Network Working Group D. Throop Request for Comments: 1381 Data General Corporation F. Baker Advanced Computer Communications November 1992 SNMP MIB Extension for X.25 LAPB Status of this Memo This RFC specifies an IAB standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "IAB Official Protocol Standards" for the standardization state and status of this protocol. Distribution of this memo is unlimited. Abstract This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in TCP/IP-based internets. In particular, it defines objects for managing the Link Layer of X.25, LAPB. The objects defined here, along with the objects in the "SNMP MIB Extension for the Packet Layer of X.25" [9] and the "Definitions of Managed Objects for RS-232-like Hardware Devices" [8], combine to allow management of an X.25 protocol stack. Table of Contents 1. The Network Management Framework ....................... 2 2. Objects ................................................ 2 2.1 Format of Definitions ................................. 3 3. Overview ............................................... 3 3.1 Informal overview ..................................... 3 3.2 Textual Conventions ................................... 4 3.3 Formal overview ....................................... 4 3.4 Tables ................................................ 5 3.5 Traps ................................................. 6 4. Object Definitions ..................................... 6 5. Appendix: Revision History ............................. 27 July 30, 1992 .......................................... 27 June 12, 1992 .......................................... 27 May 18, 1992 ........................................... 28 April 8, 1992 .......................................... 28 February 1992 .......................................... 28 October 1991 ........................................... 29 June 1991 .............................................. 30 April 1991 ............................................. 30 Throop & Baker [Page 1] RFC 1381 X.25 LAPB MIB November 1992 6. Acknowledgements ....................................... 30 7. References ............................................. 31 8. Security Considerations ................................ 33 9. Authors' Addresses ..................................... 33 1. The Network Management Framework The Internet-standard Network Management Framework consists of three components. These components give the rules for defining objects, the definitions of objects, and the protocol for manipulating objects. The network management framework structures objects in an abstract information tree. The branches of the tree name objects and the leaves of the tree contain the values manipulated to effect management. This tree is called the Management Information Base or MIB. The concepts of this tree are given in STD 16/RFC 1155 "The Structure of Management Information" or SMI [1]. The SMI defines the trunk of the tree and the types of objects used when defining the leaves. STD 16/RFC 1212, "Towards Concise MIB Definitions" [4], defines a more concise description mechanism that preserves all the principals of the SMI. The core MIB definitions for the Internet suite of protocols can be found in RFC 1156 [2] "Management Information Base for Network Management of TCP/IP-based internets". STD 17/RFC 1213 [5] defines MIB-II, an evolution of MIB-I with changes to incorporate implementation experience and new operational requirements. STD 15/RFC 1157 [3] defines the SNMP protocol itself. The protocol defines how to manipulate the objects in a remote MIB. The tree structure of the MIB allows new objects to be defined for the purpose of experimentation and evaluation. 2. Objects The definition of an object in the MIB requires an object name and type. Object names and types are defined using the subset of the Abstract Syntax Notation One (ASN.1) [6] defined in the SMI [1]. Objects are named using ASN.1 object identifiers, administratively assigned names, to specify object types. The object name, together with an optional object instance, uniquely identifies a specific instance of an object. For human convenience, we often use a textual string, termed the OBJECT DESCRIPTOR, to also refer to objects. Objects also have a syntax that defines the abstract data structure corresponding to that object type. The ASN.1 language [6] provides Throop & Baker [Page 2] RFC 1381 X.25 LAPB MIB November 1992 the primitives used for this purpose. The SMI [1] purposely restricts the ASN.1 constructs which may be used for simplicity and ease of implementation. The encoding of an object type simply describes how to represent an object using ASN.1 encoding rules [7], for purposes of dealing with the SNMP protocol. 2.1. Format of Definitions Section 4 contains the specification of all object types defined in this MIB module. The object definitions use the conventions given in the SMI [1] as amended by the concise MIB definitions [4]. 3. Overview 3.1. Informal overview This section describes how the objects defined below relate with other MIBs. This section is only informational to help understand how the pieces fit together. The objects defined below are to be used in conjunction with MIB-II and other MIBs such as the X.25 packet level MIB [9]. A system with a complete X.25 stack running over a synchronous line will have at least two interfaces in the ifTable defined in MIB-II. There will be an interface for LAPB and another interface for the packet layer of X.25. There will also be objects defined in the RS-232-like MIB for the physical sync line. Each software interface identifies the layer below it used to send and receive packets. The X.25 MIB object, x25InfoDataLinkId, specifies an instance of lapbAdmnIndex for the LAPB interface under that X.25. The LAPB object, lapbOperPortId, defined below, identifies an instance of the rs232PortIndex for the the Sync line used by LAPB. For X.25 running over LAPB over Ethernet, the lapbAdmnPortId would identify the instance of ifIndex for the Ethernet interface. Each X.25 subnetwork will have separate entries in the ifTable. Thus a system with two X.25 lines would have two ifTable entries for the two X.25 packet layers and two other entries for the two LAPB interfaces. Each X.25 Packet Layer MIB would identify the instance of the LAPB MIB below it. Each LAPB MIB would identify the Sync line below it. The system would also have two entries for rs232PortTable and rs232SyncPortTable for the two physical lines. Since the ifTable as defined in MIB-II is device independent, it doesn't have anything specific for any type of interface. The objects below define the LAPB specific information for an interface Throop & Baker [Page 3] RFC 1381 X.25 LAPB MIB November 1992 of type LAPB. Different LAPB interfaces can also be differentiated by matching the values of ifIndex with lapbAdmnIndex. 