labels [5] - OTN G.709 labels - Lambdas - Fibers GSMP MUST include support for all label types as well as for label hierarchies and label lists as defined by GMPLS. Therefore the ability to perform operations on groups of the above labels MUST also be supported (e.g., 5 OC-3s, contiguous wavebands) 6.1.2. Label Management Issues An updated label range message MUST be provided. There MUST also be support of multiplexing (e.g. no multiplexing, SONET, Gigabit Ethernet multiplexing etc). 6.2. Statistics messages Optical switches have a number of different statistics which are not in common with ATM, or Frame Relay switches. Consequently, the statistics messages SHOULD be updated to report Performance Monitoring statistics defined for all new optical transport technologies added to GSMP. 6.3. Configuration Issues 6.3.1. Switch Configuration 6.3.1.1. Layer Switching Identification Since an Optical Switches may be able to provide connection services at multiple transport layers (i.e. STS-3c, STS-1, VT-1.5, DS3, DS1), and not all switches are expected to support the same transport layers, the switch will need to notify the controller of the specific layers it can support. Therefore, the Switch Configuration message MUST be extended to provide a list of the transport layers for which an optical switch can perform switching. Kullgren, et. al. GSMP WG - June 2002 3 draft-ietf-gsmp-reqs-02.txt December 2002 6.3.2. Port Configuration The port configuration message supplies the controller with the configuration information related to a single port. Consequently, extensive additions will need to be made to this command. 6.3.2.1. Port Type extensions Port types MUST be added to support the mix of optical signals that can operate over a single fiber. The port information that MAY need to be conveyed includes[6]: - wavelengths available per interface - bit rate per wavelength - type of fiber 6.3.2.2. Supported Signal Type extensions Since a port on an optical switch may support signals at multiple transport layers, it is necessary to understand the signals supported, as well as the possible ways that one signal can be transported within another. For OTN, SONET/SDH and PDH optical switches, the Port configuration message MUST be extended to detail the different transport layer signals that are supported by a port. Furthermore, this extension MUST detail which signals may be transported by another signal. This mechanism MUST also provide information about optional capabilities (such as virtual concatenation and arbitrary concatenation for SONET/SDH) available on a port. 6.3.2.3. Trace Mechanism support Identification A number of transport layer signals include overhead channels that can be used to identify the source of a signal. Since they are embedded in the signal, only the network element has access to the signals. However, not all network elements have the capability to set or read the messages in these channels on every port. Consequently, this port attribute needs to be reported to the controller. The Port Configuration message MUST be extended to report which trace mechanisms are supported by a port. 6.3.2.4. Port Location Identification Since contemporary Optical switches have the ability to support tens of thousands of ports in hundreds of shelves located in as potentially as many bays, the current "Slot/Port" location identifier is inadequate. Kullgren, et. al. GSMP WG - June 2002 4 draft-ietf-gsmp-reqs-02.txt December 2002 The Slot/Port Location Identifier MUST be extended to encode Bay/Shelf/Slot/Port. 6.3.2.5. Port-related Partitioning Extensions Partitioning can be done for any resource that exists in the network element. The GSMP partitioning draft currently defines ports and switching resources as partitionable resources. Since optical switches may support multiple transport network layers, an additional resource type is introduced: the transport layer signal. The point where a transport layer signal is inserted into a lower layer signal (called an "access point" by the ITU[7]), is very similar to a port. Therefore, when partitioning is done on a transport layer signal basis, the partition that is the user of the access point MUST have a port that associated with the access point. Labels will then be used in the to describe the subordinate signals. 6.3.3. Service Configuration While new capability sets MUST be added to support quality parameters in optical switches, no changes are foreseen to the service configuration message as its role to carry the service information as defined in the applicable service model. 