Network Working Group M. Rose, Editor Request for Comments: 1158 Performance Systems International May 1990 Management Information Base for Network Management of TCP/IP-based internets: MIB-II 1. Status of this Memo This memo defines the second version of the Management Information Base (MIB-II) for use with network management protocols in TCP/IP- based internets. In particular, together with its companion memos which describe the structure of management information (RFC 1155) along with the network management protocol (RFC 1157) for TCP/IP- based internets, these documents provide a simple, workable architecture and system for managing TCP/IP-based internets and in particular the Internet community. This document on MIB-II incorporates all of the technical content of RFC 1156 on MIB-I and extends it, without loss of compatibilty. However, MIB-I as described in RFC 1156 is full Standard Protocol of the Internet, while the MIB-II described here is Proposed Standard Protocol of the Internet. This memo defines a mandatory extension to the base MIB (RFC 1156) and is a Proposed Standard for the Internet community. The extensions described here are currently Elective, but when they become a standard, they will have the same status as RFC 1156, that is, Recommended. The Internet Activities Board recommends that all IP and TCP implementations be network manageable. This implies implementation of the Internet MIB (RFC 1156 and the extensions in RFC 1158) and at least one of the two recommended management protocols SNMP (RFC 1157) or CMOT (RFC 1095). This version of the MIB specification, MIB-II, is an incremental refinement of MIB-I. As such, it has been designed according to two criteria: first, changes have been made in response to new operational requirements in the Internet; and, second, the changes are entirely upwards compatible in order to minimize impact on the network as the managed nodes in the Internet transition from MIB-I to MIB-II. It is expected that additional MIB groups and variables will be defined over time to accommodate the monitoring and control needs of new or changing components of the Internet. IETF SNMP Working Group [Page 1] RFC 1158 MIB II May 1990 Please refer to the latest edition of the "IAB Official Protocol Standards" RFC for current information on the state and status of standard Internet protocols. Distribution of this memo is unlimited. Table of Contents 1. Status of this Memo .................................. 1 2. Introduction ......................................... 3 3. Changes from MIB-I ................................... 4 3.1 Deprecated Objects .................................. 4 3.2 Display Strings ..................................... 5 3.3 The System Group .................................... 5 3.4 The Interfaces Group ................................ 5 3.5 The Address Translation Group ....................... 6 3.6 The IP Group ........................................ 7 3.7 The ICMP Group ...................................... 7 3.8 The TCP Group ....................................... 7 3.9 The UDP Group ....................................... 7 3.10 The EGP Group ...................................... 8 3.11 The Transmission Group ............................. 8 3.12 The SNMP Group ..................................... 8 4. Objects .............................................. 8 4.1 Object Groups ....................................... 9 4.2 Format of Definitions ............................... 10 5. Object Definitions ................................... 10 5.1 The System Group .................................... 11 5.2 The Interfaces Group ................................ 14 5.2.1 The Interfaces table .............................. 15 5.3 The Address Translation Group ....................... 27 5.4 The IP Group ........................................ 30 5.4.1 The IP Address table .............................. 38 5.4.2 The IP Routing table .............................. 41 5.4.3 The IP Address Translation table .................. 48 5.5 The ICMP Group ...................................... 51 5.6 The TCP Group ....................................... 61 5.6.1 The TCP Connection table .......................... 66 5.6.2 Additional TCP Objects ............................ 69 5.7 The UDP Group ....................................... 70 5.7.1 The UDP Listener table ............................ 72 5.8 The EGP Group ....................................... 73 5.8.1 The EGP Neighbor table ............................ 75 5.8.2 Additional EGP variables .......................... 83 5.9 The Transmission Group .............................. 83 5.10 The SNMP Group ..................................... 83 6. Definitions .......................................... 95 IETF SNMP Working Group [Page 2] RFC 1158 MIB II May 1990 7. Identification of OBJECT instances for use with the SNMP ................................................. 126 7.1 ifTable Object Type Names ........................... 127 7.2 atTable Object Type Names ........................... 127 7.3 ipAddrTable Object Type Names ....................... 128 7.4 ipRoutingTable Object Type Names .................... 128 7.5 ipNetToMediaTable Object Type Names ................. 129 7.6 tcpConnTable Object Type Names ...................... 129 7.7 udpTable Object Type Names .......................... 130 7.8 egpNeighTable Object Type Names ..................... 130 8. Acknowledgements .................................... 130 9. References .......................................... 