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Internet Draft Robert Ching
John Chiong
Sentient Networks
April 1999
Expires: November 1999
Dynamic Bandwidth Management Using Resource Adjuster Cells
<draft-cc-bw-rac-00.txt>
STATUS OF THIS MEMO:
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Task
Force(IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
And may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft
Shadow Directories can be accessed at http://www.ietf.org/shadow.html.
Distribution of this memo is unlimited.
COPYRIGHT NOTICE:
Copyright (C) The Internet Society (1999). All Rights Reserved.
ABSTRACT:
Dynamic bandwidth management using ATM Resource Adjuster Cells provides
the capability to support fast effective end-to-end bandwidth control
for IP traffic transported over an ATM backbone network. This feature
can open up potential new services for Service Providers to offer
dynamic service levels traffic agreements to their customers. By
offering dynamic service levels, Service Providers can broaden their
scope of service differentiation. For example, using dynamic bandwidth
feature, Service Providers can offer their customers real-time video or multimedia transport capability across the networks.
Using Dynamic Resource Adjuster Cells (DRACs), the network supporting it
can quickly adjust bandwidth without taking down the ATM network
connection and re-establishing it. In a fast changing dynamic
environment, this dynamic adjuster capability makes a difference in
both performance and scalability.
Ching, Chiong <draft-cc-bw-rac-00.txt> [Page 1]
Internet Draft Dynamic Bandwidth Management April 99
The DRACs are based on ATM Traffic Management RM cell format with the
addition of dynamic bandwidth adjustment support parameters. The RAC
parameters can relay bandwidth adjustment parameters to increase or
decrease the bandwidth.
We propose a framework using Dynamic Resource Adjuster Cell that can
relay three parameters, they are bandwidth adjustment, group
identification and priority status. Although DRAC is based on ATM
Resource Management cell format, the same parameters can be used for
non-ATM networks. This paper describes the ATM part only.
In particular, the DRAC contains bandwidth adjustment percentage (BAP)
indicating the percentage increment or decrement from the current
bandwidth, a group identification (GID) that uniquely associates the
connections within a group, and bandwidth bump priority (BBP) that can potentially bump or take bandwidth from lower priority circuits of the
same group.
The goal of this service is to accommodate applications that want to
have more direct control of their network traffic flows.
This draft addresses point-to-point dynamic bandwidth management,
multipoint bandwidth management is left for future study.
Table of Contents
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.0 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.0 Dynamic Bandwidth Management . . . . . . . . . . . . . . . . . 4
3.1 Bandwidth Adjustment Parameter . . . . . . . . . . . . . . 4
3.2 Group Identification . . . . . . . . . . . . . . . . . . . 4
3.3 Bandwidth Bump Priority . . . . . . . . . . . . . . . . . 4
4.0 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.0 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.0 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.0 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
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Internet Draft Dynamic Bandwidth Management April 99
1.0 Introduction
Dynamic bandwidth management using ATM Resource Adjuster Control Cells
provides the capability to support fast effective end-to-end bandwidth
control for IP traffic transported over an ATM backbone network. This
feature can open up potential new services for Service Providers to
offer dynamic service levels traffic agreements to their customers.
By offering dynamic service levels, Service Providers can broaden their
scope of service differentiation. For example, using dynamic bandwidth
feature, Service Providers can offer their customers real-time video or multimedia transport capability across the networks.
Using Dynamic Resource Adjuster Control Cells (DRACs), the nodes
supporting it can quickly adjust bandwidth without taking down the
ATM network connection and re-establishing it. In a fast changing
dynamic environment, this dynamic adjuster capability makes a
difference in both performance and scalability.
The DRACs are based on ATM Traffic Management RM cell format with the
addition of dynamic bandwidth adjustment support parameters. The RAC
parameters can relay bandwidth adjustment parameters to increase or
decrease the bandwidth.
We propose to use Dynamic Resource Adjuster Cell that can relay three
parameters, they are bandwidth adjustment, group identification and
priority status. Although DRAC cells are based on ATM Resource
Management cell format, the same parameters can be used for non-ATM
networks. This paper describes the ATM part only.
In particular, the DRAC contains bandwidth adjustment parameter (BAP)
indicating the percentage increment or decrement from the current
bandwidth, a group identification (GID) that uniquely associates the
connections within a group which is also known as a DRAC stream (see
definition below), and bandwidth bump priority (BBP) that can
potentially bump or take bandwidth from lower priority circuits of the
same group.
The goal of this service is to accommodate applications that want to
have more direct control of their network traffic flows.
This draft addresses point-to-point dynamic bandwidth management,
multi-point bandwidth management is left for future study.
2.0 Definitions
BAP: Bandwidth Adjustment Parameter
BBP: Bandwidth Bump Priority
DRAC: Dynamic Resource Adjuster Control
DRAC Link: A bandwidth transmission medium between two DRAC
Aware Nodes
DRAC ATM Node: A DRAC aware ATM switch
DRAC Stream: A group of DRAC connections with the same traffic
characteristics.
End-system DRAC Gateway: An end system that supports applications'
side bandwidth control and can relay those bandwidth
needs to a DRAC ATM node over a DRAC link.
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Internet Draft Dynamic Bandwidth Management April 99
GID: Group Identification. GID identifies a connection
group.
Intermediate DRAC Gateway: An intermediate node with non-ATM
side bandwidth control and can relay those
bandwidth needs to a DRAC ATM node over a DRAC link.
