Network Working Group F. Baker
Request for Comments: 2096 Cisco Systems
Obsoletes: 1354 January 1997
Category: Standards Track
IP Forwarding Table MIB
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
This memo defines an update to RFC 1354, "IP Forwarding Table MIB", for Classless Inter-Domain Routing (CIDR). That document was developed by the Router Requirements Working Group as an update to RFC 1213's ipRouteTable, with the display of multiple routes as a primary objective. The significant difference between this MIB and RFC 1354 is the recognition (explicitly discussed but by consensus left to future work) that CIDR routes may have the same network number but different network masks. Note that this MIB obsoletes a number of objects from RFC 1354. The reader should pay careful attention to the STATUS field.
Baker Standards Track [Page 1]
RFC 2096 IP Forwarding Table MIB January 19972. The SNMP Network Management Framework
The SNMP Network Management Framework presently consists of three major components. They are:
o the SMI, described in RFC 1902[1], - the mechanisms used for describing and naming objects for the purpose of management.
o the MIB-II, STD 17, RFC 1213[2], - the core set of managed objects for the Internet suite of protocols.
o the protocol, RFC 1157[6] and/or RFC 1905[4], - the protocol for accessing managed information.
Textual conventions are defined in RFC 1903[3], and conformance statements are defined in RFC 1904[5].
The Framework permits new objects to be defined for the purpose of experimentation and evaluation.
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) defined in the SMI. In particular, each object object type is named by an OBJECT IDENTIFIER, an administratively assigned name. 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 descriptor, to refer to the object type.
The MIB consists of two tables and two global objects.
(1) The object ipForwardNumber indicates the number of current routes. This is primarily to avoid having to read the table in order to determine this number.
(2) The ipForwardTable updates the RFC 1213 ipRouteTable to display multipath IP Routes. This is in turn obsoleted by the ipCidrRouteTable.
(3) The ipCidrRouteTable updates the RFC 1213 ipRouteTable to display multipath IP Routes having the same network number but differing network masks.
Baker Standards Track [Page 2]
RFC 2096 IP Forwarding Table MIB January 19974. Definitions
IP-FORWARD-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, OBJECT-TYPE, IpAddress, Integer32, Gauge32
FROM SNMPv2-SMI
RowStatus
FROM SNMPv2-TC
ip
FROM RFC1213-MIB
MODULE-COMPLIANCE, OBJECT-GROUP
FROM SNMPv2-CONF;
ipForward MODULE-IDENTITY
LAST-UPDATED "9609190000Z" -- Thu Sep 26 16:34:47 PDT 1996 ORGANIZATION "IETF OSPF Working Group" CONTACT-INFO
" Fred Baker
Postal: Cisco Systems
519 Lado Drive Santa Barbara, California 93111
Phone: +1 805 681 0115 Email: fred@cisco.com "
DESCRIPTION
"The MIB module for the display of CIDR multipath IP Routes."
REVISION "9609190000Z" DESCRIPTION
"Revisions made by the OSPF WG."
::= { ip 24 }
ipCidrRouteNumber OBJECT-TYPE
SYNTAX Gauge32 MAX-ACCESS read-only STATUS current DESCRIPTION "The number of current ipCidrRouteTable entries that are not invalid."
::= { ipForward 3 }
-- IP CIDR Route Table
-- The IP CIDR Route Table obsoletes and replaces the ipRoute -- Table current in MIB-I and MIB-II and the IP Forwarding Table. -- It adds knowledge of the autonomous system of the next hop, -- multiple next hops, and policy routing, and Classless -- Inter-Domain Routing.
ipCidrRouteTable OBJECT-TYPE SYNTAX SEQUENCE OF IpCidrRouteEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION
"This entity's IP Routing table."
REFERENCE
"RFC 1213 Section 6.6, The IP Group"
::= { ipForward 4 }
ipCidrRouteEntry OBJECT-TYPE
SYNTAX IpCidrRouteEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A particular route to a particular destina- tion, under a particular policy."
INDEX {
ipCidrRouteDest, ipCidrRouteMask, ipCidrRouteTos, ipCidrRouteNextHop }
::= { ipCidrRouteTable 1 }
ipCidrRouteDest OBJECT-TYPE
SYNTAX IpAddress MAX-ACCESS read-only STATUS current DESCRIPTION "The destination IP address of this 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 ipCidrRouteMask object is not equal to x."
