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<refentry>
  <refmeta>
    <refentrytitle>shorewall-tcclasses</refentrytitle>

    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>tcclasses</refname>

    <refpurpose>Shorewall file to define HTB classes</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>/etc/shorewall/tcclasses</command>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>A note on the <emphasis>rate</emphasis>/bandwidth definitions used
    in this file:</para>

    <itemizedlist>
      <listitem>
        <para>don't use a space between the integer value and the unit: 30kbit
        is valid while 30 kbit is NOT.</para>
      </listitem>

      <listitem>
        <para>you can use one of the following units:</para>

        <variablelist>
          <varlistentry>
            <term><emphasis role="bold">kpbs</emphasis></term>

            <listitem>
              <para>Kilobytes per second.</para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term><emphasis role="bold">mbps</emphasis></term>

            <listitem>
              <para>Megabytes per second.</para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term><emphasis role="bold">kbit</emphasis></term>

            <listitem>
              <para>Kilobits per second.</para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term><emphasis role="bold">mbit</emphasis></term>

            <listitem>
              <para>Megabits per second.</para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term><emphasis role="bold">bps</emphasis> or <emphasis
            role="bold">number</emphasis></term>

            <listitem>
              <para>Bytes per second.</para>
            </listitem>
          </varlistentry>
        </variablelist>
      </listitem>

      <listitem>
        <para>if you want the values to be calculated for you depending on the
        output bandwidth setting defined for an interface in tcdevices, you
        can use expressions like the following:</para>

        <variablelist>
          <varlistentry>
            <term>full/3</term>

            <listitem>
              <para>causes the bandwidth to be calculated as 1/3 of the full
              outgoing speed that is defined.</para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>full*9/10</term>

            <listitem>
              <para>will set this bandwidth to 9/10 of the full
              bandwidth</para>
            </listitem>
          </varlistentry>
        </variablelist>

        <para>Note that in a sub-class (a class that has a specified parent
        class), full refers to the RATE or CEIL of the parent class rather
        than to the OUT-BANDWIDTH of the device.</para>

        <para>DO NOT add a unit to the rate if it is calculated !</para>
      </listitem>
    </itemizedlist>

    <para>The columns in the file are as follows.</para>

    <variablelist>
      <varlistentry>
        <term><emphasis role="bold">INTERFACE</emphasis> -
        <emphasis>interface</emphasis>[[:<emphasis>parent</emphasis>]:<emphasis>class</emphasis>]</term>

        <listitem>
          <para>Name of <emphasis>interface</emphasis>. Each interface may be
          listed only once in this file. You may NOT specify the name of an
          alias (e.g., eth0:0) here; see <ulink
          url="http://www.shorewall.net/FAQ.htm#faq18">http://www.shorewall.net/FAQ.htm#faq18</ulink></para>

          <para>You may specify the interface number rather than the interface
          name. If the <emphasis role="bold">classify</emphasis> option is
          given for the interface in <ulink
          url="shorewall-tcdevices.html">shorewall-tcdevices</ulink>(5), then
          you must also specify an interface class (an integer that must be
          unique within classes associated with this interface). If the
          classify option is not given, you may still specify a
          <emphasis>class</emphasis> or you may have Shorewall generate a
          class number from the MARK value. Interface numbers and class
          numbers are always assumed to be specified in hex.</para>

          <para>You may NOT specify wildcards here, e.g. if you have multiple
          ppp interfaces, you need to put them all in here!</para>

          <para>Please note that you can only use interface names in here that
          have a bandwidth defined in the <ulink
          url="shorewall-tcdevices.html">shorewall-tcdevices</ulink>(5)
          file.</para>

          <para>Normally, all classes defined here are sub-classes of a root
          class that is implicitly defined from the entry in <ulink
          url="shorewall-tcdevices.html">shorewall-tcdevices</ulink>(5). You
          can establish a class hierarchy by specifying a
          <emphasis>parent</emphasis> class -- the number of a class that you
          have previously defined. The sub-class may borrow unused bandwidth
          from its parent.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">MARK</emphasis> -
        {-|<emphasis>value</emphasis>}</term>

        <listitem>
          <para>The mark <emphasis>value</emphasis> which is an integer in the
          range 1-255. You set mark values in the <ulink
          url="shorewall-tcrules.html">shorewall-tcrules</ulink>(5) file,
          marking the traffic you want to fit in the classes defined in here.
          Must be specified as '-' if the <emphasis
          role="bold">classify</emphasis> option is given for the interface in
          <ulink
          url="shorewall-tcdevices.html">shorewall-tcdevices</ulink>(5)</para>

          <para>You can use the same marks for different interfaces.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">RATE</emphasis> -
        <emphasis>rate</emphasis>[:<emphasis>dmax</emphasis>[:<emphasis>umax</emphasis>]]</term>

        <listitem>
          <para>The minimum bandwidth this class should get, when the traffic
          load rises. If the sum of the rates in this column exceeds the
          INTERFACE's OUT-BANDWIDTH, then the OUT-BANDWIDTH limit may not be
          honored. Similarly, if the sum of the rates of sub-classes of a
          class exceed the CEIL of the parent class, things don't work
          well.</para>

