802.5 SSR MIB: IEEE 802.5 Station Source Routing MIB using SMIv2
SNMP objects for reading and managing the source routes a Token Ring station has learned.
McCloghrie, K., Baker, F., and E. Decker, "IEEE 802.5 Station Source Routing MIB using SMIv2", RFC 1749, DOI 10.17487/RFC1749, December 1994, <https://www.rfc-editor.org/info/rfc1749>.
@misc{rfc1749,
series = {Request for Comments},
number = 1749,
howpublished = {RFC 1749},
publisher = {RFC Editor},
doi = {10.17487/RFC1749},
url = {https://www.rfc-editor.org/info/rfc1749},
author = {K. McCloghrie and F. Baker and E. Decker},
title = {{IEEE 802.5 Station Source Routing MIB using SMIv2}},
pagetotal = 10,
year = 1994,
month = dec,
} RFC text
Contents
Network Working Group K. McCloghrie
Request for Comments: 1749 F. Baker
Updates: 1748 E. Decker
Category: Standards Track cisco Systems, Inc.
December 1994
IEEE 802.5 Station Source Routing MIB using SMIv2
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.
Table of Contents
1. Introduction ............................................. 1
2. The SNMPv2 Network Management Framework .................. 2
2.1 Object Definitions ...................................... 2
3. Overview ................................................. 2
3.1 Source Routing .......................................... 2
3.2 Relationship to RFC 1748 ................................ 3
3.3 Relationship to RFC 1525 ................................ 3
3.4 Static Source Routes .................................... 4
3.5 Destinations on the Local Ring .......................... 4
4. Definitions .............................................. 4
5. Acknowledgements ......................................... 8
6. References ............................................... 8
7. Security Considerations .................................. 9
8. Authors' Addresses ....................................... 10
1. Introduction
This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in the Internet community.
In particular, it describes managed objects used by IEEE 802.5 end-
stations for managing source routes on a Token Ring network where
IEEE source-routing is in use. IEEE source-routing is described in
802.5 Token Ring Access Method and Physical Layer Specifications [8]
and related ISO publications [9, 10, 11].
This memo is an incremental update to RFC 1748 [6]. It is documented
separately from the RFC 1748 solely due to the latter's maturity
within the Internet standardization process.
2. The SNMPv2 Network Management Framework
The SNMPv2 Network Management Framework consists of four major
components. They are:
o RFC 1442 [1] which defines the SMI, the mechanisms used for
describing and naming objects for the purpose of management.
o STD 17, RFC 1213 [2] defines MIB-II, the core set of managed
objects for the Internet suite of protocols.
o RFC 1445 [3] which defines the administrative and other
architectural aspects of the framework.
o RFC 1448 [4] which defines the protocol used for network
access to managed objects.
The Framework permits new objects to be defined for the purpose of
experimentation and evaluation.
2.1. Object Definitions
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 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.
3. Overview
This memo defines a single table: the 802.5 Station Source Routing
Table, which contains the source routes known by a end-station on an
IEEE 802.5 Token Ring network in which IEEE source-routing is in use.
3.1. Source Routing
Source routing extends the 802.5 protocol [8] by assigning a unique
ring number to each ring within the extended LAN, and a bridge number
to each source routing bridge's connection to a ring. A Routing
Information Field (RIF) must be included in frames which need to
traverse multiple rings. The format of the RIF is:
octets octets octets octets
1&2 3&4 5&6 17&18
+------+------+------+-------+------+
| RC | RD | RD | ... | RD |
+------+------+------+-------+------+
<---- 0 to 8 RD fields ---->
The format of the Routing Control (RC) field is:
octet 1 octet 2
+---------------+---------------+
|b b b l l l l l|d f f f 0 0 0 0|
+---------------+---------------+
^ ^ ^ ^
| | | |
Explorer indicator --+ | | +-- Max frame length*
Length of RIF field --+ +-- Direction to use RDs
* Note that the length of the Maximum frame length subfield
has recently been extended to 6 bits.