6.4. Service Model Issues While one assumption of using optical media is that bandwidth is plentiful, it should be expected that traffic engineering will be necessary in any case[4]. GSMP provides the means for each connection to be created with specific attributes. Therefore, service parameters will need to be defined for each of the Different Optical technologies. 6.4.1 Transparent Optical Capability to control re-timing and re-shaping on a per port level MUST be added. 6.4.2 SONET/SDH and OTN The capability to control the adaptation parameters used when a transport signal is inserted into another transport signal MUST be added. These parameters SHOULD be modifiable at times other than adding a branch so that functions such as Tandem Connection Monitoring can be configured.Currently, the default set of service models in GSMP are all based on the services models defined elsewhere, e.g. the Intserv model[8][9], the Diffserv[10] model, ATM QoS models and the Frame relay forum QoS models. A determination needs to be made of the applicable service models for optical Kullgren, et. al. GSMP WG - June 2002 5 draft-ietf-gsmp-reqs-02.txt December 2002 channel trails. These models MUST then be mapped to the GSMP capability set mechanism. 6.5. Encapsulation issues The working group needs to decide whether a new encapsulation is required. In other words, will all optical switches used in either the MPLS over Optics and the IP over optics applications require that IP be implemented on the control channel connecting the GSMP controller and Optical switch (the GSMP target). A new encapsulation SHOULD be defined allowing the use of a non-IP raw wavelength control connection. Likewise, a new encapsulation SHOULD be defined allowing GSMP to be used in legacy DCN environments that use OSI CLNP. 6.6. MIB Issues If a new encapsulation is defined, then the encapsulation group SHOULD be updated. No other changes should be required. 6.7. OXC Transaction Model 6.7.1 Serial Transactions Many existing OXCs use a command interface which assumes a serial transaction model. That is, a new command cannot be issued or processed until the existing command is completed. Under provisioning control via a network management application, and with non-dynamic path setup, this model has been adequate. Moving to a dynamic path setup capability with a distributed control plane, a parallel transaction model is likely required for performance. This is particularly helpful when the performance of setting up a TDM style connection is much slower than setting up an L2 connection table. If the OXC is not able to support a parallel transaction model, a GSMP controller MUST be informed of this and adopt serial transaction behavior. 6.7.2. Bulk Transactions Again due to the time it may take some OXCs to setup TDM connections relative to L2 fabrics (e.g., VC-4/STS-1 SPE fabric in an HOVC/STS switch), support for sending multiple transactions in the same message is a useful optimization. When an OXC receives a bulk message, the individual transactions are acted upon and a single reply is sent. If parallel transactions are not supported, bulk messages can improve performance by reducing transaction overhead. Bulk transactions SHOULD be supported. Kullgren, et. al. GSMP WG - June 2002 6 draft-ietf-gsmp-reqs-02.txt December 2002 6.8. OXC Restoration Capabilities To achieve fast link protection performance (e.g., 50 ms after failure detection), SONET/SDH and some OXC systems use hardware based protection schemes (e.g., ring protection). Achieving this level of performance solely using a data control plane such as GMPLS is a serious challenge. An alternate approach is to utilize fast restoration capabilities of an OXC with a dynamic control plane. An implication of this hybrid approach is that extensions are needed to GSMP to provision the behavior of an OXC in anticipation of a link failure. This differs from the strict master-slave relationship in GSMP for Layer 2 switches in that here the OXC is capable of taking an action independent of the GSMP controller and then informing the controller afterwards. Consequently, the GSMP port configuration command MUST be extended to allow autonomous protection behaviors to be provisioned into the Network Element. Furthermore, the controller MUST be able to provide the parameters for when reversion from a backup link to the original link is allowed. This may take form of hold-off timers, BER parameters, or the requirement for controller directed reversion. 