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- Network Working Group F. Baker
- Request For Comments: 1354 ACC
- July 1992
-
-
- IP Forwarding Table MIB
-
- 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 routes in the IP
- Internet.
-
- It is proposed that the ipRouteTable defined by MIB-II (RFC 1213) be
- deprecated and replaced with this table. This adds the ability to
- set or display multi-path routes, and varying routes by network
- management policy.
-
- Table of Contents
-
- 1. The Network Management Framework ............................ 1
- 2. Objects ..................................................... 2
- 2.1 Format of Definitions ...................................... 2
- 3. Overview .................................................... 3
- 3.1 Structure of MIB ........................................... 3
- 4. Definitions ................................................. 4
- 4.1 IP Forwarding Table ........................................ 4
- 5. Acknowledgements ............................................ 11
- 6. References .................................................. 11
- 7. Security Considerations........................................ 12
- 8. Author's Address............................................... 12
-
- 1. The Network Management Framework
-
- The Internet-standard Network Management Framework consists of three
- components. They are:
-
- RFC 1155 which defines the SMI, the mechanisms used for describing
- and naming objects for the purpose of management. RFC 1212 defines a
-
-
-
- Baker [Page 1]
-
- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- more concise description mechanism, which is wholly consistent with
- the SMI.
-
- RFC 1156 which defines MIB-I, the core set of managed objects for the
- Internet suite of protocols. RFC 1213 defines MIB-II, an evolution
- of MIB-I based on implementation experience and new operational
- requirements.
-
- RFC 1157 which defines the SNMP, the protocol used for network access
- to managed objects.
-
- The Framework permits new objects to be defined for the purpose of
- experimentation and evaluation.
-
- 2. Objects
-
- Managed objects are accessed via a virtual information store, termed
- the Management Information Base or MIB. Objects in the MIB are
- defined using the subset of Abstract Syntax Notation One (ASN.1) [7]
- defined in 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 SMI [3] 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.
-
- The SMI specifies the use of the basic encoding rules of ASN.1 [8],
- subject to the additional requirements imposed by the SNMP.
-
- 2.1. Format of Definitions
-
- Section 4 contains contains the specification of all object types
- contained in this MIB module. The object types are defined using the
- conventions defined in the SMI, as amended by the extensions
- specified in [9].
-
-
-
-
- Baker [Page 2]
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- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- 3. Overview
-
- 3.1. Structure of MIB
-
- The IP Forwarding Table is quite analogous to the older ipRoute
- Table. The principal differences are:
-
- (1) It is somewhat re-organized, for aesthetic reasons,
-
- (2) It has the Next Hop Autonomous System Number, useful
- primarily to the administrators of regional networks,
-
- (3) It is instanced by Policy and Next Hop as well as by
- ultimate destination. Thus, multiple multipath routes
- can be managed, not just a single route, along with the
- circumstances under which the any given route might be
- chosen.
-
- 4. Definitions
-
- RFC1354-MIB DEFINITIONS ::= BEGIN
-
- IMPORTS
- Gauge, IpAddress
- FROM RFC1155-SMI
- mib-2, ip
- FROM RFC1213-MIB
- OBJECT-TYPE
- FROM RFC-1212;
-
- -- This MIB module uses the extended OBJECT-TYPE macro as
- -- defined in [9].
- ipForward OBJECT IDENTIFIER ::= { ip 24 }
-
- ipForwardNumber OBJECT-TYPE
- SYNTAX Gauge
- ACCESS read-only
- STATUS mandatory
- DESCRIPTION
- "The number of current ipForwardTable entries
- that are not invalid."
- ::= { ipForward 1 }
-
-
- -- IP Forwarding Table
-
- -- The IP Forwarding Table obsoletes and replaces the ipRoute
- -- Table current in MIB-I and MIB-II. It adds knowledge of
-
-
-
- Baker [Page 3]
-
- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- -- the autonomous system of the next hop, multiple next hop
- -- support, and policy routing support.
-
-
- ipForwardTable OBJECT-TYPE
- SYNTAX SEQUENCE OF IpForwardEntry
- ACCESS not-accessible
- STATUS mandatory
- DESCRIPTION
- "This entity's IP Routing table."
- REFERENCE
- "RFC 1213 Section 6.6, The IP Group"
- ::= { ipForward 2 }
-
-
- ipForwardEntry OBJECT-TYPE
- SYNTAX IpForwardEntry
- ACCESS not-accessible
- STATUS mandatory
- DESCRIPTION
- "A particular route to a particular destina-
- tion, under a particular policy."