The format of each Routing Descriptor (RD) field is:
octet 1 octet 2
+---------------+---------------+
|r r r r r r r r r r r r i i i i|
+---------------+---------------+
<---- ring number ----> <----->
^
|
bridge number --+
3.2. Relationship to RFC 1748
RFC 1748 [6], the IEEE 802.5 MIB, defines managed objects used for
interfaces to IEEE 802.5 Token Ring subnetworks. This memo is an
incremental update to RFC 1748, and is documented independently
solely due to the maturity of the definitions contained within RFC
1748.
3.3. Relationship to RFC 1525
RFC 1525 [7] defines the MIB objects specific to source-routing for
source-routing and SRT bridges. This memo defines the MIB objects
specific to source-routing for source-routing end-stations.
3.4. Static Source Routes
It is unclear how many, if any, existing systems allow the creation
or deletion of "static" 802.5 source routes by network management.
However, SNMPv2 SMI defines that the MAX-ACCESS clause as specifying
the maximal level of access which makes "protocol sense". Thus, this
memo provides support for static source routes through the
dot5SrRouteStatus object, but the conformance statements allow for
stations which do not support static source routes, by requiring that
compliant agents only need provide read-access to dot5SrRouteStatus.
3.5. Destinations on the Local Ring
Entries should be included in the dot5SrRouteTable for destination
MAC addresses which are on the same ring as the instrumented 802.5
interface. For such entries, dot5SrRouteDescr has the value of the
zero-length string, and dot5SrRouteControl has the corresponding
value.
4. Definitions
TOKENRING-STATION-SR-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, OBJECT-TYPE
FROM SNMPv2-SMI
TEXTUAL-CONVENTION, RowStatus, MacAddress
FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF
mib-2, ifIndex FROM RFC1213-MIB;
dot5SrMIB MODULE-IDENTITY
LAST-UPDATED "9412161000Z"
ORGANIZATION "IETF Interfaces MIB Working Group"
CONTACT-INFO
" Keith McCloghrie
Postal: Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
US
Phone: +1 408 526 5260
Email: kzm@cisco.com"
DESCRIPTION
"The MIB module for managing source routes in
end-stations on IEEE 802.5 Token Ring networks."
::= { mib-2 42 }
dot5SrMIBObjects OBJECT IDENTIFIER ::= { dot5SrMIB 1 }
SourceRoute ::= TEXTUAL-CONVENTION
DISPLAY-HINT "1x:"
STATUS current
DESCRIPTION
"Represents a Source Route, containing an
embedded sequence of bridge and ring ID's,
as used by 802.5 Source Routing."
REFERENCE "Annex C of ISO/IEC 10038: 1993,
[ANSI/IEEE Std 802.1D, 1993]"
SYNTAX OCTET STRING (SIZE(0..30))
-- The 802.5 Station Source Route Table
--
dot5SrRouteTable OBJECT-TYPE
SYNTAX SEQUENCE OF Dot5SrRouteEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The table of source-routing routes.
This represents the 802.5 RIF database."
::= { dot5SrMIBObjects 1 }
dot5SrRouteEntry OBJECT-TYPE
SYNTAX Dot5SrRouteEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Information on a specific route.
An entry is created whenever a 'Single Path
Explorer' or an 'All Paths Explorer' discovers
a route to a neighbor not currently in the table,
or whenever an 'All Paths Explorer' discovers a
better (e.g., shorter) route than the route currently
stored in the table. This is done on behalf of
any network layer client.
The ifIndex value in the INDEX clause refers to
the value of MIB-II's ifIndex object for the
interface on which the route is in effect."