::= { ipCidrRouteEntry 1 }
ipCidrRouteMask OBJECT-TYPE
SYNTAX IpAddress MAX-ACCESS read-only STATUS current DESCRIPTION "Indicate the mask to be logical-ANDed with the destination address before being compared to the value in the ipCidrRouteDest field. For those systems that do not support arbitrary subnet masks, an agent constructs the value of the ipCidrRouteMask by reference to the IP Ad- 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 ipCidrRouteDest object is not equal to ipCidrRoute- Dest."
-- 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.
ipCidrRouteTos OBJECT-TYPE SYNTAX Integer32 MAX-ACCESS read-only STATUS current DESCRIPTION "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 |
| | | |
+-----+-----+-----+-----+-----+-----+-----+-----+
ipCidrRouteNextHop OBJECT-TYPE
SYNTAX IpAddress MAX-ACCESS read-only STATUS current DESCRIPTION "On remote routes, the address of the next sys- tem en route; Otherwise, 0.0.0.0."
ipCidrRouteIfIndex OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS current DESCRIPTION "The ifIndex value which identifies the local interface through which the next hop of this route should be reached." DEFVAL { 0 } ::= { ipCidrRouteEntry 5 }
ipCidrRouteType OBJECT-TYPE
SYNTAX INTEGER {
other (1), -- not specified by this MIB reject (2), -- route which discards traffic local (3), -- local interface remote (4) -- remote destination
}
MAX-ACCESS read-create STATUS current DESCRIPTION "The type of route. Note that local(3) refers to a route for which the next hop is the final destination; remote(4) refers to a route for which the next hop is not the final destina- tion.
Routes which do not result in traffic forwarding or rejection should not be displayed even if the implementation keeps them stored internally.
reject (2) refers to a route which, if matched, discards the message as unreachable. This is used in some protocols as a means of correctly aggregating routes."
::= { ipCidrRouteEntry 6 }
ipCidrRouteProto 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 isIs (9), -- Dual IS-IS esIs (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 ciscoEigrp (16) -- Cisco EIGRP
}
MAX-ACCESS read-only STATUS current DESCRIPTION "The routing mechanism via which this route was learned. Inclusion of values for gateway rout- ing protocols is not intended to imply that hosts should support those protocols."
::= { ipCidrRouteEntry 7 }
ipCidrRouteAge OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-only STATUS current 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 } ::= { ipCidrRouteEntry 8 }
ipCidrRouteInfo OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-create STATUS current 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 ipCidrRouteProto 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."
ipCidrRouteNextHopAS OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS current DESCRIPTION "The Autonomous System Number of the Next Hop. The semantics of this object are determined by the routing-protocol specified in the route's ipCidrRouteProto value. When this object is unknown or not relevant its value should be set to zero." DEFVAL { 0 } ::= { ipCidrRouteEntry 10 }
ipCidrRouteMetric1 OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS current DESCRIPTION "The primary routing metric for this route. The semantics of this metric are determined by the routing-protocol specified in the route's ipCidrRouteProto value. If this metric is not used, its value should be set to -1." DEFVAL { -1 } ::= { ipCidrRouteEntry 11 }
ipCidrRouteMetric2 OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS current DESCRIPTION "An alternate routing metric for this route. The semantics of this metric are determined by the routing-protocol specified in the route's ipCidrRouteProto value. If this metric is not used, its value should be set to -1." DEFVAL { -1 } ::= { ipCidrRouteEntry 12 }
ipCidrRouteMetric3 OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS current DESCRIPTION "An alternate routing metric for this route. The semantics of this metric are determined by the routing-protocol specified in the route's ipCidrRouteProto value. If this metric is not used, its value should be set to -1." DEFVAL { -1 } ::= { ipCidrRouteEntry 13 }
ipCidrRouteMetric4 OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS current DESCRIPTION "An alternate routing metric for this route. The semantics of this metric are determined by the routing-protocol specified in the route's ipCidrRouteProto value. If this metric is not used, its value should be set to -1." DEFVAL { -1 } ::= { ipCidrRouteEntry 14 }
ipCidrRouteMetric5 OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS current DESCRIPTION "An alternate routing metric for this route. The semantics of this metric are determined by the routing-protocol specified in the route's ipCidrRouteProto value. If this metric is not used, its value should be set to -1." DEFVAL { -1 } ::= { ipCidrRouteEntry 15 }
ipCidrRouteStatus OBJECT-TYPE
SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION "The row status variable, used according to row installation and removal conventions."
