Internet Draft INTERNET DRAFT Avri Doria GSMP Working Group Kenneth Sundell Informational Track Nortel Networks July 2000 General Switch Management Protocol Applicability <draft-ietf-gsmp-applicability-01.txt> This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This memo provides an overview of the GSMP protocol and includes information relating to its deployment in a MPLS environment. Doria, Sundell Expires January 2001 [Page 1] Internet Draft GSMP Applicability July 2000 1. Overview The General Switch Management Protocol (GSMP) has been available to the IETF community for several years now as informational RFC's. Both GSMPv1.1 released in March 1996 as RFC1987 [2], and GSMPv2.0 released in August 1998 as RFC2297 [3] are available. Several vendors have implemented GSMPv1.1. In V1.1 and V2 GSMP was intended only for use with ATM switches. During the course of the last year, the GSMP working group has decided to expand the purview of GSMP to the point where it can be used to control a number of different kinds of switch and can thus live up to what its name indicates; a general switch management protocol. To do this, commands and arguments needed to be generalised, with sections added discussing the manner in which the generalised protocol could be applied to specific kinds of switches and port types. In short the protocol has gone through major changes in the last 24 months. GSMP provides an interface that can be used to separate the data forwarder from the routing and other control plane protocols such as LDP. As such it allows service providers to move away from monolithic systems that bundle control plane and data plane into a single tightly coupled system - usually in a single chassis. Separating the control components from the forwarding components and using GSMP for switch management, enables service providers to create multi-service systems composed of various vendors equipment. It also allows for a more dynamic means of adding services to their networks. The IETF GSMP working group was established in the routing area because GSMP was being seen as an optional part of the MPLS solution. In a MPLS system, it is possible to run the routing protocols and label distribution protocols on one system while passing data across a generic switch, e.g. an ATM switch. GSMP provides the switch resource management mechanism needed in such a scenario. GSMP has also been selected by the Multiservice Switching Forum(MSF) as its protocol of choice for the Switch Control Interface identified in their architecture. The MSF is an industry forum, which among its activities establishes their member's requirements and then works with the appropriate standards bodies to foster their goals. In the case of GSMP, the MSF presented the IETF GSMP Working Group with a set of requirements for GSMP. The working group has made a determined effort to comply with those requirements in its specifications. Doria, Sundell Expires January 2001 [Page 2] Internet Draft GSMP Applicability July 2000 2. GSMP V3 Document Set The current version of GSMP is documented in 3 documents: - GSMP: General Switch Management protocol V3 [5] - GSMP-ENCAPS: GSMP Packet Encapsulations for ATM, Ethernet and TCP[4] - GSMP-MIB: Definitions of Managed Objects for the General Switch Management Protocol [1] 3. General Description The General Switch Management Protocol V3 (GSMPv3) [5], is a general purpose protocol to control a label switch. GSMP allows a controller to establish and release connections across the switch; add and delete leaves on a multicast connection; reserve resources; manage switch ports; request configuration information; and request statistics. It also allows the switch to inform the controller of asynchronous events such as a link going down. The GSMP protocol is asymmetric, the controller being the master and the switch being the slave. A physical switch can be partitioned in many virtual switches. GSMP does not provide support for defining switch partitions. GSMP treats a virtual switch as if it were a physical switch. GSMP may be transported in three ways: - GSMP operation across an IP network is specified. - GSMP operation across an ATM virtual channel is specified. - GSMP operation across an Ethernet link is specified. Other encapsulations are possible, but have not been defined. Encapsulations are defined in [4]. A label switch is a frame or cell switch that supports connection oriented switching using the exact match forwarding algorithm based on labels attached to incoming cells or frames. A label switch may support multiple label types, however, each switch port can support only one label type. The label type supported by a given port is indicated in a port configuration message. Connections may be established between ports Doria, Sundell Expires January 2001 [Page 3] Internet Draft GSMP Applicability July 2000 supporting different label types using the adaptation methods. There are two forms of labels support; short 28 bit labels which are sufficient for many purposes and TLV labels which are defined for labels that do not fit in 28 bits. Examples of the label types that can use the short form include ATM, Frame Relay, and MPLS Generic Labels. Examples of labels which are defined to use the TLV form include DS1, DS3, E1, E3 and MPLS FECs. A connection across a switch is formed by connecting an incoming labelled channel to one or more outgoing labelled channels. Connections are generally referenced by the input port on which they arrive and the label values of their incoming labelled channel. In some messages connections are referenced by the output port. GSMP supports point-to-point and point-to-multipoint connections. A multipoint-to-point connection is specified by establishing multiple point-to-point connections each of which specifies the same output label. A multipoint-to-multipoint connection is specified by establishing multiple point-to-multipoint connections each of which specifies a different input label with the same output labels. In general a connection is established with a certain quality of service (QoS). This version of GSMP includes a default QoS Configuration and additionally allows the negotiation of alternative, optional QoS configurations. The default QoS Configuration includes three QoS Models: a default service model, a simple priority model and a QoS profile model. This version of GSMP also supports the reservation of resources when the labels are not yet known. This ability can be used in support of MPLS. GSMP contains an adjacency protocol. The adjacency protocol is used to synchronise state across the link, to negotiate which version of the GSMP protocol to use, to discover the identity of the entity at the other end of a link, and to detect when it changes. 