As per Relevance of the word forwarding, we have this rfc below:
Network Working Group F.
Request For Comments: 1354
July 1992
IP Forwarding Table
Status of this
This RFC specifies an IAB standards track protocol for the
community, and requests discussion and suggestions for improvements
Please refer to the current edition of the "IAB Official
Standards" for the standardization state and status of this protocol
Distribution of this memo is unlimited
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
Internet
It is proposed that the ipRouteTable defined by MIB-II (RFC 1213)
deprecated and replaced with this table. This adds the ability
set or display multi-path routes, and varying routes by
management policy
Table of
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
The Internet-standard Network Management Framework consists of
components. They are
RFC 1155 which defines the SMI, the mechanisms used for
and naming objects for the purpose of management. RFC 1212 defines
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more concise description mechanism, which is wholly consistent
the SMI
RFC 1156 which defines MIB-I, the core set of managed objects for
Internet suite of protocols. RFC 1213 defines MIB-II, an
of MIB-I based on implementation experience and new
requirements
RFC 1157 which defines the SNMP, the protocol used for network
to managed objects
The Framework permits new objects to be defined for the purpose
experimentation and evaluation
2.
Managed objects are accessed via a virtual information store,
the Management Information Base or MIB. Objects in the MIB
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,
administratively assigned name, which specifies an object type.
object type together with an object instance serves to
identify a specific instantiation of the object. For
convenience, we often use a textual string, termed the
DESCRIPTOR, to also refer to the object type
The syntax of an object type defines the abstract data
corresponding to that object type. The ASN.1 language is used
this purpose. However, the SMI [3] purposely restricts the ASN.1
constructs which may be used. These restrictions are explicitly
for simplicity
The encoding of an object type is simply how that object type
represented using the object type's syntax. Implicitly tied to
notion of an object type's syntax and encoding is how the object
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
Section 4 contains contains the specification of all object
contained in this MIB module. The object types are defined using
conventions defined in the SMI, as amended by the
specified in [9].
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3.
3.1. Structure of
The IP Forwarding Table is quite analogous to the older
Table. The principal differences are
(1) It is somewhat re-organized, for aesthetic reasons
(2) It has the Next Hop Autonomous System Number,
primarily to the administrators of regional networks
(3) It is instanced by Policy and Next Hop as well as
ultimate destination. Thus, multiple multipath
can be managed, not just a single route, along with
circumstances under which the any given route might
chosen
4.
RFC1354-MIB DEFINITIONS ::=
Gauge,
FROM RFC1155-
mib-2,
FROM RFC1213-
OBJECT-
FROM RFC-1212;
-- This MIB module uses the extended OBJECT-TYPE macro
-- defined in [9].
ipForward OBJECT IDENTIFIER ::= { ip 24 }
ipForwardNumber OBJECT-
SYNTAX
ACCESS read-
STATUS
"The number of current ipForwardTable
that are not invalid."
::= { ipForward 1 }
-- IP Forwarding
-- The IP Forwarding Table obsoletes and replaces the
-- Table current in MIB-I and MIB-II. It adds knowledge
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-- the autonomous system of the next hop, multiple next
-- support, and policy routing support
ipForwardTable OBJECT-
SYNTAX SEQUENCE OF
ACCESS not-
STATUS
"This entity's IP Routing table."
"RFC 1213 Section 6.6, The IP Group
::= { ipForward 2 }
ipForwardEntry OBJECT-
SYNTAX
ACCESS not-
STATUS
"A particular route to a particular destina
tion, under a particular policy."
INDEX {
ipForwardDest
ipForwardProto
ipForwardPolicy
}
::= { ipForwardTable 1 }
IpForwardEntry ::=
SEQUENCE {
IpAddress
IpAddress
INTEGER
IpAddress
INTEGER
INTEGER
INTEGER
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INTEGER
OBJECT IDENTIFIER
INTEGER
ipForwardMetric
INTEGER
ipForwardMetric
INTEGER
ipForwardMetric
INTEGER
ipForwardMetric
INTEGER
ipForwardMetric
}
ipForwardDest OBJECT-
SYNTAX
ACCESS read-
STATUS
"The destination IP address of this route.
entry with a value of 0.0.0.0 is considered
default route
This object may not take a Multicast (Class D
address value
Any assignment (implicit or otherwise) of
instance of this object to a value x must
rejected if the bitwise logical-AND of x
the value of the corresponding instance of
ipForwardMask object is not equal to x."
