Network Working Group F. Baker Request for Comments: 2214 Cisco Systems Category: Standards Track J. Krawczyk ArrowPoint Communications A. Sastry Cisco Systems September 1997
Integrated Services Management Information Base Guaranteed Service Extensions 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.
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 the the interface attributes defined in the Guaranteed Service of the Integrated Services Model. Comments should be made to the Integrated Services Working Group, intserv@isi.edu.
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.
Several new data types are introduced as a textual convention in this MIB document. These textual conventions enhance the readability of the specification and can ease comparison with other specifications if appropriate. It should be noted that the introduction of the these textual conventions has no effect on either the syntax nor the semantics of any managed objects. The use of these is merely an artifact of the explanatory method used. Objects defined in terms of one of these methods are always encoded by means of the rules that define the primitive type. Hence, no changes to the SMI or the SNMP are necessary to accommodate these textual conventions which are adopted merely for the convenience of readers and writers in pursuit
Baker, et. al. Standards Track [Page 2]
RFC 2214 IS Guaranteed Service MIB using SMIv2 September 1997
of the elusive goal of clear, concise, and unambiguous MIB documents.
INTEGRATED-SERVICES-GUARANTEED-MIB DEFINITIONS ::= BEGIN
IMPORTS MODULE-IDENTITY, OBJECT-TYPE FROM SNMPv2-SMI RowStatus FROM SNMPv2-TC MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF intSrv FROM INTEGRATED-SERVICES-MIB ifIndex FROM IF-MIB;
-- This MIB module uses the extended OBJECT-TYPE macro as -- defined in [9].
intSrvGuaranteed MODULE-IDENTITY LAST-UPDATED "9511030500Z" -- Thu Aug 28 09:04:22 PDT 1997 ORGANIZATION "IETF Integrated Services Working Group" CONTACT-INFO " Fred Baker Postal: Cisco Systems 519 Lado Drive Santa Barbara, California 93111 Tel: +1 805 681 0115 E-Mail: fred@cisco.com" DESCRIPTION "The MIB module to describe the Guaranteed Service of the Integrated Services Protocol" ::= { intSrv 5 }
-- The Integrated Services Interface Attributes Database -- contains information that is shared with other reservation -- procedures such as ST-II.
intSrvGuaranteedIfTable OBJECT-TYPE SYNTAX SEQUENCE OF IntSrvGuaranteedIfEntry MAX-ACCESS not-accessible STATUS current
Baker, et. al. Standards Track [Page 3]
RFC 2214 IS Guaranteed Service MIB using SMIv2 September 1997
DESCRIPTION "The attributes of the system's interfaces ex- ported by the Guaranteed Service." ::= { intSrvGuaranteedObjects 1 }
intSrvGuaranteedIfEntry OBJECT-TYPE SYNTAX IntSrvGuaranteedIfEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "The reservable attributes of a given inter- face." INDEX { ifIndex } ::= { intSrvGuaranteedIfTable 1 }
intSrvGuaranteedIfBacklog OBJECT-TYPE SYNTAX INTEGER (0..'0FFFFFFF'h) UNITS "bytes" MAX-ACCESS read-create STATUS current DESCRIPTION "The Backlog parameter is the data backlog resulting from the vagaries of how a specific implementation deviates from a strict bit-by- bit service. So, for instance, for packetized weighted fair queueing, Backlog is set to the Maximum Packet Size.
The Backlog term is measured in units of bytes. An individual element can advertise a Backlog value between 1 and 2**28 (a little over 250 megabytes) and the total added over all ele- ments can range as high as (2**32)-1. Should the sum of the different elements delay exceed (2**32)-1, the end-to-end error term should be (2**32)-1." ::= { intSrvGuaranteedIfEntry 1 }
intSrvGuaranteedIfDelay OBJECT-TYPE
Baker, et. al. Standards Track [Page 4]
RFC 2214 IS Guaranteed Service MIB using SMIv2 September 1997
SYNTAX INTEGER (0..'0FFFFFFF'h) UNITS "microseconds" MAX-ACCESS read-create STATUS current DESCRIPTION "The Delay parameter at each service element should be set to the maximum packet transfer delay (independent of bucket size) through the service element. For instance, in a simple router, one might compute the worst case amount of time it make take for a datagram to get through the input interface to the processor, and how long it would take to get from the pro- cessor to the outbound interface (assuming the queueing schemes work correctly). For an Eth- ernet, it might represent the worst case delay if the maximum number of collisions is experi- enced.