- INDEX {
- ipForwardDest,
- ipForwardProto,
- ipForwardPolicy,
- ipForwardNextHop
- }
- ::= { ipForwardTable 1 }
-
-
- IpForwardEntry ::=
- SEQUENCE {
- ipForwardDest
- IpAddress,
- ipForwardMask
- IpAddress,
- ipForwardPolicy
- INTEGER,
- ipForwardNextHop
- IpAddress,
- ipForwardIfIndex
- INTEGER,
- ipForwardType
- INTEGER,
- ipForwardProto
- INTEGER,
- ipForwardAge
-
-
-
- Baker [Page 4]
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- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- INTEGER,
- ipForwardInfo
- OBJECT IDENTIFIER,
- ipForwardNextHopAS
- INTEGER,
- ipForwardMetric1
- INTEGER,
- ipForwardMetric2
- INTEGER,
- ipForwardMetric3
- INTEGER,
- ipForwardMetric4
- INTEGER,
- ipForwardMetric5
- INTEGER
- }
-
- ipForwardDest OBJECT-TYPE
- SYNTAX IpAddress
- ACCESS read-only
- STATUS mandatory
- DESCRIPTION
- "The destination IP address of this route. An
- entry with a value of 0.0.0.0 is considered a
- default route.
-
- This object may not take a Multicast (Class D)
- address value.
-
- Any assignment (implicit or otherwise) of an
- instance of this object to a value x must be
- rejected if the bitwise logical-AND of x with
- the value of the corresponding instance of the
- ipForwardMask object is not equal to x."
- ::= { ipForwardEntry 1 }
-
-
- ipForwardMask OBJECT-TYPE
- SYNTAX IpAddress
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "Indicate the mask to be logical-ANDed with the
- destination address before being compared to
- the value in the ipForwardDest field. For
- those systems that do not support arbitrary
- subnet masks, an agent constructs the value of
- the ipForwardMask by reference to the IP Ad-
-
-
-
- Baker [Page 5]
-
- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- dress Class.
-
- Any assignment (implicit or otherwise) of an
- instance of this object to a value x must be
- rejected if the bitwise logical-AND of x with
- the value of the corresponding instance of the
- ipForwardDest object is not equal to ipForward-
- Dest."
- DEFVAL { '00000000'h } -- 0.0.0.0
- ::= { ipForwardEntry 2 }
-
-
- -- The following convention is included for specification
- -- of TOS Field contents. At this time, the Host Requirements
- -- and the Router Requirements documents disagree on the width
- -- of the TOS field. This mapping describes the Router
- -- Requirements mapping, and leaves room to widen the TOS field
- -- without impact to fielded systems.
-
- ipForwardPolicy OBJECT-TYPE
- SYNTAX INTEGER
- ACCESS read-only
- STATUS mandatory
- DESCRIPTION
- "The general set of conditions that would cause
- the selection of one multipath route (set of
- next hops for a given destination) is referred
- to as 'policy'.
-
- Unless the mechanism indicated by ipForwardPro-
- to specifies otherwise, the policy specifier is
- the IP TOS Field. The encoding of IP TOS is as
- specified by the following convention. Zero
- indicates the default path if no more specific
- policy applies.
-
- +-----+-----+-----+-----+-----+-----+-----+-----+
- | | | |
- | PRECEDENCE | TYPE OF SERVICE | 0 |
- | | | |
- +-----+-----+-----+-----+-----+-----+-----+-----+
-
- IP TOS IP TOS
- Field Policy Field Policy
- Contents Code Contents Code
- 0 0 0 0 ==> 0 0 0 0 1 ==> 2
- 0 0 1 0 ==> 4 0 0 1 1 ==> 6
- 0 1 0 0 ==> 8 0 1 0 1 ==> 10
-
-
-
- Baker [Page 6]
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- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- 0 1 1 0 ==> 12 0 1 1 1 ==> 14
- 1 0 0 0 ==> 16 1 0 0 1 ==> 18
- 1 0 1 0 ==> 20 1 0 1 1 ==> 22
- 1 1 0 0 ==> 24 1 1 0 1 ==> 26
- 1 1 1 0 ==> 28 1 1 1 1 ==> 30
-
- Protocols defining 'policy' otherwise must ei-
- ther define a set of values which are valid for
- this object or must implement an integer-
- instanced policy table for which this object's
- value acts as an index."