::= { ipForwardEntry 1 }
ipForwardMask OBJECT-
SYNTAX
ACCESS read-
STATUS
"Indicate the mask to be logical-ANDed with
destination address before being compared
the value in the ipForwardDest field.
those systems that do not support
subnet masks, an agent constructs the value
the ipForwardMask by reference to the IP Ad
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dress Class
Any assignment (implicit or otherwise) of
instance of this object to a value x must
rejected if the bitwise logical-AND of x
the value of the corresponding instance of
ipForwardDest object is not equal to ipForward
Dest."
DEFVAL { '00000000'h } -- 0.0.0.0
::= { ipForwardEntry 2 }
-- The following convention is included for
-- of TOS Field contents. At this time, the Host
-- and the Router Requirements documents disagree on the
-- of the TOS field. This mapping describes the
-- Requirements mapping, and leaves room to widen the TOS
-- without impact to fielded systems
ipForwardPolicy OBJECT-
SYNTAX
ACCESS read-
STATUS
"The general set of conditions that would
the selection of one multipath route (set
next hops for a given destination) is
to as 'policy'.
Unless the mechanism indicated by ipForwardPro
to specifies otherwise, the policy specifier
the IP TOS Field. The encoding of IP TOS is
specified by the following convention.
indicates the default path if no more
policy applies
+-----+-----+-----+-----+-----+-----+-----+-----+
| | | |
| PRECEDENCE | TYPE OF SERVICE | 0 |
| | | |
+-----+-----+-----+-----+-----+-----+-----+-----+
IP TOS IP
Field Policy Field
Contents Code Contents
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
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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
this object or must implement an integer
instanced policy table for which this object'
value acts as an index."
::= { ipForwardEntry 3 }
ipForwardNextHop OBJECT-
SYNTAX
ACCESS read-
STATUS
"On remote routes, the address of the next sys
tem en route; Otherwise, 0.0.0.0."
::= { ipForwardEntry 4 }
ipForwardIfIndex OBJECT-
SYNTAX
ACCESS read-
STATUS
"The ifIndex value which identifies the
interface through which the next hop of
route should be reached."
DEFVAL { 0 }
::= { ipForwardEntry 5 }
ipForwardType OBJECT-
SYNTAX INTEGER {
other (1), -- not specified by this
invalid (2), -- logically
local (3), -- local
remote (4) -- remote
}
ACCESS read-
STATUS
"The type of route. Note that local(3)
to a route for which the next hop is the
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destination; remote(4) refers to a route
which the next hop is not the final destina
tion
Setting this object to the value invalid(2)
the effect of invalidating the
entry in the ipForwardTable object. That is
it effectively disassociates the
identified with said entry from the route iden
tified with said entry. It is
implementation-specific matter as to
the agent removes an invalidated entry from
table. Accordingly, management stations
be prepared to receive tabular information
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-
SYNTAX INTEGER {
other (1), -- not
local (2), -- local
netmgmt (3), -- static
icmp (4), -- result of ICMP
-- the following are all
-- routing
egp (5), -- Exterior Gateway
ggp (6), -- Gateway-Gateway
hello (7), -- FuzzBall
rip (8), -- Berkeley RIP or RIP-
is-is (9), -- Dual IS-
es-is (10), -- ISO 9542
ciscoIgrp (11), -- Cisco
bbnSpfIgp (12), -- BBN SPF
ospf (13), -- Open Shortest Path
bgp (14), -- Border Gateway
idpr (15) -- InterDomain Policy
}
ACCESS read-
STATUS
"The routing mechanism via which this route
learned. Inclusion of values for gateway rout
ing protocols is not intended to imply
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hosts should support those protocols."
