HTB Linux queuing discipline manual - user guide

• 1. Introduction
• 2. Link sharing
• 3. Sharing hierarchy
• 4. Rate ceiling
• 5. Burst
• 6. Priorizing bandwidth share
• 7. Understanding statistics
• 8. Making, debugging and sending error reports

中文链接地址：

http://bbs.chinaunix.net/forum/viewtopic.php?t=520946&show_type=

1. Introduction

This document shows you how to use HTB. Most sections have examples, charts (with measured data) and discussion of particular problems.

This release of HTB should be also much more scalable. See comparison at HTB home page.

Please read: tc tool (not only HTB) uses shortcuts to denote units of rate. kbps means kilobytes and kbit means kilobits ! This is the most FAQ about tc in linux.

2. Link sharing

HTB ensures that the amount of service provided to each class is at least the minimum of the amount it requests and the amount assigned to it. When a class requests less than the amount assigned, the remaining (excess) bandwidth is distributed to other classes which request service.

Also see document about HTB internals - it describes goal above in greater details.

Note: In the literature this is called "borrowing" the excess bandwidth. We use that term below to conform with the literature. We mention, however, that this seems like a bad term since there is no obligation to repay the resource that was "borrowed".

The different kinds of traffic above are represented by classes in HTB. The simplest approach is shown in the picture at the right.
Let's see what commands to use:

tc qdisc add dev eth0 root handle 1: htb default 12

Note: In general (not just for HTB but for all qdiscs and classes in tc), handles are written x:y where x is an integer identifying a qdisc and y is an integer identifying a class belonging to that qdisc. The handle for a qdisc must have zero for its y value and the handle for a class must have a non-zero value for its y value. The "1:" above is treated as "1:0".

tc class add dev eth0 parent 1: classid 1:1 htb rate 100kbps ceil 100kbps 

tc class add dev eth0 parent 1:1 classid 1:10 htb rate 30kbps ceil 100kbps

tc class add dev eth0 parent 1:1 classid 1:11 htb rate 10kbps ceil 100kbps

tc class add dev eth0 parent 1:1 classid 1:12 htb rate 60kbps ceil 100kbps

The first line creates a "root" class, 1:1 under the qdisc 1:. The definition of a root class is one with the htb qdisc as its parent. A root class, like other classes under an htb qdisc allows its children to borrow from each other, but one root class cannot borrow from another. We could have created the other three classes directly under the htb qdisc, but then the excess bandwidth from one would not be available to the others. In this case we do want to allow borrowing, so we have to create an extra class to serve as the root and put the classes that will carry the real data under that. These are defined by the next three lines. The ceil parameter is described below.

Note: Sometimes people ask me why they have to repeat dev eth0 when they have already used handle or parent. The reason is that handles are local to an interface, e.g., eth0 and eth1 could each have classes with handle 1:1.

We also have to describe which packets belong in which class. This is really not related to the HTB qdisc. See the tc filter documentation for details. The commands will look something like this:

文章整理：西部数码--专业提供域名注册、虚拟主机服务
http://www.west263.com
以上信息与文章正文是不可分割的一部分,如果您要转载本文章,请保留以上信息，谢谢!