INDEX { ifIndex, dot5SrRouteDestination }
::= { dot5SrRouteTable 1 }
Dot5SrRouteEntry ::= SEQUENCE {
dot5SrRouteDestination MacAddress,
dot5SrRouteControl OCTET STRING,
dot5SrRouteDescr SourceRoute,
dot5SrRouteStatus RowStatus
}
dot5SrRouteDestination OBJECT-TYPE
SYNTAX MacAddress
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The destination of this route."
::= { dot5SrRouteEntry 2 }
dot5SrRouteControl OBJECT-TYPE
SYNTAX OCTET STRING (SIZE(2))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The value of Routing Control field for this
route."
REFERENCE "Annex C of ISO/IEC 10038: 1993,
[ANSI/IEEE Std 802.1D, 1993]"
::= { dot5SrRouteEntry 3 }
dot5SrRouteDescr OBJECT-TYPE
SYNTAX SourceRoute
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The embedded sequence of bridge and ring ID's
for this route. For destinations on the
local ring, the value of this object is
the zero-length string."
REFERENCE "Annex C of ISO/IEC 10038: 1993,
[ANSI/IEEE Std 802.1D, 1993]"
::= { dot5SrRouteEntry 4 }
dot5SrRouteStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this row. Values of the instances
of dot5SrRouteControl and dot5SrRouteDescr can be
modified while the row's status is 'active."
::= { dot5SrRouteEntry 5 }
-- conformance information
dot5SrConformance OBJECT IDENTIFIER ::= { dot5SrMIB 2 }
dot5SrGroups OBJECT IDENTIFIER ::= { dot5SrConformance 1 }
dot5SrCompliances OBJECT IDENTIFIER ::= { dot5SrConformance 2 }
-- compliance statements
dot5SrCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMPv2 entities
which implement the IEEE 802.5 Station Source Route
MIB."
MODULE -- this module
MANDATORY-GROUPS { dot5SrRouteGroup }
OBJECT dot5SrRouteStatus
SYNTAX INTEGER { active(1) } -- subset of values
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, and only the 'active'
value need be supported."
OBJECT dot5SrRouteControl
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT dot5SrRouteDescr
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
::= { dot5SrCompliances 1 }
-- units of conformance
dot5SrRouteGroup OBJECT-GROUP
OBJECTS { dot5SrRouteControl,
dot5SrRouteDescr,
dot5SrRouteStatus
}
STATUS current
DESCRIPTION
"A collection of objects providing for the management of
source routes in stations on IEEE 802.5 source-routing
networks."
::= { dot5SrGroups 1 }
END
5. Acknowledgements
The need for this MIB module was agreed upon by the members of the
IETF Interfaces Working Group, and the definitions were derived from
experience with enterprise-specific MIBs presented to the Working
Group.
6. References
[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] McCloghrie, K., and M. Rose, Editors, "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.
[3] 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.
[4] 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.
[5] 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.
[6] McCloghrie, K., and E. Decker, "IEEE 802.5 Token Ring MIB using
SMIv2", RFC 1748 cisco Systems, Inc., December 1994.
[7] McCloghrie, K., Decker, E., Langville, P., and A. Rijsinghani,
"Definitions of Managed Objects for Source Routing Bridges", RFC
1525, Hughes LAN Systems, cisco Systems, Inc., Digital Equipment
Corporation, September 1993.
[8] "Token Ring Access Method and Physical Layer Specifications",
IEEE Standard 802.5-1989, 1989.
[9] "Information technology - Local and metropolitan area networks -
Part 5: Token ring access method and physical layer
specifications", ISO/IEC 8802-5, 1992.
[10] "Information technology - Telecommunications and information
exchange between systems - Local area networks - Media access
control (MAC) bridges", ISO/IEC 10038, 1993 [ANSI/IEEE Std
802.1D, 1993 Edition].
[11] "Source Routing Operation by End Systems", ISO/IEC 8802-2 PDAM5.3
(6N7721).
7. Security Considerations
Security issues are not discussed in this memo.