131 10. Security Considerations.............................. 133 11. Author's Address..................................... 133 2. Introduction As reported in RFC 1052, IAB Recommendations for the Development of Internet Network Management Standards [1], a two-prong strategy for network management of TCP/IP-based internets was undertaken. In the short-term, the Simple Network Management Protocol (SNMP) was to be used to manage nodes in the Internet community. In the long-term, the use of the OSI network management framework was to be examined. Two documents were produced to define the management information: RFC 1065, which defined the Structure of Management Information (SMI) [2], and RFC 1066, which defined the Management Information Base (MIB) [3]. Both of these documents were designed so as to be compatible with both the SNMP and the OSI network management framework. This strategy was quite successful in the short-term: Internet-based network management technology was fielded, by both the research and commercial communities, within a few months. As a result of this, portions of the Internet community became network manageable in a timely fashion. As reported in RFC 1109, Report of the Second Ad Hoc Network Management Review Group [4], the requirements of the SNMP and the OSI network management frameworks were more different than anticipated. As such, the requirement for compatibility between the SMI/MIB and both frameworks was suspended. This action permitted the operational network management framework, the SNMP, to respond to new operational needs in the Internet community by producing this document. As such, the current network management framework for TCP/IP- based internets consists of: Structure and Identification of IETF SNMP Working Group [Page 3] RFC 1158 MIB II May 1990 Management Information for TCP/IP-based internets, RFC 1155 [13], which describes how managed objects contained in the MIB are defined; Management Information Base for Network Management of TCP/IP-based internets (version 2), this memo, which describes the managed objects contained in the MIB; and, the Simple Network Management Protocol, RFC 1157 [14], which defines the protocol used to manage these objects. Consistent with the IAB directive to produce simple, workable systems in the short-term, the list ofc objects (e.g., for BSD UNIX) were excluded. 7) It was agreed to avoid heavily instrumenting critical sections of code. The general guideline was one counter per critical section per layer. 3. Changes from MIB-I Features of this MIB include: 1) incremental additions to reflect new operational requirements; 2) upwards compatibility with the SMI/MIB and the SNMP; 3) improved support for multi-protocol entities; and, 4) textual clean-up of the MIB to improve clarity and readability. The objects defined in MIB-II have the OBJECT IDENTIFIER prefix: mib-2 OBJECT IDENTIFIER ::= { mgmt 1 } 3.1. Deprecated Objects In order to better prepare implementors for future changes in the MIB, a new term "deprecated" may be used when describing an object. A deprecated object in the MIB is one which must be supported, but one which will most likely be removed from the next version of the MIB (e.g., MIB-III). MIB-II marks one object as being deprecated: atTable As a result of deprecating the atTable object, the entire Address Translation group is deprecated. IETF SNMP Working Group [Page 4] RFC 1158 MIB II May 1990 Note that no functionality is lost with the deprecation of these objects: new objects providing equivalent or superior functionality are defined in MIB-II. 3.2. Display Strings In the past, there have been misinterpretations of the MIB as to when a string of octets should contain printable characters, meant to be displayed to a human. As a textual convention in the MIB, the datatype DisplayString ::= OCTET STRING is introduced. A DisplayString is restricted to the NVT ASCII character set, as defined in pages 10-11 of [7]. The following objects are now defined in terms of DisplayString: sysDescr ifDescr It should be noted that this change has no effect on either the syntax nor semantics of these objects. The use of the DisplayString notation is merely an artifact of the explanatory method used in MIB-II and future MIBs. Further, it should be noted that any object defined in terms of OCTET STRING may contain arbitrary binary data, in which each octet may take any value from 0 to 255 (decimal). 3.3. The System Group Four new objects are added to this group: sysContact sysName sysLocation sysServices These provide contact, administrative, location, and service information regarding the managed node. 3.4. The Interfaces Group The definition of the ifNumber object was incorrect, as it required all interfaces to support IP. (For example, devices without IP, such as MAC-layer bridges, could not be managed if this definition was strictly followed.) The description of the ifNumber object is changed IETF SNMP Working Group [Page 5] RFC 1158 MIB II May 1990 accordingly. The ifTable object was mistaken marked as read-write, it has been (correctly) re-designated as read-only. In addition, several new values have been added to the ifType column in the ifTable object: ppp(23) softwareLoopback(24) eon(25) ethernet-3Mbit(26) nsip(27) slip(28) Finally, a new column has been added to the ifTable object: ifSpecific which provides information about information specific to the media being used to realize the interface. 