Network Working Group F. Baker

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, [email protected].

Table of Contents

1 The SNMPv2 Network Management Framework ............... 2
1.1 Object Definitions .................................. 2
2 Overview .............................................. 2
2.1 Textual Conventions ................................. 2
3 Definitions ........................................... 3
3.1 Interface Attributes Database ....................... 3
3.2 Notifications ....................................... 6
4 Security Considerations ............................... 7
5 Authors' Addresses .................................... 8
6 Acknowledgements ...................................... 8
7 References ............................................ 8

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1. The SNMPv2 Network Management Framework

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

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

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

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

o 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

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: [email protected]"
DESCRIPTION
"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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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 }

IntSrvGuaranteedIfEntry ::=
SEQUENCE {
intSrvGuaranteedIfBacklog INTEGER,
intSrvGuaranteedIfDelay INTEGER,
intSrvGuaranteedIfSlack INTEGER,
intSrvGuaranteedIfStatus RowStatus
}

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

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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

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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
DESCRIPTION
"'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
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 }

END

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
EMail: [email protected]

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

Phone: +1 508 692 5875
EMail: [email protected]

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

Phone: +1 408 526 7685
EMail: [email protected]

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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