The Use of ATM Quality of Service to Support IP over ATM Bruce A. - - PowerPoint PPT Presentation

▶

Apr 07, 2023 397 likes •621 views

The Use of ATM Quality of Service to Support IP over ATM Bruce A. Mah bmah@CS.Berkeley.EDU The Tenet Group University of California at Berkeley T Y O I F S R C E A V A L I I F N O U R L L E E I G H T

SLIDE 1

The Use of ATM Quality of Service to Support IP over ATM Page 1 of 20

The Use of ATM Quality of Service to Support IP over ATM

Bruce A. Mah bmah@CS.Berkeley.EDU The Tenet Group University of California at Berkeley 17th Annual ILP Conference, Berkeley, CA 9 March 1995

H E

N I V E R S I T Y

A L I F O R N I A

8 6 8

E T T H E R E B E L I G H T

SLIDE 2

The Use of ATM Quality of Service to Support IP over ATM Page 2 of 20

Outline

Introduction Using ATM QOS for IP conversations Multiplexing Virtual circuit management Implementation and Evaluation Summary

SLIDE 3

The Use of ATM Quality of Service to Support IP over ATM Page 3 of 20

Environment: A Heterogeneous IP Internet

ATM network provides performance guarantees Internetwork carries a mix of data and multimedia traffic

R H R R H FDDI Ethernet Ethernet S S S ATM Network

SLIDE 4

The Use of ATM Quality of Service to Support IP over ATM Page 4 of 20

IP over ATM

IP layer uses ATM protocol stack as a datalink layer Many commercial and research implementations exist Can we use ATM QOS to improve performance?

ATM AAL5 FDDI Ethernet IP UDP TCP

SLIDE 5

The Use of ATM Quality of Service to Support IP over ATM Page 5 of 20

Research Issues

Using ATM Virtual Circuits for IP

How to map a stream of IP datagrams onto a virtual circuit? What QOS requirements do IP conversations have?

Multiplexing

How and when should multiple conversations share a virtual circuit?

Virtual Circuit Management

When should virtual circuits be created and torn down?

SLIDE 6

The Use of ATM Quality of Service to Support IP over ATM Page 6 of 20

Mapping IP Datagrams onto a Virtual Circuit

“IP Conversation”

A stream of related IP datagrams between common endpoints with some definable set of QOS parameters Hosts and routers use protocol headers to determine conversations Packets of a conversations travel over a single ATM virtual circuit

For example:

All packets for a given telnet connection All NFS packets between a client and its server All ICMP messages between a host pair

SLIDE 7

The Use of ATM Quality of Service to Support IP over ATM Page 7 of 20

Determination of Requirements

Pre-defined per application

For well-known applications (e.g. telnet)

Monitoring traffic

Adapt to bandwidth requirements (e.g. variable-bitrate video)

Explicit signalling

In-band (e.g. IP options) Out-of-band with a signalling protocol (e.g. RCAP, RSVP)

SLIDE 8

The Use of ATM Quality of Service to Support IP over ATM Page 8 of 20

Multiplexing with QOS Considerations

Tradeoff

Protection of individual IP conversations Increased utilization of reserved resources due to statistical multiplexing

SLIDE 9

The Use of ATM Quality of Service to Support IP over ATM Page 9 of 20

Virtual Circuit Per Router Pair

All traffi c between a pair of r outers routed over same virtual circuit Statistical multiplexing of conversations over virtual circuit No protection among conversations sharing a router pair Uses:

Low-bitrate or bursty traffi c (ICMP) Background best-effort traffi c (electr onic mail) R R H H H H

SLIDE 10

The Use of ATM Quality of Service to Support IP over ATM Page 10 of 20

Virtual Circuit Per Conversation

Each IP conversation seen by a router uses a separate virtual circuit IP conversations protected from each other over ATM subnet No statistical multiplexing gain within virtual circuit Uses:

Real-time video Interactive fi le transfer R R H H H H

SLIDE 11

The Use of ATM Quality of Service to Support IP over ATM Page 11 of 20

Virtual Circuit Management with QOS Considerations

Paradigm shift: ATM connections vs. IP datagrams

When to set up and tear down connections for datagrams?