3.5. The Address Translation Group In MIB-I, this group contained a table which permitted mappings from network addresses (e.g., IP addresses) to physical addresses (e.g., MAC addresses). Experience has shown that efficient implementations of this table make two assumptions: a single network protocol environment, and mappings occur only from network address to physical address. The need to support multi-protocol nodes (e.g., those with both the IP and CLNP active), and the need to support the inverse mapping (e.g., for ES-IS), have invalidated both of these assumptions. As such, the atTable object is declared deprecated. In order to meet both the multi-protocol and inverse mapping requirements, MIB-II and its successors will allocate up to two address translation tables inside each network protocol group. That is, the IP group will contain one address translation table, for going from IP addresses to physical addresses. Similarly, when a document defining MIB objects for the CLNP is produced (e.g., [8]), it will contain two tables, for mappings in both directions, as this is required for full functionality. It should be noted that the choice of two tables (one for each direction of mapping) provides for ease of implementation in many cases, and does not introduce undue burden on implementations which realize the address translation abstraction through a single internal table. IETF SNMP Working Group [Page 6] RFC 1158 MIB II May 1990 3.6. The IP Group The access attribute of the variable ipForwarding has been changed from read-only to read-write. In addition, there is a new column to the ipAddrTable object, ipAdEntReasmMaxSize which keeps track of the largest IP datagram that can be re- assembled on a particular interface. There is also a new column in the ipRoutingTable object, ipRouteMask which is used for IP routing subsystems that support arbitrary subnet masks. One new object is added to the IP group: ipNetToMediaTable which is the address translation table for the IP group (providing identical functionality to the now deprecated atTable in the address translation group). 3.7. The ICMP Group There are no changes to this group. 3.8. The TCP Group Two new variables are added: tcpInErrs tcpOutRsts which keep track of the number of incoming TCP segments in error and the number of resets generated by a TCP. 3.9. The UDP Group A new table: udpTable is added. IETF SNMP Working Group [Page 7] RFC 1158 MIB II May 1990 3.10. The EGP Group Experience has indicated a need for additional objects that are useful in EGP monitoring. In addition to making several additions to the egpNeighborTable object, a new variable is added: egpAs which gives the autonomous system associated with this EGP entity. 3.11. The Transmission Group MIB-I was lacking in that it did not distinguish between different types of transmission media. A new group, the Transmission group, is allocated for this purpose: transmission OBJECT IDENTIFIER ::= { mib-2 10 } When Internet-standard definitions for managing transmission media are defined, the transmission group is used to provide a prefix for the names of those objects. Typically, such definitions reside in the experimental portion of the MIB until they are "proven", then as a part of the Internet standardization process, the definitions are accordingly elevated and a new object identifier, under the transmission group is defined. By convention, the name assigned is: type OBJECT IDENTIFIER ::= { transmission number } where "type" is the symbolic value used for the media in the ifType column of the ifTable object, and "number" is the actual integer value corresponding to the symbol. 3.12. The SNMP Group The application-oriented working groups of the IETF have been tasked to be receptive towards defining MIB variables specific to their respective applications. For the SNMP, it is useful to have statistical information. A new group, the SNMP group, is allocated for this purpose: snmp OBJECT IDENTIFIER ::= { mib-2 11 } 4. Objects Managed objects are accessed via a virtual information store, termed IETF SNMP Working Group [Page 8] RFC 1158 MIB II May 1990 the Management Information Base or MIB. Objects in the MIB are defined using Abstract Syntax Notation One (ASN.1) [9]. The mechanisms used for describing these objects are specified the companion memo, the SMI. In particular, each object has a name, a syntax, and an encoding. The name is an object identifier, an administratively assigned name, which specifies an object type. The object type together with an object instance serves to uniquely identify a specific instantiation of the object. For human convenience, we often use a textual string, termed the OBJECT DESCRIPTOR, to also refer to the object type. The syntax of an object type defines the abstract data structure corresponding to that object type. The ASN.1 language is used for this purpose. However, the companion memo purposely restricts the ASN.1 constructs which may be used. These restrictions are explicitly made for simplicity. The encoding of an object type is simply how that object type is represented using the object type's syntax. Implicitly tied to the notion of an object type's syntax and encoding is how the object type is represented when being transmitted on the network. This memo specifies the use of the basic encoding rules (BER) of ASN.1 [10], subject to the additional requirements imposed by the SNMP [14]. 