6.8.1. Non-Reserved Protection Links An example of protection OXC behavior is that when a link fails, a backup link may be used to protect traffic on. This backup link could be selected from a set of links, none of which are pre- reserved. A backup link could be shared with one or more "working" links which is a form of 1:n shared protection. Specifying the set of possible backup links SHOULD be done as an option to the Add- Branch message. When a backup link is used or the OXC reverts back to the original link, the control plane (i.e., signaling) may need to know about the new path state in order to notify the operator, or take some other OAM action (e.g., billing, SLA monitoring). An additional GSMP message to inform the controller SHOULD be added to do this. 6.8.2. Dedicated Protection Links A more specialized form of restoration called "1+1" defines a (usually node disjoint) protection path in a transport/optical network for a given working path. At the ingress node to the path, the traffic signal is sent simultaneously along both working and protection paths. Under non-failure conditions at the egress node, only the last link of the working path is connected to the client. When any link in the working path fails, traffic on the working path Kullgren, et. al. GSMP WG - June 2002 7 draft-ietf-gsmp-reqs-02.txt December 2002 ceases to be received at end of the path. The egress OXC detects this condition and then switches to use the last link of the protection path without the controller having to issue a Move-Input- Branch message. At no time is the ingress node aware which link the egress node is using. Selection of the protection path and all of its links is outside the scope of GSMP. Specification of the two output branches at the ingress node can be done with the usual Add-Branch semantics. The ingress node protection link is not shared with any other working link. Specification of the two input branches at the egress node should be done when the Add-Branch message is sent. This SHOULD be an option to that message. The egress node protection link is not shared with any other working link. When a protection link is used or the OXC reverts back to the working link, the control plane (i.e., signaling) may need to know about the new path state in order to notify the operator, or take some other OAM action (e.g., billing, SLA monitoring). An additional GSMP message to inform the controller SHOULD be added to do this. If an alternate input port is not specified with an original Add- Branch message, it MAY be specified in a subsequent Add-Branch message. In this case, it is useful to include information about existing users of the output port in that Add-Branch message. This helps the OXC immediately learn of the association between the new input port and an existing one. The association is used to enable OXC protection procedures. This capability MUST be added to the add- branch message. Similar contextual information is needed for a Delete-Branch message so that the OXC can determine if a path becomes unprotected. This capability MUST be added to the Delete-branch message. 6.8.3. Protection Triggers Aside from link or equipment failures, there are a variety of maintenance conditions that could cause the backup/protection link(s) to be used. These may include: - Scheduled maintenance of the working link. Here the network operator deliberately takes a link out of service to perform maintenance. - Reconfiguration of fiber/node/network which causes temporary need to use backup links. It may be useful to specify these triggers when the backup/protection links are defined with the Add-Branch message. This depends on how the OXC is implemented to be aware of such triggers. This is for further study. Kullgren, et. al. GSMP WG - June 2002 8 draft-ietf-gsmp-reqs-02.txt December 2002 6.8.4. Protection Link Capabilities When an OXC has the capability to perform protection switching independently from the OCC, it may be useful for the OCC to be informed of these capabilities at switch and/or port configuration. Applications in the GSMP controller could use this information. For example, signaling clients could define a path protection scheme over multiple GSMP enabled OXCs. This is for further study. 