3.2. Textual Conventions Two new data types are introduced as a textual conventions in this MIB document. These textual conventions enhance the readability of the specification and can ease comparison with other specifications if appropriate. It should be noted that the introduction of these textual conventions has no effect on either the syntax nor the semantics of any managed objects. The use of these is merely an artifact of the explanatory method used. Objects defined in terms of one of these methods are always encoded by means of the rules that define the primitive type. Hence, no changes to the SMI or the SNMP are necessary to accommodate these textual conventions which are adopted merely for the convenience of readers and writers in pursuit of the elusive goal of clear, concise, and unambiguous MIB documents. This MIB introduces the data types of: PositiveInteger ifIndexType 3.3. Formal overview Instances of the objects defined below represent attributes of a LAPB interface. LAPB interfaces are identified by an ifType object in the Internet-standard MIB [5] of lapb(16). For these interfaces, the value of the ifSpecific variable in the MIB-II [5] has the OBJECT IDENTIFIER value: lapb OBJECT IDENTIFIER ::= { transmission 16 } The relationship between a LAPB interface and an interface in the context of the Internet-standard MIB [5] is one-to-one. As such, the value of an ifIndex object instance can be directly used to identify corresponding instances of the objects defined below. The objects defined below are defined in the context of ISO 7776 [10] and ISO 8885 [11]. Access to those documents maybe useful (but isn't essential) to understand the names and semantics of some objects. Where possible the object descriptions use the terminology of ISO 7776; for example, one commonly used term refers to the peer LAPB as the DCE/remote DTE. This terminology does not restrict the instrumented LAPB to function only as a DTE. This MIB maybe applied Throop & Baker [Page 4] RFC 1381 X.25 LAPB MIB November 1992 to a LAPB configured as either a DCE or a DTE. To the extent that some attributes defined in the Internet standard MIB [5] are applicable to LAPB, those objects have not been duplicated here. In some instances some clarification of how to apply those objects to LAPB has been given. Some objects defined below include a DEFVAL clause. This clause provides reasonable (but not mandatory) default values to use when creating these objects. This does not imply this MIB defines any mechanism for creating or deleting LAPB interfaces. The creation and deletion of the objects of this MIB depend on the implementation method for creating and deleting LAPB interfaces. The DEFVAL clause provides reasonable defaults to allow further extension of the MIB to define methods for creating and deleting LAPB interfaces without having to deprecate these objects for the lack of a DEFVAL clause. 3.4. Tables This extension adds four tables to the MIB. These tables are: lapbAdmnTable, lapbOperTable, lapbFlowTable, and lapbXidTable. The lapbAdmnTable provides objects for common parameters used by LAPB such as the T1 retransmission timer or the N2 retransmission counter. Changes to objects in this table need not affect a running interface but provides access to the values used to initialize an interface. These values are read-write. The lapbOperTable provides objects to determine the parameters actually in use by an interface. These objects are read only. The values currently in use maybe different from the lapbAdmnTable values if the lapbAdmnTable was changed after interface initialization or if XID negotiation selected different values. The lapbFlowTable provides objects that report how the LAPB interface performs. These are read-only objects used to monitor operation. The lapbXidTable is not required for systems that do not transmit XID frames. For systems that do transmit XID frames, this table provides the values for the fields of the XID frame that are not already present in the lapbAdmnTable. The objects in this table are read- write. Throop & Baker [Page 5] RFC 1381 X.25 LAPB MIB November 1992 3.5. Traps Since all LAPB interfaces have entries in the ifTable, significant changes in the state of the interface should send a linkUp or linkDown trap. Thus an interface that receives or sends a Frame Reject frame should send a linkDown trap. If the interface later comes back up, it should then send a linkUP trap. 4. Object Definitions RFC1381-MIB DEFINITIONS ::= BEGIN IMPORTS Counter FROM RFC1155-SMI transmission FROM RFC1213-MIB OBJECT-TYPE FROM RFC-1212; -- LAPB MIB lapb OBJECT IDENTIFIER ::= { transmission 16 } PositiveInteger ::= INTEGER (0..2147483647) IfIndexType ::= INTEGER (1..2147483647) -- IfIndexType specifies an index object for a table -- with entries that match entries in the MIB-II ifTable. -- The value of the index for the table will match the -- ifIndex entry for same interface in the ifTable. -- The values of this object range from 1 to ifNumber -- inclusive. -- ########################################################### -- LAPB Admn Table -- ########################################################### -- Support of the lapbAdmnTable is mandatory for all -- agents of systems that implement LAPB. lapbAdmnTable OBJECT-TYPE SYNTAX SEQUENCE OF LapbAdmnEntry ACCESS not-accessible STATUS mandatory Throop & Baker [Page 6] RFC 1381 X.25 LAPB MIB November 1992 DESCRIPTION "This table contains objects that can be changed to manage a LAPB interface. Changing one of these parameters may take effect in the operating LAPB immediately or may wait until the interface is restarted depending on the details of the implementation. Most of the objects in this read-write table have corresponding read-only objects in the lapbOperTable that return the current operating value. The operating values may be different from these configured values if changed by XID negotiation or if a configured parameter was changed after the interface was started." ::= { lapb 1 } lapbAdmnEntry OBJECT-TYPE SYNTAX LapbAdmnEntry ACCESS not-accessible STATUS mandatory DESCRIPTION "Configured parameter values for a specific LAPB." INDEX { lapbAdmnIndex } ::= { lapbAdmnTable 1 } LapbAdmnEntry ::= SEQUENCE { lapbAdmnIndex IfIndexType, lapbAdmnStationType INTEGER, lapbAdmnControlField INTEGER, lapbAdmnTransmitN1FrameSize PositiveInteger, lapbAdmnReceiveN1FrameSize