4.1. Object Groups Since this list of managed objects contains only the essential elements, there is no need to allow individual objects to be optional. Rather, the objects are arranged into the following groups: - System - Interfaces - Address Translation (deprecated) - IP - ICMP - TCP - UDP - EGP - Transmission - SNMP There are two reasons for defining these groups: to provide a means of assigning object identifiers; and, to provide a method for implementations of managed agents to know which objects they must implement. This method is as follows: if the semantics of a group is applicable to an implementation, then it must implement all objects IETF SNMP Working Group [Page 9] RFC 1158 MIB II May 1990 in that group. For example, an implementation must implement the EGP group if and only if it implements the EGP. 4.2. Format of Definitions The next section contains the specification of all object types contained in the MIB. Following the conventions of the companion memo, the object types are defined using the following fields: OBJECT: ------- A textual name, termed the OBJECT DESCRIPTOR, for the object type, along with its corresponding OBJECT IDENTIFIER. Syntax: The abstract syntax for the object type, presented using ASN.1. This must resolve to an instance of the ASN.1 type ObjectSyntax defined in the SMI. Definition: A textual description of the semantics of the object type. Implementations should ensure that their interpretation of the object type fulfills this definition since this MIB is intended for use in multi- vendor environments. As such it is vital that object types have consistent meaning across all machines. Access: A keyword, one of read-only, read-write, write-only, or not-accessible. Note that this designation specifies the minimum level of support required. As a local matter, implementations may support other access types (e.g., an implementation may elect to permitting writing a variable marked herein as read-only). Further, protocol-specific "views" (e.g., those implied by an SNMP community) may make further restrictions on access to a variable. Status: A keyword, one of mandatory, optional, obsolete, or deprecated. Use of deprecated implies mandatory status. 5. Object Definitions RFC1158-MIB DEFINITIONS ::= BEGIN IETF SNMP Working Group [Page 10] RFC 1158 MIB II May 1990 IMPORTS mgmt, OBJECT-TYPE, NetworkAddress, IpAddress, Counter, Gauge, TimeTicks FROM RFC1155-SMI; DisplayString ::= OCTET STRING mib-2 OBJECT IDENTIFIER ::= { mgmt 1 } -- MIB-II system OBJECT IDENTIFIER ::= { mib-2 1 } interfaces OBJECT IDENTIFIER ::= { mib-2 2 } at OBJECT IDENTIFIER ::= { mib-2 3 } ip OBJECT IDENTIFIER ::= { mib-2 4 } icmp OBJECT IDENTIFIER ::= { mib-2 5 } tcp OBJECT IDENTIFIER ::= { mib-2 6 } udp OBJECT IDENTIFIER ::= { mib-2 7 } egp OBJECT IDENTIFIER ::= { mib-2 8 } -- cmot OBJECT IDENTIFIER ::= { mib-2 9 } transmission OBJECT IDENTIFIER ::= { mib-2 10 } snmp OBJECT IDENTIFIER ::= { mib-2 11 } END 5.1. The System Group Implementation of the System group is mandatory for all systems. OBJECT: ------- sysDescr { system 1 } Syntax: DisplayString (SIZE (0..255)) Definition: A textual description of the entity. This value should include the full name and version identification of the system's hardware type, software operating-system, and networking software. It is mandatory that this only contain printable ASCII characters. Access: read-only. Status: mandatory. IETF SNMP Working Group [Page 11] RFC 1158 MIB II May 1990 OBJECT: ------- sysObjectID { system 2 } Syntax: OBJECT IDENTIFIER Definition: The vendor's authoritative identification of the network management subsystem contained in the entity. This value is allocated within the SMI enterprises subtree (1.3.6.1.4.1) and provides an easy and unambiguous means for determining "what kind of box" is being managed. For example, if vendor "Flintstones, Inc." was assigned the subtree 1.3.6.1.4.1.4242, it could assign the identifier 1.3.6.1.4.1.4242.1.1 to its "Fred Router". Access: read-only. Status: mandatory. OBJECT: ------- sysUpTime { system 3 } Syntax: TimeTicks Definition: The time (in hundredths of a second) since the network management portion of the system was last re-initialized. Access: read-only. Status: mandatory. OBJECT: ------- sysContact { system 4 } Syntax: DisplayString (SIZE (0..255)) IETF SNMP Working Group [Page 12] RFC 1158 MIB II May 1990 Definition: The textual identification of the contact person for this managed node, together with information on how to contact this person. Access: read-write. Status: mandatory. OBJECT: ------- sysName { system 5 } Syntax: DisplayString (SIZE (0..255)) Definition: An administratively-assigned name for this managed node. By convention, this is the node's fully-qualified domain name. Access: read-write. Status: mandatory. OBJECT: ------- sysLocation { system 6 } Syntax: DisplayString (SIZE (0..255)) Definition: The physical location of this node (e.g., "telephone closet, 3rd floor"). Access: read-only. Status: mandatory. IETF SNMP Working Group [Page 13] RFC 1158 MIB II May 1990 OBJECT: ------- sysServices { system 7 } Syntax: INTEGER (0..127) Definition: A value which indicates the set of services that this entity potentially offers. The value is a sum. This sum initially takes the value zero, Then, for each layer, L, in the range 1 through 7, that this node performs transactions for, 2 raised to (L - 1) is added to the sum. For example, a node which performs only routing functions would have a value of 4 (2^(3-1)). In contrast, a node which is a host offering application services would have a value of 72 (2^(4-1) + 2^(7-1)). Note that in the context of the Internet suite of protocols, values should be calculated accordingly: layer functionality 1 physical (e.g., repeaters) 2 datalink/subnetwork (e.g., bridges) 3 internet (e.g., supports the IP) 4 end-to-end (e.g., supports the TCP) 7 applications (e.g., supports the SMTP) For systems including OSI protocols, layers 5 and 6 may also be counted. Access: read-only. Status: mandatory. 