8. Authors' Addresses
Keith McCloghrie
cisco Systems, Inc.
170 West Tasman Drive,
San Jose CA 95134-1706.
Phone: (408) 526-5260
EMail: kzm@cisco.com
Fred Baker
cisco Systems, Inc.
519 Lado Drive
Santa Barbara, CA 93111
Phone: (805) 681-0115
EMail: fred@cisco.com
Eric B. Decker
cisco Systems, Inc.
1525 O'Brien Dr.
Menlo Park, California 94025
Phone: (415) 688-8241
EMail: cire@cisco.com
ISO Plain Language
On this page
§1What This MIB Covers
The memo defines a portion of the Management Information Base, the MIB, for use with network management protocols in the Internet community. In particular it describes managed objects used by IEEE 802.5 end stations for managing source routes on a Token Ring network where IEEE source routing is in use. IEEE source routing itself is described in the 802.5 Token Ring Access Method and Physical Layer Specifications and related ISO publications.
The memo is an incremental update to RFC 1748, the IEEE 802.5 MIB, which defines managed objects for interfaces to IEEE 802.5 Token Ring subnetworks. It is documented separately from RFC 1748 solely because of the latter's maturity within the Internet standardisation process.
This MIB covers one thing: the source routes that a Token Ring station has learned. It was split out from the wider 802.5 MIB only because that document had already been through more of the standardisation process.
§2The SNMPv2 Network Management Framework
The SNMPv2 Network Management Framework has four major components. RFC 1442 defines the SMI, the mechanisms used for describing and naming objects for the purpose of management. STD 17, RFC 1213, defines MIB-II, the core set of managed objects for the Internet suite of protocols. RFC 1445 defines the administrative and other architectural aspects of the framework, and RFC 1448 defines the protocol used for network access to managed objects. The framework permits new objects to be defined for the purpose of experimentation and evaluation.
Managed objects are accessed through a virtual information store, the MIB. Objects in the MIB are defined using the subset of Abstract Syntax Notation One defined in the SMI. Each object type is named by an OBJECT IDENTIFIER, an administratively assigned name, and the object type together with an object instance serves to uniquely identify a specific instantiation of the object. For human convenience a textual string, termed the descriptor, is often used to refer to the object type.
The framework has four parts: a language for naming and describing managed objects, the core MIB of standard objects, the rules for who may do what, and the protocol used to reach the objects over the network. Each object has a numeric name, its object identifier, and an instance of that object stands for one particular value the manager can read or write.
§3Source Routing on a Token Ring
Source routing extends the 802.5 protocol by assigning a unique ring number to each ring within the extended LAN, and a bridge number to each source routing bridge's connection to a ring. A Routing Information Field, the RIF, must be included in frames that need to traverse multiple rings. The RIF begins with a Routing Control field and is followed by up to eight Routing Descriptor fields.
The Routing Control field is two octets. Its first octet holds a three bit explorer indicator and a five bit length of the RIF field. Its second octet holds a one bit direction field, to use the routing descriptors in one direction or the other, and a maximum frame length subfield, whose length has recently been extended to six bits.
Each Routing Descriptor field is two octets as well. The first twelve bits carry the ring number and the last four bits carry the bridge number, so that a frame can be handed from bridge to bridge and ring to ring until it reaches the destination.
Source routing gives every ring in the network a number and every bridge connection a number. When a frame has to cross more than one ring, the sender writes down the route in a field at the front of the frame: first a control byte that says how to read the route, then one pair of bytes per hop, each holding the ring to go to and the bridge to go through.
Routing Control field:
octet 1 octet 2
+---------------+---------------+
|b b b l l l l l|d f f f 0 0 0 0|
+---------------+---------------+
Routing Descriptor field:
octet 1 octet 2
+---------------+---------------+
|r r r r r r r r r r r r i i i i|
+---------------+---------------+
<---- ring number ----> <----->
^
|
bridge number --+§3.4Relations to Other MIBs, Static Routes and Local Ring Destinations
RFC 1525 defines the MIB objects specific to source routing for source routing and SRT bridges, while this memo defines the MIB objects specific to source routing for source routing end stations. The two therefore cover opposite ends of the same mechanism.