- ::= { ipForwardEntry 3 }
-
-
- ipForwardNextHop OBJECT-TYPE
- SYNTAX IpAddress
- ACCESS read-only
- STATUS mandatory
- DESCRIPTION
- "On remote routes, the address of the next sys-
- tem en route; Otherwise, 0.0.0.0."
- ::= { ipForwardEntry 4 }
-
-
- ipForwardIfIndex OBJECT-TYPE
- SYNTAX INTEGER
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "The ifIndex value which identifies the local
- interface through which the next hop of this
- route should be reached."
- DEFVAL { 0 }
- ::= { ipForwardEntry 5 }
-
-
- ipForwardType OBJECT-TYPE
- SYNTAX INTEGER {
- other (1), -- not specified by this MIB
- invalid (2), -- logically deleted
- local (3), -- local interface
- remote (4) -- remote destination
- }
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "The type of route. Note that local(3) refers
- to a route for which the next hop is the final
-
-
-
- Baker [Page 7]
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- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- destination; remote(4) refers to a route for
- which the next hop is not the final destina-
- tion.
-
- Setting this object to the value invalid(2) has
- the effect of invalidating the corresponding
- entry in the ipForwardTable object. That is,
- it effectively disassociates the destination
- identified with said entry from the route iden-
- tified 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 current-
- ly in use. Proper interpretation of such en-
- tries requires examination of the relevant ip-
- ForwardType object."
- DEFVAL { invalid }
- ::= { ipForwardEntry 6 }
-
- ipForwardProto OBJECT-TYPE
- SYNTAX INTEGER {
- other (1), -- not specified
- local (2), -- local interface
- netmgmt (3), -- static route
- icmp (4), -- result of ICMP Redirect
-
- -- the following are all dynamic
- -- routing protocols
- egp (5), -- Exterior Gateway Protocol
- ggp (6), -- Gateway-Gateway Protocol
- hello (7), -- FuzzBall HelloSpeak
- rip (8), -- Berkeley RIP or RIP-II
- is-is (9), -- Dual IS-IS
- es-is (10), -- ISO 9542
- ciscoIgrp (11), -- Cisco IGRP
- bbnSpfIgp (12), -- BBN SPF IGP
- ospf (13), -- Open Shortest Path First
- bgp (14), -- Border Gateway Protocol
- idpr (15) -- InterDomain Policy Routing
- }
- ACCESS read-only
- STATUS mandatory
- DESCRIPTION
- "The routing mechanism via which this route was
- learned. Inclusion of values for gateway rout-
- ing protocols is not intended to imply that
-
-
-
- Baker [Page 8]
-
- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- hosts should support those protocols."
- ::= { ipForwardEntry 7 }
-
-
- ipForwardAge OBJECT-TYPE
- SYNTAX INTEGER
- ACCESS read-only
- STATUS mandatory
- DESCRIPTION
- "The number of seconds since this route was
- last updated or otherwise determined to be
- correct. Note that no semantics of `too old'
- can be implied except through knowledge of the
- routing protocol by which the route was
- learned."
- DEFVAL { 0 }
- ::= { ipForwardEntry 8 }
-
-
- ipForwardInfo OBJECT-TYPE
- SYNTAX OBJECT IDENTIFIER
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "A reference to MIB definitions specific to the
- particular routing protocol which is responsi-
- ble for this route, as determined by the value
- specified in the route's ipForwardProto value.
- If this information is not present, its value
- should be set to the OBJECT IDENTIFIER { 0 0 },
- which is a syntactically valid object identif-
- ier, and any implementation conforming to ASN.1
- and the Basic Encoding Rules must be able to
- generate and recognize this value."
- DEFVAL { { 0 0 } } -- 0.0
- ::= { ipForwardEntry 9 }
-
-
- ipForwardNextHopAS OBJECT-TYPE
- SYNTAX INTEGER
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "The Autonomous System Number of the Next Hop.
- When this is unknown or not relevant to the
- protocol indicated by ipForwardProto, zero."
- DEFVAL { 0 }
- ::= { ipForwardEntry 10 }
-
-
-
- Baker [Page 9]
-
- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- ipForwardMetric1 OBJECT-TYPE
- SYNTAX INTEGER
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "The primary routing metric for this route.
- The semantics of this metric are determined by
- the routing-protocol specified in the route's
- ipForwardProto value. If this metric is not
- used, its value should be set to -1."