5.2. The Interfaces Group Implementation of the Interfaces group is mandatory for all systems. OBJECT: ------- ifNumber { interfaces 1 } Syntax: INTEGER IETF SNMP Working Group [Page 14] RFC 1158 MIB II May 1990 Definition: The number of network interfaces (regardless of their current state) present on this system. Access: read-only. Status: mandatory. 5.2.1. The Interfaces table The Interfaces table contains information on the entity's interfaces. Each interface is thought of as being attached to a "subnetwork". Note that this term should not be confused with "subnet" which refers to an addressing partitioning scheme used in the Internet suite of protocols. OBJECT: ------- ifTable { interfaces 2 } Syntax: SEQUENCE OF IfEntry Definition: A list of interface entries. The number of entries is given by the value of ifNumber. Access: read-only. Status: mandatory. OBJECT: ------- ifEntry { ifTable 1 } IETF SNMP Working Group [Page 15] RFC 1158 MIB II May 1990 Syntax: IfEntry ::= SEQUENCE { ifIndex INTEGER, ifDescr DisplayString, ifType INTEGER, ifMtu INTEGER, ifSpeed Gauge, ifPhysAddress OCTET STRING, ifAdminStatus INTEGER, ifOperStatus INTEGER, ifLastChange TimeTicks, ifInOctets Counter, ifInUcastPkts Counter, ifInNUcastPkts Counter, ifInDiscards Counter, ifInErrors Counter, ifInUnknownProtos Counter, ifOutOctets Counter, ifOutUcastPkts Counter, ifOutNUcastPkts Counter, ifOutDiscards Counter, ifOutErrors Counter, ifOutQLen Gauge, ifSpecific OBJECT IDENTIFIER } IETF SNMP Working Group [Page 16] RFC 1158 MIB II May 1990 Definition: An interface entry containing objects at the subnetwork layer and below for a particular interface. Access: read-only. Status: mandatory. We now consider the individual components of each interface entry: OBJECT: ------- ifIndex { ifEntry 1 } Syntax: INTEGER Definition: A unique value for each interface. Its value ranges between 1 and the value of ifNumber. The value for each interface must remain constant at least from one re- initialization of the entity's network management system to the next re-initialization. Access: read-only. Status: mandatory. OBJECT: ------- ifDescr { ifEntry 2 } Syntax: DisplayString (SIZE (0..255)) Definition: A textual string containing information about the interface. This string should include the name of the manufacturer, the product name and the version of the hardware interface. IETF SNMP Working Group [Page 17] RFC 1158 MIB II May 1990 Access: read-only. Status: mandatory. OBJECT: ------- ifType { ifEntry 3 } Syntax: INTEGER { other(1), -- none of the following regular1822(2), hdh1822(3), ddn-x25(4), rfc877-x25(5), ethernet-csmacd(6), iso88023-csmacd(7), iso88024-tokenBus(8), iso88025-tokenRing(9), iso88026-man(10), starLan(11), proteon-10Mbit(12), proteon-80Mbit(13), hyperchannel(14), fddi(15), lapb(16), sdlc(17), t1-carrier(18), cept(19), -- european equivalent of T-1 basicISDN(20), primaryISDN(21), -- proprietary serial propPointToPointSerial(22), ppp(23), softwareLoopback(24), eon(25), -- CLNP over IP [12] ethernet-3Mbit(26) nsip(27), -- XNS over IP slip(28) -- generic SLIP } Definition: The type of interface, distinguished according to the physical/link protocol(s) immediately "below" the network layer in the protocol stack. IETF SNMP Working Group [Page 18] RFC 1158 MIB II May 1990 Access: read-only. Status: mandatory. OBJECT: ------- ifMtu { ifEntry 4 } Syntax: INTEGER Definition: The size of the largest datagram which can be sent/received on the interface, specified in octets. For interfaces that are used for transmitting network datagrams, this is the size of the largest network datagram that can be sent on the interface. Access: read-only. Status: mandatory. OBJECT: ------- ifSpeed { ifEntry 5 } Syntax: Gauge Definition: An estimate of the interface's current bandwidth in bits per second. For interfaces which do not vary in bandwidth or for those where no accurate estimation can be made, this object should contain the nominal bandwidth. Access: read-only. Status: mandatory. IETF SNMP Working Group [Page 19] RFC 1158 MIB II May 1990 OBJECT: ------- ifPhysAddress { ifEntry 6 } Syntax: OCTET STRING Definition: The interface's address at the protocol layer immediately "below" the network layer in the protocol stack. For interfaces which do not have such an address (e.g., a serial line), this object should contain an octet string of zero length. Access: read-only. Status: mandatory. OBJECT: ------- ifAdminStatus { ifEntry 7 } Syntax: INTEGER { up(1), -- ready to pass packets down(2), testing(3) -- in some test mode } Definition: The desired state of the interface. The testing(3) state indicates that no operational packets can be passed. Access: read-write. Status: mandatory. OBJECT: ------- ifOperStatus { ifEntry 8 } IETF SNMP Working Group [Page 20] RFC 1158 MIB II May 1990 Syntax: INTEGER { up(1), -- ready to pass packets down(2), testing(3) -- in some test mode } Definition: The current operational state of the interface. The testing(3) state indicates that no operational packets can be passed. Access: read-only. Status: mandatory. OBJECT: ------- ifLastChange { ifEntry 9 } Syntax: TimeTicks Definition: The value of sysUpTime at the time the interface entered its current operational state. If