6.9. Controller directed restoration Bi-directional Connection Replacement Connections in the transport network are inherently point-to-point bi-directional. Unfortunately, GSMPv3 currently does not allow for the B and R flags to be set on a add branch message. This means that it is not possible to do an atomic replacement of a bi- directional connection -- an action that is desirable for controller directed restoration. Consequently, the protocol MUST be changed to allow these flags to be used at the same time. 6.10 GSMP support for optical cross-connect system The cross-connect system such as photonic cross-connect, transparent optical cross-connect, opaque cross-connect and traditional TDM switch can be consist of not only cross-connect (/switch) function, but also multiplexing function (including transmission function), path termination function (including client signal termination function). In the optical cross-connect (OXC) system, the multiplexing function corresponds to the wavelength division multiplexing (WDM). The optical regenerator and wavelength converter may be necessary in order to realize long-haul transmission and to use effectively the wavelength resource respectively. Figure 1 shows the generalized OXC functional block. The OXC system shown in Fig.1 should be controlled / managed by GSMP. The advantage of this concept is that the GSMP can control the OXC system, without other control protocols. This will reduce the cost and time of OXC control application development. To control the OXC system, the control concept of both connection termination and trail termination for each optical label switched path or WDM sections (defined in G.872; OMS and OTS) should be introduced in the GSMP. The GSMP for optical switch can be located as subset of that for optical cross-connect. Kullgren, et. al. GSMP WG - June 2002 9 draft-ietf-gsmp-reqs-02.txt December 2002 +-------------+-------------------+-----------+ -->| | | | WDM | Wavelength | Opt. regenerator/ | Opt. | signals | demultiplex/| Wavelength | switch | | multiplex | converter | | <--| | | | +-------------+-------------------+-----------+ || || Client +-----------+ signals (In) -->| Path | Client | terminator| signals(Out) <--| | +-----------+ Figure 1 General OXC functional block 7. Requirements from Implementors 7.1. GSMP Packet Format The Basic GSMP Message Format in chapter 3.1.1 in [5] describes the common fields present in all GSMP messages except for the Adjacency protocol. 7.1.1. Message segmentation If a message exceeds the MTU of the link layer it has to be segmented. This was originally done with the "More" value in the Result field. The addition of the I flag and the SubMessage Number to the header has made the "More" value in the Result field obsolete. A clarification of the I flag and SubMessage Number is also needed. 7.1.1.1. "More" Result Value The "More" value should not be used in GSMP. A request message with the Result field set to "More" SHOULD be answered with a failure response with a Code field indicating the type of failure. 7.1.1.2. SubMessage Number The definition of the SubMessage field should indicate if the submessages are numbered starting with 0 or 1. 7.1.1.3. I flag The value of the I flag for messages which are not segmented is unspecified. Kullgren, et. al. GSMP WG - June 2002 10 draft-ietf-gsmp-reqs-02.txt December 2002 7.1.1.4. Updated Messages The "Report Connection State Reply Message" and "All Ports Configuration Message" should be rewritten to use the I flag instead of the More flag. 7.1.1.5. Message Segmentation example A description of how to segment a message should be provided. The definition of the Length field should state if each segment should contain the total GSMP message length or the length of the segment. 7.1.2. Transaction Identifier The Transaction Identifier in [5] does not distinguish between replies from a request with "AckAll" and "NoSuccessAck". It also does not provide any information about how to handle replies where the Transaction ID doesn't match a Transaction ID from a previously sent request. If multiple controllers are connected to a single switch and the switch send an event message with "ReturnReceipt" set to all of them, there is no way for the switch to identify which controller the receipt is coming from. 7.2. Window Size The Switch Configuration Message defined in chapter 8.1 in [5] defines a Window size to be used by the controller when sending messages to the switch. It is not stated if this window should apply to all messages or only to messages that will always generate a reply. If messages that may not generate a reply should be counted against the window a time-out period when they are to be removed from the window should be defined. It is not defined if the window should be cleared when the adjacency is lost and later recovered. 7.2.2. Retransmission A retransmission policy should be used if no reply is received for a message with "AckAll" set. Kullgren, et. al. GSMP WG - June 2002 11 draft-ietf-gsmp-reqs-02.txt December 2002 7.3. Delete Branches Message The "Delete Branch Element" has a 4 bit Error field that should be redefined to match the size of the "Failure Response Codes". 7.4. Adjacency The chapter about how to handle a new adjacency and re-established adjacencies should be clarified. 