::= { ipForwardEntry 7 }
ipForwardAge OBJECT-
SYNTAX
ACCESS read-
STATUS
"The number of seconds since this route
last updated or otherwise determined to
correct. Note that no semantics of `too old
can be implied except through knowledge of
routing protocol by which the route
learned."
DEFVAL { 0 }
::= { ipForwardEntry 8 }
ipForwardInfo OBJECT-
SYNTAX OBJECT
ACCESS read-
STATUS
"A reference to MIB definitions specific to
particular routing protocol which is responsi
ble for this route, as determined by the
specified in the route's ipForwardProto value
If this information is not present, its
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
generate and recognize this value."
DEFVAL { { 0 0 } } -- 0.0
::= { ipForwardEntry 9 }
ipForwardNextHopAS OBJECT-
SYNTAX
ACCESS read-
STATUS
"The Autonomous System Number of the Next Hop
When this is unknown or not relevant to
protocol indicated by ipForwardProto, zero."
DEFVAL { 0 }
::= { ipForwardEntry 10 }
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ipForwardMetric1 OBJECT-
SYNTAX
ACCESS read-
STATUS
"The primary routing metric for this route
The semantics of this metric are determined
the routing-protocol specified in the route'
ipForwardProto value. If this metric is
used, its value should be set to -1."
DEFVAL { -1 }
::= { ipForwardEntry 11 }
ipForwardMetric2 OBJECT-
SYNTAX
ACCESS read-
STATUS
"An alternate routing metric for this route
The semantics of this metric are determined
the routing-protocol specified in the route'
ipForwardProto value. If this metric is
used, its value should be set to -1."
DEFVAL { -1 }
::= { ipForwardEntry 12 }
ipForwardMetric3 OBJECT-
SYNTAX
ACCESS read-
STATUS
"An alternate routing metric for this route
The semantics of this metric are determined
the routing-protocol specified in the route'
ipForwardProto value. If this metric is
used, its value should be set to -1."
DEFVAL { -1 }
::= { ipForwardEntry 13 }
ipForwardMetric4 OBJECT-
SYNTAX
ACCESS read-
STATUS
"An alternate routing metric for this route
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The semantics of this metric are determined
the routing-protocol specified in the route'
ipForwardProto value. If this metric is
used, its value should be set to -1."
DEFVAL { -1 }
::= { ipForwardEntry 14 }
ipForwardMetric5 OBJECT-
SYNTAX
ACCESS read-
STATUS
"An alternate routing metric for this route
The semantics of this metric are determined
the routing-protocol specified in the route'
ipForwardProto value. If this metric is
used, its value should be set to -1."
DEFVAL { -1 }
::= { ipForwardEntry 15 }
5.
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)
significant comments on it, and it is better for their input
6.
[1] Cerf, V., "IAB Recommendations for the Development of
Network Management Standards", RFC 1052, NRI, April 1988.
[2] Cerf, V., "Report of the Second Ad Hoc Network Management
Group", RFC 1109, NRI, August 1989.
[3] Rose M., and K. McCloghrie, "Structure and Identification
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
Network Management of TCP/IP-based internets", RFC 1156,
LAN Systems, Performance Systems International, May 1990.
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RFC 1354 IP Forwarding Table MIB July 1992
[5] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "
Network Management Protocol", RFC 1157, SNMP Research
Performance Systems International, Performance
International, MIT Laboratory for Computer Science, May 1990.
[6] McCloghrie K., and M. Rose, Editors, "Management
Base for Network Management of TCP/IP-based internets",
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,
Standard 8824, December 1987.
[8] Information processing systems - Open Systems Interconnection -
Specification of Basic Encoding Rules for Abstract Notation
(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
Base for Network Management of TCP/IP-based internets",
1213, Performance Systems International, March 1991.
[11] Baker, F., and R. Coltun, "OSPF Version 2 Management
Base", RFC 1253, ACC, Computer Science Center, August 1991.
7. Security
Security issues are not discussed in this memo
8. Author's
Fred
Advanced Computer
315 Bollay
Santa Barbara, CA 93117-6014
Phone: (805) 685-4455
EMail: fbaker@acc.
Baker [Page 12]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
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