3.1 Switch Partitioning In this version of GSMP switch partitioning is static and occurs prior to running GSMP. The partitions of a physical switch are isolated from each other by the implementation and the controller assumes that the resources allocated to a partition are at all times available to that partition and only to that partition. A partition appears to its controller as a physical label switch. The resources allocated to a partition appear to the controller as Doria, Sundell Expires January 2001 [Page 4] Internet Draft GSMP Applicability July 2000 if they were the actual physical resources of a physical switch. For example if the bandwidth of a port is divided among several partitions, each partition would appear to the controller to have its own independent port with its fixed set or resources. GSMP controls a partitioned switch through the use of a partition identifier that is carried in every GSMP message. Each partition has a one-to-one control relationship with its own logical controller entity (which in the remainder of the document is referred to simply as a controller) and GSMP independently maintains adjacency between each controller-partition pair. 3.2 Switch and controller interactions Multiple switches may be controlled by a single controller using multiple instantiations of the protocol over separate control connections. Alternatively, multiple controllers can control a single switch. Each controller would establish a control connection to the switch using the adjacency protocol. The adjacency mechanism maintains a state table indicating the control connections that are being maintained by the same partition. The switch provides information to the controller group about the number and identity of the attached controllers. It does nothing, however, to co-ordinate the activities of the controllers, and will execute all commands as they are received. It is the controller group responsibility to co-ordinate its use of the switch. This mechanism is most commonly used for controller redundancy and load sharing. Definition of the mechanism by which controllers use to co- ordinate their control is not within GSMP's scope. 3.3 Service support All GSMP switches must support the default QoS Configuration. A GSMP switch may additionally support one or more alternative QoS Configurations. GSMP includes a negotiation mechanism that allows a controller to select from the QoS configurations that a switch supports. The default QoS Configuration includes three models: The Service Model is based on service definitions found external to GSMP such as in CR-LDP, Integrated Services or ATM Service Categories. Each connection is assigned a specific service that defines the handling of the connection by the switch. Additionally, traffic parameters Doria, Sundell Expires January 2001 [Page 5] Internet Draft GSMP Applicability July 2000 and traffic controls may be assigned to the connection depending on the assigned service. In the Simple Abstract Model a connection is assigned a priority when it is established. It may be assumed that for connections that share the same output port, an cell or frame on a connection with a higher priority is much more likely to exit the switch before a cell or frame on a connection with a lower priority if they are both in the switch at the same time. The QoS Profile Model provides a simple mechanism that allows QoS semantics defined externally to GSMP to be assigned to connections. Each profile is an opaque indicator that has been predefined in the controller and in the switch. Doria, Sundell Expires January 2001 [Page 6] Internet Draft GSMP Applicability July 2000 4. Summary of Message Set The following table gives a summary of the messages defined in this version of the specification. It also makes a recommendation of the minimal set of messages that should be supported in an MPLS environment. These messages will be labelled as "Required", though the service provided by the other messages are essential for the operation of carrier quality controller/ switch operations. GSMPv1.1 or GSMPv2 commands that are no longer support are marked as "Obsolete" and should no longer be used. 4.1 Messages Table Message Name Message Number Status Connection Management Messages Add Branch .......................16 Required ATM Specific - VPC............26 Delete Tree.......................18 Verify Tree.......................19 Obsoleted Delete All Input..................20 Delete All Output.................21 Delete Branches...................17 Required Move Output Branch............... 22 ATM Specific - VPC............27 Move Input Branch.................23 ATM Specific - VPC............28 Port Management Messages Port Management...................32 Required Label Range.......................33 State and Statistics Messages Connection Activity...............48 Port Statistics...................49 Required Connection Statistics.............50 QoS Class Statistics..............51 Reserved Report Connection State...........52 Configuration Messages Switch Configuration..............64 Required Port Configuration................65 Required All Ports Configuration...........66 Required Service Configuration.............67 Doria, Sundell Expires January 2001 [Page 7] Internet Draft GSMP Applicability July 2000 Reservation Messages Reservation Request.............. 70 Required Delete Reservation................71 Required Delete All Reservations...........72 Event Messages Port Up...........................80 Port Down.........................81 Invalid Label.....................82 New Port..........................83 Dead Port.........................84 Abstract and Resource Model Extension Messages Reserved.Message Range.............200-249 Adjacency Protocol....................10 Required 5. Security Considerations The security of GSMP's TCP/IP control channel has been addressed in [4]. Any potential remaining security considerations are not addressed in the current revision of this draft. Doria, Sundell Expires January 2001 [Page 8] Internet Draft GSMP Applicability July 2000 References [1] [GSMP-MIB] Sjostrand, H., "Definitions of Managed Objects for the General Switch Management Protocol (GSMP),"Internet-Draft draft-ietf-gsmp-mib- 02", July 2000. work in progress [2] [GSMPv1.1] Newman, P, Edwards, W., Hinden, R., Hoffman, E. Ching Liaw, F., Lyon, T. and Minshall, G., "Ipsilon's General Switch Management Protocol Specification," Version 1.1, RFC 1987, August 1996. [3] [GSMPv2] Newman, P, Edwards, W., Hinden, R., Hoffman, E., Ching Liaw, F., Lyon, T. and Minshall, G., "Ipsilon's General Switch Management Protocol Specification," Version 2.0, RFC 2397, March 1998. [4] [GSMP-ENCAPS] T. Worster, "GSMP Packet Encapsulations for ATM, Ethernet and TCP," Internet-Draft draft- ietf-gsmp-encaps-02, July 2000. work in progress [5] [GSMP] Doria, A, Sundell, K, Hellstrand, F, Worster, T, "General switch Management Protocol V3," Internet Draft draft-ietf-gsmp-06.txt, July 2000. work in progress Authors' Addresses Avri Doria Nortel Networks 600 Technology Park Drive Billerica, MA Phone: +1 401 663 5024 avri@nortelnetworks.com Kenneth Sundell Nortel Networks AB S:t Eriksgatan 115 A P.O. Box 6701 SE-113 85 Stockholm Sweden ksundell@nortelnetworks.com Doria, Sundell Expires January 2001 [Page 9]