::= { ipCidrRouteEntry 16 }
ipForwardNumber OBJECT-TYPE SYNTAX Gauge32 MAX-ACCESS read-only STATUS obsolete 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 -- the autonomous system of the next hop, multiple next hop -- support, and policy routing support.
ipForwardTable OBJECT-TYPE SYNTAX SEQUENCE OF IpForwardEntry MAX-ACCESS not-accessible STATUS obsolete DESCRIPTION
"This entity's IP Routing table."
REFERENCE
"RFC 1213 Section 6.6, The IP Group"
::= { ipForward 2 }
ipForwardEntry OBJECT-TYPE
SYNTAX IpForwardEntry MAX-ACCESS not-accessible STATUS obsolete DESCRIPTION "A particular route to a particular destina- tion, under a particular policy."
INDEX {
ipForwardDest, ipForwardProto, ipForwardPolicy, ipForwardNextHop }
::= { ipForwardTable 1 }
ipForwardDest OBJECT-TYPE
SYNTAX IpAddress MAX-ACCESS read-only STATUS obsolete 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 MAX-ACCESS read-create STATUS obsolete 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- 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 Integer32 MAX-ACCESS read-only STATUS obsolete 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 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."
ipForwardNextHop OBJECT-TYPE
SYNTAX IpAddress MAX-ACCESS read-only STATUS obsolete DESCRIPTION "On remote routes, the address of the next sys- tem en route; Otherwise, 0.0.0.0."
::= { ipForwardEntry 4 }
ipForwardIfIndex OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS obsolete 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
}
MAX-ACCESS read-create STATUS obsolete DESCRIPTION "The type of route. Note that local(3) refers to a route for which the next hop is the final 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
}
MAX-ACCESS read-only STATUS obsolete DESCRIPTION "The routing mechanism via which this route was learned. Inclusion of values for gateway rout- ing protocols is not intended to imply that hosts should support those protocols."
::= { ipForwardEntry 7 }
ipForwardAge OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-only STATUS obsolete 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 MAX-ACCESS read-create STATUS obsolete 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."
::= { ipForwardEntry 9 }
ipForwardNextHopAS OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS obsolete 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 }
ipForwardMetric1 OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS obsolete 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 Integer32 MAX-ACCESS read-create STATUS obsolete 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 Integer32 MAX-ACCESS read-create STATUS obsolete 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 Integer32 MAX-ACCESS read-create STATUS obsolete 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 14 }
ipForwardMetric5 OBJECT-TYPE
SYNTAX Integer32 MAX-ACCESS read-create STATUS obsolete 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 }
RFC 2096 IP Forwarding Table MIB January 19975. Acknowledgements
This work was originally performed by the Router Requirements Working Group at the request of the OSPF Working Group. This update was performed under the auspices of the OSPF Working Group. John Moy of Proteon Incorporated is the chair.
[1] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
"Structure of Management Information for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1442, SNMP Research, Inc., Hughes LAN Systems, Dover Beach Consulting, Inc., Carnegie Mellon University, April 1993.
[2] Galvin, J., and K. McCloghrie, "Administrative Model for
version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1445, Trusted Information Systems, Hughes LAN Systems, April 1993.
[3] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
"Protocol Operations for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1448, SNMP Research, Inc., Hughes LAN Systems, Dover Beach Consulting, Inc., Carnegie Mellon University, April 1993.
[4] McCloghrie, K., and M. Rose, "Management Information Base
for Network Management of TCP/IP-based internets - MIB- II", STD 17, RFC 1213, Hughes LAN Systems, Performance Systems International, March 1991.
[5] Postel, J., "Internet Protocol", STD 5, RFC 791,
USC/Information Sciences Institute, September 1981.
[6] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
"Textual Conventions for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1443, SNMP Research, Inc., Hughes LAN Systems, Dover Beach Consulting, Inc., Carnegie Mellon University, April 1993.
Fred Baker Cisco Systems 519 Lado Drive Santa Barbara, California 93111
Phone: +1 805 681 0115 EMail: fred@cisco.com
Baker Standards Track [Page 21]
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