Network Working Group                                       F. Baker
Request for Comments: 2214                             Cisco Systems
Category: Standards Track                                J. Krawczyk
                                           ArrowPoint Communications
                                                           A. Sastry
                                                       Cisco Systems
                                                      September 1997
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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.


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,

Table of Contents

1 The SNMPv2 Network Management Framework
1.1 Object Definitions
2 Overview
2.1 Textual Conventions
3 Definitions
3.1 Interface Attributes Database
3.2 Notifications
4 Security Considerations
5 Authors' Addresses
6 Acknowledgements
7 References

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1. The SNMPv2 Network Management Framework

The SNMPv2 Network Management Framework consists of four major components. They are:

  • RFC 1441 which defines the SMI, the mechanisms used for describing and naming objects for the purpose of

  • STD 17, RFC 1213 defines MIB-II, the core set of managed objects for the Internet suite of protocols.

  • RFC 1445 which defines the administrative and other architectural aspects of the framework.

  • RFC 1448 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.

1.1. 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.

2. Overview

2.1. Textual Conventions

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

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of the elusive goal of clear, concise, and unambiguous MIB documents.

3. Definitions



            RowStatus                                FROM SNMPv2-TC
            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
       "The MIB module to describe the Guaranteed Service of
       the Integrated Services Protocol"
    ::= { intSrv 5 }

intSrvGuaranteedObjects OBJECT IDENTIFIER
                                 ::= { intSrvGuaranteed 1 }
intSrvGuaranteedNotifications    OBJECT IDENTIFIER
                                 ::= { intSrvGuaranteed 2 }
intSrvGuaranteedConformance      OBJECT IDENTIFIER
                                 ::= { intSrvGuaranteed 3 }

-- 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

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"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
           "The reservable attributes of  a  given  inter-
       INDEX { ifIndex }
       ::= { intSrvGuaranteedIfTable 1 }

IntSrvGuaranteedIfEntry ::=
intSrvGuaranteedIfBacklog INTEGER,
        intSrvGuaranteedIfDelay   INTEGER,
        intSrvGuaranteedIfSlack   INTEGER,
        intSrvGuaranteedIfStatus  RowStatus

intSrvGuaranteedIfBacklog OBJECT-TYPE

        SYNTAX      INTEGER (0..'0FFFFFFF'h)
        UNITS       "bytes"
        MAX-ACCESS  read-create
        STATUS      current
           "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

       ::= { intSrvGuaranteedIfEntry 1 }

intSrvGuaranteedIfDelay OBJECT-TYPE

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        SYNTAX      INTEGER (0..'0FFFFFFF'h)
        UNITS       "microseconds"
        MAX-ACCESS  read-create
        STATUS      current
           "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-

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
           "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

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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
           "'valid' on interfaces that are configured  for
           the Guaranteed Service."
       ::= { intSrvGuaranteedIfEntry 4 }

-- No notifications are currently defined

-- conformance information

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intSrvGuaranteedGroups OBJECT IDENTIFIER
                            ::= { intSrvGuaranteedConformance 1 }
intSrvGuaranteedCompliances OBJECT IDENTIFIER
                            ::= { intSrvGuaranteedConformance 2 }

-- compliance statements

intSrvGuaranteedCompliance MODULE-COMPLIANCE
STATUS current
"The compliance statement "
MODULE -- this module

       ::= { intSrvGuaranteedCompliances 1 }

intSrvGuaranteedIfAttribGroup OBJECT-GROUP
STATUS current
"These objects are required for Systems sup-
porting the Guaranteed Service of the Integrat-
ed Services Architecture."

       ::= { intSrvGuaranteedGroups 2 }


4. Security Considerations

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.

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5. Authors' Addresses

Fred Baker
Postal: Cisco Systems
519 Lado Drive
Santa Barbara, California 93111

Phone: +1 805 681 0115

John Krawczyk
Postal: ArrowPoint Communications
235 Littleton Road
Westford, Massachusetts 01886

Phone: +1 508 692 5875

Arun Sastry
Postal: Cisco Systems
210 W. Tasman Drive
San Jose, California 95314

Phone: +1 408 526 7685

6. Acknowledgements

This document was produced by the Integrated Services Working Group.

7. References

[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).

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