the current state was entered prior to the last re-initialization of the local network management subsystem, then this object contains a zero value. Access: read-only. Status: mandatory. OBJECT: ------- ifInOctets { ifEntry 10 } Syntax: Counter IETF SNMP Working Group [Page 21] RFC 1158 MIB II May 1990 Definition: The total number of octets received on the interface, including framing characters. Access: read-only. Status: mandatory. OBJECT: ------- ifInUcastPkts { ifEntry 11 } Syntax: Counter Definition: The number of subnetwork-unicast packets delivered to a higher-layer protocol. Access: read-only. Status: mandatory. OBJECT: ------- ifInNUcastPkts { ifEntry 12 } Syntax: Counter Definition: The number of non-unicast (i.e., subnetwork-broadcast or subnetwork-multicast) packets delivered to a higher-layer protocol. Access: read-only. Status: mandatory. IETF SNMP Working Group [Page 22] RFC 1158 MIB II May 1990 OBJECT: ------- ifInDiscards { ifEntry 13 } Syntax: Counter Definition: The number of inbound packets which were chosen to be discarded even though no errors had been detected to prevent their being deliverable to a higher-layer protocol. One possible reason for discarding such a packet could be to free up buffer space. Access: read-only. Status: mandatory. OBJECT: ------- ifInErrors { ifEntry 14 } Syntax: Counter Definition: The number of inbound packets that contained errors preventing them from being deliverable to a higher-layer protocol. Access: read-only. Status: mandatory. OBJECT: ------- ifInUnknownProtos { ifEntry 15 } Syntax: Counter IETF SNMP Working Group [Page 23] RFC 1158 MIB II May 1990 Definition: The number of packets received via the interface which were discarded because of an unknown or unsupported protocol. Access: read-only. Status: mandatory. OBJECT: ------- ifOutOctets { ifEntry 16 } Syntax: Counter Definition: The total number of octets transmitted out of the interface, including framing characters. Access: read-only. Status: mandatory. OBJECT: ------- ifOutUcastPkts { ifEntry 17 } Syntax: Counter Definition: The total number of packets that higher-level protocols requested be transmitted to a subnetwork-unicast address, including those that were discarded or not sent. Access: read-only. Status: mandatory. IETF SNMP Working Group [Page 24] RFC 1158 MIB II May 1990 OBJECT: ------- ifOutNUcastPkts { ifEntry 18 } Syntax: Counter Definition: The total number of packets that higher-level protocols requested be transmitted to a non-unicast (i.e., a subnetwork-broadcast or subnetwork-multicast) address, including those that were discarded or not sent. Access: read-only. Status: mandatory. OBJECT: ------- ifOutDiscards { ifEntry 19 } Syntax: Counter Definition: The number of outbound packets which were chosen to be discarded even though no errors had been detected to prevent their being transmitted. One possible reason for discarding such a packet could be to free up buffer space. Access: read-only. Status: mandatory. OBJECT: ------- ifOutErrors { ifEntry 20 } Syntax: Counter IETF SNMP Working Group [Page 25] RFC 1158 MIB II May 1990 Definition: The number of outbound packets that could not be transmitted because of errors. Access: read-only. Status: mandatory. OBJECT: ------- ifOutQLen { ifEntry 21 } Syntax: Gauge Definition: The length of the output packet queue (in packets). Access: read-only. Status: mandatory. OBJECT: ------- ifSpecific { ifEntry 22 } Syntax: OBJECT IDENTIFIER Definition: A reference to MIB definitions specific to the particular media being used to realize the interface. For example, if the interface is realized by an ethernet, then the value of this object refers to a document defining objects specific to ethernet. If an agent is not configured to have a value for any of these variables, the object identifier nullSpecific OBJECT IDENTIFIER ::= { 0 0 } is returned. Note that "nullSpecific" is a syntatically valid object identifier, and any conformant IETF SNMP Working Group [Page 26] RFC 1158 MIB II May 1990 implementation of ASN.1 and BER must be able to generate and recognize this value. Access: read-only. Status: mandatory. 5.3. The Address Translation Group Implementation of the Address Translation group is mandatory for all systems. Note however that this group is deprecated by MIB-II. That is, it is being included solely for compatibility with MIB-I nodes, and will most likely be excluded from MIB-III nodes. From MIB-II and onwards, each network protocol group contains its own address translation tables. The Address Translation group contains one table which is the union across all interfaces of the translation tables for converting a NetworkAddress (e.g., an IP address) into a subnetwork-specific address. For lack of a better term, this document refers to such a subnetwork-specific address as a "physical" address. Examples of such translation tables are: for broadcast media where ARP is in use, the translation table is equivalent to the ARP cache; or, on an X.25 network where non-algorithmic translation to X.121 addresses is required, the translation table contains the NetworkAddress to X.121 address equivalences. OBJECT: ------- atTable { at 1 } Syntax: SEQUENCE OF AtEntry Definition: The Address Translation tables contain the NetworkAddress to "physical" address equivalences. Some interfaces do not use translation tables for determining address equivalences (e.g., DDN-X.25 has an algorithmic method); if all interfaces are of this type, then the Address Translation table is empty, i.e., has zero