The Delay term is measured in units of one mi- crosecond. An individual element can advertise a delay value between 1 and 2**28 (somewhat over two minutes) and the total delay added all elements can range as high as (2**32)-1. Should the sum of the different elements delay exceed (2**32)-1, the end-to-end delay should be (2**32)-1." ::= { intSrvGuaranteedIfEntry 2 }
intSrvGuaranteedIfSlack OBJECT-TYPE SYNTAX INTEGER (0..'0FFFFFFF'h) MAX-ACCESS read-create STATUS current DESCRIPTION "If a network element uses a certain amount of slack, Si, to reduce the amount of resources that it has reserved for a particular flow, i, the value Si should be stored at the network element. Subsequently, if reservation re- freshes are received for flow i, the network element must use the same slack Si without any further computation. This guarantees consisten- cy in the reservation process.
As an example for the use of the slack term, consider the case where the required end-to-end delay, Dreq, is larger than the maximum delay of the fluid flow system. In this, Ctot is the
Baker, et. al. Standards Track [Page 5]
RFC 2214 IS Guaranteed Service MIB using SMIv2 September 1997
sum of the Backlog terms end to end, and Dtot is the sum of the delay terms end to end. Dreq is obtained by setting R=r in the fluid delay formula, and is given by
b/r + Ctot/r + Dtot.
In this case the slack term is
S = Dreq - (b/r + Ctot/r + Dtot).
The slack term may be used by the network ele- ments to adjust their local reservations, so that they can admit flows that would otherwise have been rejected. A service element at an in- termediate network element that can internally differentiate between delay and rate guarantees can now take advantage of this information to lower the amount of resources allocated to this flow. For example, by taking an amount of slack s <= S, an RCSD scheduler [5] can increase the local delay bound, d, assigned to the flow, to d+s. Given an RSpec, (Rin, Sin), it would do so by setting Rout = Rin and Sout = Sin - s.
Similarly, a network element using a WFQ scheduler can decrease its local reservation from Rin to Rout by using some of the slack in the RSpec. This can be accomplished by using the transformation rules given in the previous section, that ensure that the reduced reserva- tion level will not increase the overall end- to-end delay." ::= { intSrvGuaranteedIfEntry 3 }
intSrvGuaranteedIfStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION "'valid' on interfaces that are configured for the Guaranteed Service." ::= { intSrvGuaranteedIfEntry 4 }
-- No notifications are currently defined
-- conformance information
Baker, et. al. Standards Track [Page 6]
RFC 2214 IS Guaranteed Service MIB using SMIv2 September 1997
intSrvGuaranteedCompliance MODULE-COMPLIANCE STATUS current DESCRIPTION "The compliance statement " MODULE -- this module MANDATORY-GROUPS { intSrvGuaranteedIfAttribGroup } ::= { intSrvGuaranteedCompliances 1 }
intSrvGuaranteedIfAttribGroup OBJECT-GROUP OBJECTS { intSrvGuaranteedIfBacklog, intSrvGuaranteedIfDelay, intSrvGuaranteedIfSlack, intSrvGuaranteedIfStatus } STATUS current DESCRIPTION "These objects are required for Systems sup- porting the Guaranteed Service of the Integrat- ed Services Architecture." ::= { intSrvGuaranteedGroups 2 }
The use of an SNMP SET results in an RSVP or Integrated Services reservation under rules that are different compared to if the reservation was negotiated using RSVP. However, no other security considerations exist other than those imposed by SNMP itself.
Baker, et. al. Standards Track [Page 7]
RFC 2214 IS Guaranteed Service MIB using SMIv2 September 1997
[1] Rose, M., Editor, "Management Information Base for Network Management of TCP/IP-based internets", STD 17, RFC 1213, May 1990.
[2] Information processing systems - Open Systems Interconnection - Specification of Abstract Syntax Notation One (ASN.1), International Organization for Standardization. International Standard 8824, (December, 1987).
[3] 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).
Baker, et. al. Standards Track [Page 8]
RFC 2214 IS Guaranteed Service MIB using SMIv2 September 1997