ADSL Bandwidth Management HOWTO, Dan Singletary [free ebook reader for ipad .txt] 📗

ADSL Bandwidth Management HOWTO

Dan Singletary

dvsing@sonicspike.net

Revision History

Revision 1.3 2003-04-07 Revised by: ds

Added links section.

Revision 1.2 2002-09-26 Revised by: ds

Added link to new Email Discussion List. Added small teaser to caveat section

regarding new and improved QoS for Linux designed specifically for ADSL to be

released soon.

Revision 1.1 2002-08-26 Revised by: ds

A few corrections (Thanks to the many that pointed them out!). Added

informational caveat to implementation section.

Revision 1.0 2002-08-21 Revised by: ds

Better control over bandwidth, more theory, updated for 2.4 kernels

Revision 0.1 2001-08-06 Revised by: ds

Initial publication

This document describes how to configure a Linux router to more effectively

manage outbound traffic on an ADSL modem or other device with similar

bandwidth properties (cable modem, ISDN, etc). Emphasis is placed on lowering

the latency for interactive traffic even when the upstream and/or downstream

bandwidth is fully saturated.

Table of Contents

Introduction

1.1. New Versions of This Document

1.2. Email Discussion List

1.3. Disclaimer

1.4. Copyright and License

1.5. Feedback and corrections

Background

2.1. Prerequisites

2.2. Layout

2.3. Packet Queues

How it Works

3.1. Throttling Outbound Traffic with Linux HTB

3.2. Priority Queuing with HTB

3.3. Classifying Outbound Packets with iptables

3.4. A few more tweaks...

3.5. Attempting to Throttle Inbound Traffic

Implementation

4.1. Caveats

4.2. Script: myshaper

Testing the New Queue

OK It Works!! Now What?

Related Links

Introduction

The purpose of this document is to suggest a way to manage outbound traffic

on an ADSL (or cable modem) connection to the Internet. The problem is that

many ADSL lines are limited in the neighborhood of 128kbps for upstream data

transfer. Aggravating this problem is the packet queue in the ADSL modem

which can take 2 to 3 seconds to empty when full. Together this means that

when the upstream bandwidth is fully saturated it can take up to 3 seconds

for any other packets to get out to the Internet. This can cripple

interactive applications such as telnet and multi-player games.

1.1. New Versions of This Document

You can always view the latest version of this document on the World Wide Web

at the URL: [http://www.tldp.org] http://www.tldp.org.

New versions of this document will also be uploaded to various Linux WWW and

FTP sites, including the LDP home page at [http://www.tldp.org] http://

www.tldp.org.

1.2. Email Discussion List

For questions and update information regarding ADSL Bandwidth Management

please subscribe to the ADSL Bandwidth Management email list at [http://

jared.sonicspike.net/mailman/listinfo/adsl-qos] http://jared.sonicspike.net/

mailman/listinfo/adsl-qos.

1.3. Disclaimer

Neither the author nor the distributors, or any other contributor of this

HOWTO are in any way responsible for physical, financial, moral or any other

type of damage incurred by following the suggestions in this text.

1.4. Copyright and License

This document is copyright 2002 by Dan Singletary, and is released under the

terms of the GNU Free Documentation License, which is hereby incorporated by

reference.

1.5. Feedback and corrections

If you have questions or comments about this document, please feel free to

contact the author at [mailto:dvsing@sonicspike.net] dvsing@sonicspike.net.

Background

2.1. Prerequisites

The method outlined in this document should work in other Linux

configurations however it remains untested in any configuration but the

following:

��*�Red Hat Linux 7.3

��*�2.4.18-5 Kernel with QoS Support fully enabled (modules OK) and including

the following kernel patches (which may eventually be included in later kernels): ��+�HTB queue - [http://luxik.cdi.cz/~devik/qos/htb/] http://luxik.cdi.cz /~devik/qos/htb/ Note: it has been reported that kernels since version 2.4.18-3 shipped with Mandrake (8.1, 8.2) have already been patched for HTB. ��+�IMQ device - [http://luxik.cdi.cz/~patrick/imq/] http://luxik.cdi.cz/ ~patrick/imq/

��*�iptables v1.2.6a or later (version of iptables distributed with Red Hat

7.3 is missing the length module)

+---------------------------------------------------------------------------+

| |

| Note: Previous versions of this document specified a method of bandwidth |

| control that involved patching the existing sch-prio queue. It was found |

| later that this patch was entirely unnecessary. Regardless, the newer |

| methods outlined in this document will give you better results (although |

| at the writing of this document 2 kernel patches are now necessary. :) |

| Happy patching.) |

| |

+---------------------------------------------------------------------------+

2.2. Layout

In order to keep things simple, all references to network devices and

configuration in this document will be with respect to the following network

layout diagram:

+----------------------------------------------------------------------------+

| <-- 128kbit/s -------------- <-- 10Mbit --> |

| Internet <--------------------> | ADSL Modem | <-------------------- |

| 1.5Mbit/s --> -------------- | |

| | eth0 |

| V |

| ----------------- |

| | | |

| | Linux Router | |

|