- DEFVAL { -1 }
- ::= { ipForwardEntry 11 }
-
-
- ipForwardMetric2 OBJECT-TYPE
- SYNTAX INTEGER
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "An alternate routing metric for this route.
- The semantics of this metric are determined by
- the routing-protocol specified in the route's
- ipForwardProto value. If this metric is not
- used, its value should be set to -1."
- DEFVAL { -1 }
- ::= { ipForwardEntry 12 }
-
-
- ipForwardMetric3 OBJECT-TYPE
- SYNTAX INTEGER
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "An alternate routing metric for this route.
- The semantics of this metric are determined by
- the routing-protocol specified in the route's
- ipForwardProto value. If this metric is not
- used, its value should be set to -1."
- DEFVAL { -1 }
- ::= { ipForwardEntry 13 }
-
-
- ipForwardMetric4 OBJECT-TYPE
- SYNTAX INTEGER
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "An alternate routing metric for this route.
-
-
-
- Baker [Page 10]
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- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- The semantics of this metric are determined by
- the routing-protocol specified in the route's
- ipForwardProto value. If this metric is not
- used, its value should be set to -1."
- DEFVAL { -1 }
- ::= { ipForwardEntry 14 }
-
-
- ipForwardMetric5 OBJECT-TYPE
- SYNTAX INTEGER
- ACCESS read-write
- STATUS mandatory
- DESCRIPTION
- "An alternate routing metric for this route.
- The semantics of this metric are determined by
- the routing-protocol specified in the route's
- ipForwardProto value. If this metric is not
- used, its value should be set to -1."
- DEFVAL { -1 }
- ::= { ipForwardEntry 15 }
-
- END
-
- 5. Acknowledgements
-
- This document was produced by the Router Requirements Working Group,
- of which Phil Almquist is the chair.
-
- Chris Gunner (DEC) and Keith McCloghrie (Hughes LAN Systems) made
- significant comments on it, and it is better for their input.
-
- 6. References
-
- [1] Cerf, V., "IAB Recommendations for the Development of Internet
- Network Management Standards", RFC 1052, NRI, April 1988.
-
- [2] Cerf, V., "Report of the Second Ad Hoc Network Management Review
- Group", RFC 1109, NRI, August 1989.
-
- [3] Rose M., and K. McCloghrie, "Structure and Identification of
- Management Information for TCP/IP-based internets", RFC 1155,
- Performance Systems International, Hughes LAN Systems, May 1990.
-
- [4] McCloghrie K., and M. Rose, "Management Information Base for
- Network Management of TCP/IP-based internets", RFC 1156, Hughes
- LAN Systems, Performance Systems International, May 1990.
-
-
-
-
-
- Baker [Page 11]
-
- RFC 1354 IP Forwarding Table MIB July 1992
-
-
- [5] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple
- Network Management Protocol", RFC 1157, SNMP Research,
- Performance Systems International, Performance Systems
- International, MIT Laboratory for Computer Science, May 1990.
-
- [6] McCloghrie K., and M. Rose, Editors, "Management Information
- Base for Network Management of TCP/IP-based internets", RFC
- 1213, Performance Systems International, March 1991.
-
- [7] Information processing systems - Open Systems Interconnection -
- Specification of Abstract Syntax Notation One (ASN.1),
- International Organization for Standardization, International
- Standard 8824, December 1987.
-
- [8] Information processing systems - Open Systems Interconnection -
- Specification of Basic Encoding Rules for Abstract Notation One
- (ASN.1), International Organization for Standardization,
- International Standard 8825, December 1987.
-
- [9] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions",
- RFC 1212, Performance Systems International, Hughes LAN Systems,
- March 1991.
-
- [10] McCloghrie K., and M. Rose, Editors, "Management Information
- Base for Network Management of TCP/IP-based internets", RFC
- 1213, Performance Systems International, March 1991.
-
- [11] Baker, F., and R. Coltun, "OSPF Version 2 Management Information
- Base", RFC 1253, ACC, Computer Science Center, August 1991.
-
- 7. Security Considerations
-
- Security issues are not discussed in this memo.
-
- 8. Author's Address
-
- Fred Baker
- Advanced Computer Communications
- 315 Bollay Drive
- Santa Barbara, CA 93117-6014
-
- Phone: (805) 685-4455
-
- EMail: fbaker@acc.com
-
-
-
-
-
-
-
- Baker [Page 12]
-