3.0 Dynamic Bandwidth Management
Transport of IP over ATM network is becoming more common in Service
Providers' networks of today. These IP over ATM networks are
increasingly being used to provide services ranging from LAN
interconnectivity to voice transport. Different ATM class of services
are currently defined that can service Constant Bit Rate (CBR),
real-time Variable Bit Rate (rt-VBR), non-real-time Variable Bit Rate
(nrt-VBR), Available Bit Rate (ABR) and Undefined Bit Rate (UBR).
Although these services can accommodate a large spectrum of IP traffic
types, there are limitations and constraints in effectively supporting
real-time and time-sensitive IP traffic with dynamic bandwidth
characteristics. This proposal adds a capability that can enhance the
support of real-time variable bandwidth IP traffic over ATM. In
particular, the ability of end-to-end support for dynamic bandwidth
control. The notion of this support of end-to-end is based on the
end-system ability to request the change and the transport network
ability to honor the change in a dynamic manner. The following diagram
depicts the components involved for this support.
___ _____ _____ ______ _____ ___
| | | |-----| |_______| |-----| | | |
|ESs|===|EDG |-----|DSR |_______| DSR |-----|EDG |===|ESs|
|___| |_____|-----|_____| |______|-----|_____| |___|
A B C D E
ESs End Systems
EDG End System DRAC Gateway
DSR DRAC Aware Switch-Router
A,E End System to ESDG Links
B,D EDG to DSR Links (EDRAC Links)
C DSR to DSR Links (DDRAC Links)
The way an end-system requests for dynamic bandwidth is not specified
in this specification. Some of the examples are: Bandwidth Control
APIs, Bandwidth Control Policy or based on Bandwidth Configuration.
Note that ESs and EDG can be implemented as one system, or as separate
systems.
When an EDG receives a change of bandwidth request from an ES, the
ESDG will send a DRAC cell that reflects this change to DSR over the
EDRAC link. DSR will process the requested changes and then relay
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Internet Draft Dynamic Bandwidth Management April 99
the bandwidth changes downstream as necessary. The following sections
3.1, 3.2 and 3.3 describe the DRAC cell bandwidth parameters in more
details.
Another type of DRAC gateway is the Intermediate-system DRAC Gateway.
An IDG supports non-ATM side bandwidth usage and decides when to make
bandwidth modification requests to DSR. How IDGs interface within the
non-ATM network or get the bandwidth information is implementation
specifics. One way of doing it will be to support resource reservation
type of protocols.
3.1 Bandwidth Adjustment Parameter (BAP)
This parameter indicates bandwidth adjustment. This parameter is a
percentage increment or decrement based on the current bandwidth for
the connection.
3.2 Group Identification (GID)
This parameter indicates the group that the link belongs to. Typically
this parameter will not change once it is assigned.
3.3 Bandwidth Bump Priority (BBP)
This parameter indicates the relative priority of this connection.
A higher BBP priority can essentially take bandwidth away from lower
priority connections in the same GID. Note that, feedback mechanisms
of bandwidth changes are not currently part of this specification.
The control and potential impact of bandwidth bumping is left to
Applications' control.
4.0 Summary
In summary we make these proposals:
(1) End-system DRAC Gateway, or EDG, supports applications' bandwidth
demand and decides when to make bandwidth modification requests to DSR.
How EDGs interface with applications or get the bandwidth information
is implementation specifics. One way of doing it will be to use dynamic
bandwidth control APIs. EDGs manage and control bandwidth-in-use, and
bandwidth allocation thresholds for applications.
(2) DRAC switch/router, or DSR, supports dynamic bandwidth control
based on DRAC cells. DSR interfaces with EDGs and IDGs at one end, and typcially has trunk interfaces to another DSR. A DSR can aggregate
access side bandwidth over the trunk links.
(3) Intermediate-system DRAC Gateway, or IDG, supports non-ATM side
bandwidth usage and decides when to make bandwidth modification
requests to DSR. How IDGs interface within the non-ATM network or get
the bandwidth information is implementation specifics. One way of doing
it will be to support some form of resource reservation protocol.
(3) DRAC format, based on ATM RM cell and consists of three
parameters, they are Bandwidth Adjustment Parameter (BAP), Group
Identification (GID) and Bandwidth Bump Priority (BBP).
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Internet Draft Dynamic Bandwidth Management April 99
This draft addresses point-to-point QoS resource management, multi-point
QoS resource management is left for future study.
5.0 References
[ADFFT98] Anderson, L., Doolan, P., Feldman, N., Fredette, A., Thomas, B.,
LDP Specification, IETF draft-ietf-mpls-ldp-01.txt, August 1998.
[B98] Bernet, Y., et. al., A Framework for Differentiated Services, IETF
draft-ietf-diffserv-framework-01.txt, October 1998.
[M98] Moy, John, OSPF Version 2, IETF RFC 2328, April 1998.
[RVC99] Rosen, E., Viswanathan, A., Callon, R., Multiprotocol Label
Switching Architecture, IETF draft-ietf-mpls-arch-04.txt, February 1999.
[S95] Steenstrup, M., Editor, Routing in Communications Networks,
Prentice-Hall, 1995.
6.0 Abbreviations
BW Bandwidth
BWIP Bandwidth in Progress
BWOF Bandwidth Offered
BWOV Bandwidth Overflow
DIFFSERV Differentiated Services
HL Heavily Loaded
IETF Internet Engineering Task Force
IP Internet Protocol
LDP Label Distribution Protocol
LSP Label Switched Path
MPLS Multiprotocol Label Switching
OSPF Open Shortest Path First
PSTN Public Switched Telephone Network
QoS Quality of Service
TLV Type/Length/Value
ToS Type of Service
VN Virtual Network
7.0 Authors' Addresses
Robert Ching
John Chiong
Sentient Networks
630 Alder Drive
Milpitas, CA 95035
ching@sentient.com
chiong@sentientnet.com
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