The memo notes that it is unclear how many, if any, existing systems allow the creation or deletion of static 802.5 source routes by network management. SNMPv2 SMI defines the MAX-ACCESS clause as specifying the maximal level of access that makes protocol sense. The memo therefore provides support for static source routes through the dot5SrRouteStatus object, but the conformance statements allow for stations which do not support static source routes by requiring that compliant agents only need provide read access to dot5SrRouteStatus.
Entries should be included in the dot5SrRouteTable for destination MAC addresses which are on the same ring as the instrumented 802.5 interface. For such entries, dot5SrRouteDescr has the value of the zero-length string, and dot5SrRouteControl has the corresponding value.
Another document, RFC 1525, manages the bridges that carry source-routed frames; this one manages the stations at the ends. A station that cannot be told to create or delete routes only has to let a manager read the status of each row, and destinations on the station's own ring are listed with an empty route.
§4The 802.5 Station Source Route Table
The module is named dot5SrMIB and is assigned the object identifier mib-2 42. It defines one table, dot5SrRouteTable, which contains the source routes known by an end station on an IEEE 802.5 Token Ring network in which IEEE source routing is in use, and which represents the 802.5 RIF database. Each row is a Dot5SrRouteEntry, indexed by ifIndex and dot5SrRouteDestination, where the ifIndex value refers to the value of MIB-II's ifIndex object for the interface on which the route is in effect.
An entry is created whenever a Single Path Explorer or an All Paths Explorer discovers a route to a neighbour not currently in the table, or whenever an All Paths Explorer discovers a better, for example shorter, route than the one currently stored. This is done on behalf of any network layer client.
The row holds four objects. dot5SrRouteDestination is the destination, of type MacAddress, and is not accessible. dot5SrRouteControl is the value of the Routing Control field for this route, an OCTET STRING of size 2, with read and create access. dot5SrRouteDescr is the embedded sequence of bridge and ring identifiers, of the textual convention SourceRoute, which is an OCTET STRING of size 0 to 30, again with read and create access, and holds the zero-length string for destinations on the local ring. dot5SrRouteStatus is the status of the row, of type RowStatus, with read and create access; the values of the other two objects can be modified while the row's status is active.
The conformance section makes write access optional. The dot5SrRouteStatus object need only support the value active, with a minimum access of read-only, and write access is not required for dot5SrRouteControl or dot5SrRouteDescr either. All three objects form the dot5SrRouteGroup object group, whose description reads: a collection of objects providing for the management of source routes in stations on IEEE 802.5 source-routing networks.
The table has one row for each destination the station knows how to reach. Each row holds the destination's hardware address, the two control bytes that say how to read the route, the route itself as a list of bridge and ring numbers, and a status saying whether the row is in use. A manager can read all of these, and can write the route fields, but only while the row is marked active.
- dot5SrRouteDestinationThe hardware address the route leads to. Read-only to the manager.
- dot5SrRouteControlThe two bytes of the Routing Control field. Read and create.
- dot5SrRouteDescrThe list of bridge and ring numbers, up to 30 bytes. Read and create.
- dot5SrRouteStatusWhether the row is in use. The other two objects may change only while it is active.
§7Security Considerations
The memo has a Security Considerations section, and its whole content is one sentence: security issues are not discussed in this memo.
Nothing in the document describes authentication, access control or confidentiality for the management information it defines. What it does say about who may touch the table is set out in the conformance statements, where write access to the route objects is not required of a compliant agent.
The memo does not discuss security. Its Security Considerations section says only that security issues are not discussed, so nothing in it should be read as a claim that the management objects are protected.