Tradeoff

Long-lived virtual circuits: Tie up resources Short-lived virtual circuits: Connection setup latency and processing

SLIDE 12

The Use of ATM Quality of Service to Support IP over ATM Page 12 of 20

Permanent Virtual Circuits

No connection setup latency Resources always reserved Not flexible enough to handle changes in load Scalability a problem: connections and resources

R R R

O n2 ( )

SLIDE 13

The Use of ATM Quality of Service to Support IP over ATM Page 13 of 20

Switched Virtual Circuits

Establish virtual circuits on demand Tear down connections when not used Connection setup latency incurred

For fi rst packet of conversation For other packets if SVC closed too early

Enhancement: connection caching for other IP conversations

R R R

SLIDE 14

The Use of ATM Quality of Service to Support IP over ATM Page 14 of 20

Implementation and Evaluation

XUNET II: A wide-area ATM backbone (DS-3 between FDDI)

Berkeley LBL Bell Labs Wisconsin UIUC LLNL SNL Rutgers

SLIDE 15

The Use of ATM Quality of Service to Support IP over ATM Page 15 of 20

Completed Work

MBONE Measurements

Video—nv Audio—vat Image distribution—imm

XUNET IP driver modifi ed to distinguish IP conversations

All TCP connections map to unique virtual circuits All UDP streams map to unique virtual circuits

XUNET IP over ATM service enhanced to use SVCs

Virtual circuits created on demand Fixed idle timeout

SLIDE 16

The Use of ATM Quality of Service to Support IP over ATM Page 16 of 20

Video Bitrate (nv 128 Kbps)

Average bitrate (one-second samples) 115 Kbps Peak bitrate (one-second samples) 270 Kbps

50 100 150 200 250 300 500 1000 1500 2000 2500 3000 3500 4000 KBits per second Time in Seconds law.cs.berkeley.edu

SLIDE 17

The Use of ATM Quality of Service to Support IP over ATM Page 17 of 20

XUNET Router TCP Throughput

Preliminary measurements show no performance degradation

5 10 15 20 25 30 35 40 1000 2000 3000 4000 5000 6000 7000 8000 9000 Throughput (Mbps) User Data Payload Size (Bytes) Enhanced XUNET IP Driver Default XUNET IP Driver

SLIDE 18

The Use of ATM Quality of Service to Support IP over ATM Page 18 of 20

Work in Progress

Obtain QOS-guaranteed virtual circuits over XUNET

Scheduling disciplines Signalling support

Formulate IP over ATM strategies

Mapping from IP conversation(s) to QOS-guaranteed virtual circuit Multiplexing policy Virtual circuit setup and teardown policy

SLIDE 19

The Use of ATM Quality of Service to Support IP over ATM Page 19 of 20

Evaluation of Strategies

Performance for IP conversations

End-to-end latency Throughput Setup latency

Overall network performance

Utilization Effi ciency and over head Best-effort performance

SLIDE 20

The Use of ATM Quality of Service to Support IP over ATM Page 20 of 20

The Use of ATM Quality of Service to Support IP over ATM

Bruce A. Mah bmah@CS.Berkeley.EDU The Tenet Group University of California at Berkeley 17th Annual ILP Conference, Berkeley, CA 9 March 1995

Outline

Introduction Using ATM QOS for IP conversations Multiplexing Virtual circuit management Implementation and Evaluation Summary

Environment: A Heterogeneous IP Internet

ATM network provides performance guarantees Internetwork carries a mix of data and multimedia traffic

R H R R H FDDI Ethernet Ethernet S S S ATM Network

IP over ATM

IP layer uses ATM protocol stack as a datalink layer Many commercial and research implementations exist Can we use ATM QOS to improve performance?