7.4.1. Loss of Synchronization If a controller looses synchronization, the draft requires the switch to reset the connection state. This should be redefined since more than one controller may be synchronized to a switch partition. This change will affect the definition of the PFlag. 7.5. ReturnReceipt Result value in Events When the GSMP V3 initially was defined the events was supposed to be generated in a similar fashion as SNMP Traps. When an event was sent it was a uni-direction message and there was no requirement of the switch to verify that a controller received the message. Since event messages never expected a reply of a sent message there where no need of a Transaction Identifier. In the case of Event Messages the Transaction Identifier was decided it SHOULD be set to zero. Later on, a new Result Value of ReturnReceipt was introduced. ReturnReceipt is a results field used in Events to indicate that a switch requires an acknowledgment for the message. Introduced at the same time was the allowance of Multiple Controllers jointly controlling the same partition. Since all Transaction Identifiers is set to zero in the case of Event Messages the following problem can occur. 1. A switch has multiple controllers jointly controlling a partition. 2. The switch is configured to require acknowledgment of sent events. 3. For some reason one or more controller can not send the acknowledgment. 4. The switch has no ability to find out which controller that did not respond. Kullgren, et. al. GSMP WG - June 2002 12 draft-ietf-gsmp-reqs-02.txt December 2002 8. Security Considerations The security of GSMP's TCP/IP control channel has been addressed in [11]. Any potential remaining security considerations are not addressed in the current revision of this draft. 9. Acknowledgements The list of authors provided with this document is a reduction of the original list. Currently listed authors wish to acknowledge that a substantial amount was also contributed to this work by: Avri Doria and Kenneth Sundell The authors would like to acknowledge the careful review and comments of Dimitri Papadimitriou and Torbjorn Hedqvist. 10. References 1 Ashwood-Smith, D., et. al., "Generalized MPLS - Signaling Functional Description," Internet Draft draft-ietf-mpls- generalized-signaling-08.txt (work in progress), April 2002. 2 Mannie, E., et. al., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture," draft-ietf-ccamp-gmpls-architecture-02.txt (work in progress), March 2002. 3 International Telecommunications Union, "Architecture for the Automatic Switched Optical Network," G.8080, October 2001. 4 Doria, A, Sundell, K, Hellstrand, F, Worster, T, "General Switch Management Protocol V3," RFC 3292, June 2002. 5 Sadler, J., Mack-Crane, B., "TDM Labels for GSMP," draft-sadler- gsmp-tdm-labels-00.txt (work in progress), February 2001. 6 Rajagopalan, B., et. al., _IP over Optical Networks: A Framework, draft-ietf-ipo-framework-02.txt (work in progress), June 2002. 7 International Telecommunications Union, "Generic functional architecture of transport networks", G.805, March 2000. 8 Braden, R., "Integrated Services in the Internet Architecture: An Overview," RFC1633, June 1994. 9 J. Wroclawski, "Specification of the Controlled-Load Network Element Service," RFC2211, Sep 1997. 10 Blake, S., et. al., _"An Architecture for Differentiated Services," RFC2475, December 1998. Kullgren, et. al. GSMP WG - June 2002 13 draft-ietf-gsmp-reqs-02.txt December 2002 11 Worster, T, et. al., "GSMP Packet Encapsulations for ATM, Ethernet and TCP," RFC 3293, June 2002. 11. Author's Addresses Hormuzd Khosravi Intel 2111 NE 25th Avenue Hillsboro, OR 97124 USA Phone: +1 503 264 0334 Email: hormuzd.m.khosravi@intel.com Georg Kullgren Nortel Networks AB S:t Eriksgatan 115 A P.O. Box 6701 SE-113 85 Stockholm Sweden Email: geku@nortelnetworks.com Jonathan Sadler Tellabs Operations, Inc. 1415 West Diehl Road Naperville, IL 60563 Phone: +1 630-798-6182 Email: Jonathan.Sadler@tellabs.com Stephen Shew Nortel Networks PO Box 3511 Station C Ottawa, ON K1Y 4H7 Email: sdshew@nortelnetworks.com Kohei Shiomoto Email: Shiomoto.Kohei@lab.ntt.co.jp Atsushi Watanabe Nippon Telegraph and Telephone Corporation 807A 1-1 Hikari-no-oka, Yokosuka-shi Kanagawa 239-0847, Japan Email: atsushi@exa.onlab.ntt.co.jp Satoru Okamoto Nippon Telegraph and Telephone Corporation 9-11 Midori-cho 3-chome, Musashino-shi Tokyo 180-8585, Japan Email: okamoto@exa.onlab.ntt.co.jp Kullgren, et. al. GSMP WG - June 2002 14 draft-ietf-gsmp-reqs-02.txt December 2002 Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into Kullgren, et. al. GSMP WG - June 2002 15
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draft-ietf-gsmp-reqs-02
Internet-Draft