entries. Access: read-write. IETF SNMP Working Group [Page 27] RFC 1158 MIB II May 1990 Status: deprecated. OBJECT: ------- atEntry { atTable 1 } Syntax: AtEntry ::= SEQUENCE { atIfIndex INTEGER, atPhysAddress OCTET STRING, atNetAddress NetworkAddress } Definition: Each entry contains one NetworkAddress to "physical" address equivalence. Access: read-write. Status: deprecated. We now consider the individual components of each Address Translation table entry: OBJECT: ------- atIfIndex { atEntry 1 } Syntax: INTEGER Definition: The interface on which this entry's equivalence is effective. The interface identified by a particular value of this index is the same interface as identified by the same value of ifIndex. Access: read-write. IETF SNMP Working Group [Page 28] RFC 1158 MIB II May 1990 Status: deprecated. OBJECT: ------- atPhysAddress { atEntry 2 } Syntax: OCTET STRING Definition: The media-dependent "physical" address. Setting this object to a null string (one of zero length) has the effect of invaliding the corresponding entry in the atTable object. That is, it effectively disassociates the interface identified with said entry from the mapping identified with said entry. It is an implementation-specific matter as to whether the agent removes an invalidated entry from the table. Accordingly, management stations must be prepared to receive tabular information from agents that corresponds to entries not currently in use. Proper interpretation of such entries requires examination of the relevant atPhysAddress object. Access: read-write. Status: deprecated. OBJECT: ------- atNetAddress { atEntry 3 } Syntax: NetworkAddress Definition: The NetworkAddress (e.g., the IP address) corresponding to the media-dependent "physical" address. Access: read-write. IETF SNMP Working Group [Page 29] RFC 1158 MIB II May 1990 Status: deprecated. 5.4. The IP Group Implementation of the IP group is mandatory for all systems. OBJECT: ------- ipForwarding { ip 1 } Syntax: INTEGER { forwarding(1), -- i.e., acting as a gateway not-forwarding(2) -- i.e., NOT acting as a gateway } Definition: The indication of whether this entity is acting as an IP gateway in respect to the forwarding of datagrams received by, but not addressed to, this entity. IP gateways forward datagrams. IP hosts do not (except those source-routed via the host). Access: read-write. Status: mandatory. OBJECT: ------- ipDefaultTTL { ip 2 } Syntax: INTEGER Definition: The default value inserted into the Time-To-Live field of the IP header of datagrams originated at this entity, whenever a TTL value is not supplied by the transport layer protocol. Access: read-write. IETF SNMP Working Group [Page 30] RFC 1158 MIB II May 1990 Status: mandatory. OBJECT: ------- ipInReceives { ip 3 } Syntax: Counter Definition: The total number of input datagrams received from interfaces, including those received in error. Access: read-only. Status: mandatory. OBJECT: ------- ipInHdrErrors { ip 4 } Syntax: Counter Definition: The number of input datagrams discarded due to errors in their IP headers, including bad checksums, version number mismatch, other format errors, time-to-live exceeded, errors discovered in processing their IP options, etc. Access: read-only. Status: mandatory. OBJECT: ------- ipInAddrErrors { ip 5 } Syntax: Counter IETF SNMP Working Group [Page 31] RFC 1158 MIB II May 1990 Definition: The number of input datagrams discarded because the IP address in their IP header's destination field was not a valid address to be received at this entity. This count includes invalid addresses (e.g., 0.0.0.0) and addresses of unsupported Classes (e.g., Class E). For entities which are not IP Gateways and therefore do not forward datagrams, this counter includes datagrams discarded because the destination address was not a local address. Access: read-only. Status: mandatory. OBJECT: ------- ipForwDatagrams { ip 6 } Syntax: Counter Definition: The number of input datagrams for which this entity was not their final IP destination, as a result of which an attempt was made to find a route to forward them to that final destination. In entities which do not act as IP Gateways, this counter will include only those packets which were Source-Routed via this entity, and the Source-Route option processing was successful. Access: read-only. Status: mandatory. OBJECT: ------- ipInUnknownProtos { ip 7 } Syntax: Counter IETF SNMP Working Group [Page 32] RFC 1158 MIB II May 1990 Definition: The number of locally-addressed datagrams received successfully but discarded because of an unknown or unsupported protocol. Access: read-only. Status: mandatory. OBJECT: ------- ipInDiscards { ip 8 } Syntax: Counter Definition: The number of input IP datagrams for which no problems were encountered to prevent their continued processing, but which were discarded (e.g., for lack of buffer space). Note that this counter does not include any datagrams discarded while awaiting re-assembly. Access: read-only. Status: mandatory. OBJECT: ------- ipInDelivers { ip 9 } Syntax: Counter Definition: The total number of input datagrams successfully delivered to IP user-protocols (including ICMP). Access: read-only. IETF SNMP Working Group [Page 33] RFC 1158 MIB II May 1990 Status: mandatory. OBJECT: ------- ipOutRequests { ip 10 } Syntax: Counter Definition: The total number of IP datagrams which local IP user- protocols (including ICMP) supplied to IP in requests for transmission. Note that this counter does not include any datagrams counted in ipForwDatagrams. Access: read-only. Status: mandatory. OBJECT: ipOutDiscards { ip 11 } Syntax: Counter Definition: The number of output IP datagrams for which no problem was encountered to prevent their transmission to their destination, but which were discarded (e.g., for lack of buffer space). Note that this counter would include datagrams counted in ipForwDatagrams if any such packets met this (discretionary) discard criterion. Access: read-only. Status: mandatory. OBJECT: ------- ipOutNoRoutes { ip 12 } IETF SNMP Working Group [Page 34] RFC 1158 MIB II May 1990 Syntax: Counter Definition: The number of IP datagrams discarded because no route could be found to transmit them to their destination. Note that this counter includes any packets counted in ipForwDatagrams which meet this "no-route" criterion. Note that this includes any datagarms which a host cannot route because all of its default gateways are down. Access: read-only. Status: mandatory. OBJECT: ------- ipReasmTimeout { ip 13 } Syntax: INTEGER Definition: The maximum number of seconds which received fragments are held while they are awaiting reassembly at this entity. Access: read-only. Status: mandatory. OBJECT: ------- ipReasmReqds { ip 14 } Syntax: Counter Definition: The number of IP fragments received which needed to be reassembled at this entity. IETF SNMP Working Group [Page 35] RFC 1158 MIB II May 1990 Access: read-only. Status: mandatory. OBJECT: ------- ipReasmOKs { ip 15 } Syntax: Counter Definition: The number of IP datagrams successfully re-assembled. Access: read-only. Status: mandatory. OBJECT: ------- ipReasmFails { ip 16 } Syntax: Counter Definition: The number of failures detected by the IP re-assembly algorithm (for whatever reason: timed out, errors, etc). Note that this is not necessarily a count of discarded IP fragments since some algorithms (notably the algorithm in RFC 815) can lose track of the number of fragments by combining them as they are received. Access: read-only. Status: mandatory. IETF SNMP Working Group [Page 36] RFC 1158 MIB II May 1990 OBJECT: ------- ipFragOKs { ip 17 } Syntax: Counter Definition: The number of IP datagrams that have been successfully fragmented at this entity. Access: read-only. Status: mandatory. OBJECT: ------- ipFragFails { ip 18 } Syntax: Counter Definition: The number of IP datagrams that have been discarded because they needed to be fragmented at this entity but could not be, e.g., because their "Don't Fragment" flag was set. Access: read-only. Status: mandatory. OBJECT: ------- ipFragCreates { ip 19 } Syntax: Counter Definition: The number of IP datagram fragments that have been generated as a result of fragmentation at this entity. IETF SNMP Working Group [Page 37] RFC 1158 MIB II May 1990 Access: read-only. Status: mandatory. 5.4.1. The IP Address table The Ip Address table contains this entity's IP addressing information. OBJECT: ------- ipAddrTable { ip 20 } Syntax: SEQUENCE OF IpAddrEntry Definition: The table of addressing information relevant to this entity's IP addresses. Access: read-only. Status: mandatory. OBJECT: ------- ipAddrEntry { ipAddrTable 1 } Syntax: IpAddrEntry ::= SEQUENCE { ipAdEntAddr IpAddress, ipAdEntIfIndex INTEGER, ipAdEntNetMask IpAddress, ipAdEntBcastAddr INTEGER, ipAdEntReasmMaxSize INTEGER (0..65535) } IETF SNMP Working Group [Page 38] RFC 1158 MIB II May 1990 Definition: The addressing information for one of this entity's IP addresses. Access: read-only. Status: mandatory. OBJECT: ------- ipAdEntAddr { ipAddrEntry 1 } Syntax: IpAddress Definition: The IP address to which this entry's addressing information pertains. Access: read-only. Status: mandatory. OBJECT: ------- ipAdEntIfIndex { ipAddrEntry 2 } Syntax: INTEGER Definition: The index value which uniquely identifies the interface to which this entry is applicable. The interface identified by a particular value of this index is the same interface as identified by the same value of ifIndex. Access: read-only. Status: mandatory. IETF SNMP Working Group [Page 39] RFC 1158 MIB II May 1990 OBJECT: ------- ipAdEntNetMask { ipAddrEntry 3 } Syntax: IpAddress Definition: The subnet mask associated with the IP address of this entry. The value of the mask is an IP address with all the network bits set to 1 and all the hosts bits set to 0. Access: read-only. Status: mandatory. OBJECT: ------- ipAdEntBcastAddr { ipAddrEntry 4 } Syntax: INTEGER Definition: The value of the least-significant bit in the IP broadcast address used for sending datagrams on the (logical) interface associated with the IP address of this entry. For example, when the Internet standard all-ones broadcast address is used, the value will be 1. This value applies to both the subnet and network broadcasts addresses used by the entity on this (logical) interface. Access: read-only. Status: mandatory. OBJECT: ------- ipAdEntReasmMaxSize { ipAddrEntry 5 } IETF SNMP Working Group [Page 40] RFC 1158 MIB II May 1990 Syntax: INTEGER (0..65535) Definition: The size of the largest IP datagram which this entity can re-assemble from incoming IP fragmented datagrams received on this interface. Access: read-only. Status: mandatory. 5.4.2. The IP Routing table The IP Routing table contains an entry for each route presently known to this entity. OBJECT: ------- ipRoutingTable { ip 21 } Syntax: SEQUENCE OF IpRouteEntry Definition: This entity's IP Routing table. Access: read-write. Status: mandatory. OBJECT: ------- ipRouteEntry { ipRoutingTable 1 } Syntax: IpRouteEntry ::= SEQUENCE { ipRouteDest IpAddress, ipRouteIfIndex INTEGER,