ATM AAL5 FDDI Ethernet IP UDP TCP

Research Issues

Using ATM Virtual Circuits for IP

How to map a stream of IP datagrams onto a virtual circuit? What QOS requirements do IP conversations have?

Multiplexing

How and when should multiple conversations share a virtual circuit?

Virtual Circuit Management

When should virtual circuits be created and torn down?

Mapping IP Datagrams onto a Virtual Circuit

“IP Conversation”

A stream of related IP datagrams between common endpoints with some definable set of QOS parameters Hosts and routers use protocol headers to determine conversations Packets of a conversations travel over a single ATM virtual circuit

For example:

All packets for a given telnet connection All NFS packets between a client and its server All ICMP messages between a host pair

Determination of Requirements

Pre-defined per application

For well-known applications (e.g. telnet)

Monitoring traffic

Adapt to bandwidth requirements (e.g. variable-bitrate video)

Explicit signalling

In-band (e.g. IP options) Out-of-band with a signalling protocol (e.g. RCAP, RSVP)

Multiplexing with QOS Considerations

Tradeoff

Protection of individual IP conversations Increased utilization of reserved resources due to statistical multiplexing

Virtual Circuit Per Router Pair

All traffi c between a pair of r outers routed over same virtual circuit Statistical multiplexing of conversations over virtual circuit No protection among conversations sharing a router pair Uses:

Low-bitrate or bursty traffi c (ICMP) Background best-effort traffi c (electr onic mail) R R H H H H

Virtual Circuit Per Conversation

Each IP conversation seen by a router uses a separate virtual circuit IP conversations protected from each other over ATM subnet No statistical multiplexing gain within virtual circuit Uses:

Real-time video Interactive fi le transfer R R H H H H

Virtual Circuit Management with QOS Considerations

Paradigm shift: ATM connections vs. IP datagrams

When to set up and tear down connections for datagrams?

Tradeoff

Long-lived virtual circuits: Tie up resources Short-lived virtual circuits: Connection setup latency and processing

Permanent Virtual Circuits

No connection setup latency Resources always reserved Not flexible enough to handle changes in load Scalability a problem: connections and resources

R R R

O n2 ( )

Switched Virtual Circuits

Establish virtual circuits on demand Tear down connections when not used Connection setup latency incurred

For fi rst packet of conversation For other packets if SVC closed too early

Enhancement: connection caching for other IP conversations

R R R

Implementation and Evaluation

XUNET II: A wide-area ATM backbone (DS-3 between FDDI)

Berkeley LBL Bell Labs Wisconsin UIUC LLNL SNL Rutgers

Completed Work

MBONE Measurements

Video—nv Audio—vat Image distribution—imm

XUNET IP driver modifi ed to distinguish IP conversations

All TCP connections map to unique virtual circuits All UDP streams map to unique virtual circuits

XUNET IP over ATM service enhanced to use SVCs

Virtual circuits created on demand Fixed idle timeout

Video Bitrate (nv 128 Kbps)

Average bitrate (one-second samples) 115 Kbps Peak bitrate (one-second samples) 270 Kbps

50 100 150 200 250 300 500 1000 1500 2000 2500 3000 3500 4000 KBits per second Time in Seconds law.cs.berkeley.edu

XUNET Router TCP Throughput

Preliminary measurements show no performance degradation

5 10 15 20 25 30 35 40 1000 2000 3000 4000 5000 6000 7000 8000 9000 Throughput (Mbps) User Data Payload Size (Bytes) Enhanced XUNET IP Driver Default XUNET IP Driver

Work in Progress

Obtain QOS-guaranteed virtual circuits over XUNET

Scheduling disciplines Signalling support

Formulate IP over ATM strategies

Mapping from IP conversation(s) to QOS-guaranteed virtual circuit Multiplexing policy Virtual circuit setup and teardown policy

Evaluation of Strategies

Performance for IP conversations

End-to-end latency Throughput Setup latency

Overall network performance

Utilization Effi ciency and over head Best-effort performance

Summary

Idea: Use QOS guarantees for an IP-over-ATM service