HTB - Hierarchy Token Bucket


   tc  qdisc  ... dev dev ( parent classid | root) [ handle major: ] htb [
   default minor-id ]

   tc class ... dev dev parent major:[minor] [ classid major:minor  ]  htb
   rate rate [ ceil rate ] burst bytes [ cburst bytes ] [ prio priority ]


   HTB is meant as a more understandable and intuitive replacement for the
   CBQ qdisc in Linux. Both CBQ and HTB help you to control the use of the
   outbound  bandwidth on a given link. Both allow you to use one physical
   link to simulate several slower links and to send  different  kinds  of
   traffic  on  different  simulated  links.  In  both  cases, you have to
   specify how to divide the physical link into simulated links and how to
   decide which simulated link to use for a given packet to be sent.

   Unlike  CBQ,  HTB  shapes  traffic  based  on  the  Token Bucket Filter
   algorithm which does not depend on  interface  characteristics  and  so
   does  not  need  to  know  the  underlying  bandwidth  of  the outgoing


   Shaping works as documented in tc-tbf (8).


   Within the one HTB instance many  classes  may  exist.  Each  of  these
   classes contains another qdisc, by default tc-pfifo(8).

   When  enqueueing  a  packet,  HTB  starts  at the root and uses various
   methods to determine which class should receive the data.

   In the absence of uncommon configuration options, the process is rather
   easy.   At  each  node  we  look for an instruction, and then go to the
   class the instruction refers us to. If the  class  found  is  a  barren
   leaf-node (without children), we enqueue the packet there. If it is not
   yet a leaf node, we do the whole thing over again  starting  from  that

   The  following  actions  are performed, in order at each node we visit,
   until one sends us to another node, or terminates the process.

   (i)    Consult filters attached to the class. If sent to a leafnode, we
          are done.  Otherwise, restart.

   (ii)   If  none  of  the above returned with an instruction, enqueue at
          this node.

   This algorithm makes sure that a packet always ends up somewhere,  even
   while you are busy building your configuration.




   The root of a HTB qdisc class tree has the following parameters:

   parent major:minor | root
          This  mandatory  parameter  determines  the  place  of  the  HTB
          instance, either at the  root  of  an  interface  or  within  an
          existing class.

   handle major:
          Like  all other qdiscs, the HTB can be assigned a handle. Should
          consist only of a major number, followed by a  colon.  Optional,
          but very useful if classes will be generated within this qdisc.

   default minor-id
          Unclassified traffic gets sent to the class with this minor-id.


   Classes have a host of parameters to configure their operation.

   parent major:minor
          Place  of  this class within the hierarchy. If attached directly
          to a qdisc and not to  another  class,  minor  can  be  omitted.

   classid major:minor
          Like  qdiscs,  classes  can  be  named. The major number must be
          equal to the major number of the  qdisc  to  which  it  belongs.
          Optional, but needed if this class is going to have children.

   prio priority
          In  the  round-robin  process,  classes with the lowest priority
          field are tried for packets first. Mandatory.

   rate rate
          Maximum rate this class and all  its  children  are  guaranteed.

   ceil rate
          Maximum  rate  at  which  a  class  can  send, if its parent has
          bandwidth to spare.  Defaults  to  the  configured  rate,  which
          implies no borrowing

   burst bytes
          Amount  of  bytes  that can be burst at ceil speed, in excess of
          the configured rate.  Should be at least as high as the  highest
          burst of all children.

   cburst bytes
          Amount  of bytes that can be burst at 'infinite' speed, in other
          words, as fast as the interface can transmit them.  For  perfect
          evening  out,  should  be  equal  to at most one average packet.
          Should be at  least  as  high  as  the  highest  cburst  of  all


   Due  to  Unix timing constraints, the maximum ceil rate is not infinite
   and may in fact be quite low. On Intel, there are 100 timer events  per
   second,  the  maximum rate is that rate at which 'burst' bytes are sent
   each timer tick.  From this, the minimum burst  size  for  a  specified
   rate  can be calculated. For i386, a 10mbit rate requires a 12 kilobyte
   burst as 100*12kb*8 equals 10mbit.



   HTB website:


   Martin Devera <>. This manpage maintained  by  bert  hubert


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.

Free Software

Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.

Free Books

The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.