          <para>When using the HFSC queuing discipline, leaf classes may
          specify <replaceable>dmax</replaceable>, the maximum delay in
          milliseconds that the first queued packet for this class should
          experience. May be expressed as an integer, optionally followed by
          'ms' with no intervening white space (e.g., 10ms).</para>

          <para>HFSC leaf classes may also specify
          <replaceable>umax</replaceable>, the largest packet expected in this
          class. May be expressed as an integer. The unit of measure is
          <emphasis>bytes</emphasis> and the integer may be optionally
          followed by 'b' with no intervening white space (e.g., 800b).
          <replaceable>umax</replaceable> may only be given if
          <replaceable>dmax</replaceable> is also given.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">CEIL</emphasis> -
        <emphasis>rate</emphasis></term>

        <listitem>
          <para>The maximum bandwidth this class is allowed to use when the
          link is idle. Useful if you have traffic which can get full speed
          when more needed services (e.g. ssh) are not used.</para>

          <para>You can use the value <emphasis role="bold">full</emphasis> in
          here for setting the maximum bandwidth to the RATE of the parent
          class, or the OUT-BANDWIDTH of the device if there is no parent
          class.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">PRIORITY</emphasis> -
        <emphasis>priority</emphasis></term>

        <listitem>
          <para>The <emphasis>priority</emphasis> in which classes will be
          serviced by the packet shaping scheduler and also the priority in
          which bandwidth in excess of the rate will be given to each
          class.</para>

          <para>Higher priority classes will experience less delay since they
          are serviced first. Priority values are serviced in ascending order
          (e.g. 0 is higher priority than 1).</para>

          <para>Classes may be set to the same priority, in which case they
          will be serviced as equals.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">OPTIONS</emphasis> (Optional) -
        [<emphasis>option</emphasis>[<emphasis
        role="bold">,</emphasis><emphasis>option</emphasis>]...]</term>

        <listitem>
          <para>A comma-separated list of options including the
          following:</para>

          <variablelist>
            <varlistentry>
              <term><emphasis role="bold">default</emphasis></term>

              <listitem>
                <para>This is the default class for that interface where all
                traffic should go, that is not classified otherwise.</para>

                <para></para>

                <note>
                  <para>You must define <emphasis
                  role="bold">default</emphasis> for exactly one class per
                  interface.</para>
                </note>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis
              role="bold">tos=0x</emphasis><emphasis>value</emphasis>[/0x<emphasis>mask</emphasis>]
              (mask defaults to 0xff)</term>

              <listitem>
                <para>This lets you define a classifier for the given
                <emphasis>value</emphasis>/<emphasis>mask</emphasis>
                combination of the IP packet's TOS/Precedence/DiffSrv octet
                (aka the TOS byte).</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis
              role="bold">tos-</emphasis><emphasis>tosname</emphasis></term>

              <listitem>
                <para>Aliases for the following TOS octet value and mask
                encodings. TOS encodings of the "TOS byte" have been
                deprecated in favor of diffserve classes, but programs like
                ssh, rlogin, and ftp still use them.</para>

                <programlisting>        <emphasis role="bold">tos-minimize-delay</emphasis>       0x10/0x10
        <emphasis role="bold">tos-maximize-throughput</emphasis>  0x08/0x08
        <emphasis role="bold">tos-maximize-reliability</emphasis> 0x04/0x04
        <emphasis role="bold">tos-minimize-cost</emphasis>        0x02/0x02
        <emphasis role="bold">tos-normal-service</emphasis>       0x00/0x1e</programlisting>

                <note>
                  <para>Each of these options is only valid for ONE class per
                  interface.</para>
                </note>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">tcp-ack</emphasis></term>

              <listitem>
                <para>If defined, causes a tc filter to be created that puts
                all tcp ack packets on that interface that have a size of
                &lt;=64 Bytes to go in this class. This is useful for speeding
                up downloads. Please note that the size of the ack packets is
                limited to 64 bytes because we want only packets WITHOUT
                payload to match.</para>

                <para></para>

                <note>
                  <para>This option is only valid for ONE class per
                  interface.</para>
                </note>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis
              role="bold">occurs</emphasis>=<emphasis>number</emphasis></term>

              <listitem>
                <para>Typically used with an IPMARK entry in tcrules. Causes
                the rule to be replicated for a total of
                <emphasis>number</emphasis> rules. Each rule has a
                successively class number and mark value.</para>

                <para>When 'occurs' is used:</para>

                <itemizedlist>
                  <listitem>
                    <para>The associated device may not have the 'classify'
                    option.</para>
                  </listitem>

                  <listitem>
                    <para>The class may not be the default class.</para>
                  </listitem>

                  <listitem>
                    <para>The class may not have any 'tos=' options (including
                    'tcp-ack').</para>
                  </listitem>

                  <listitem>
                    <para>The class should not specify a MARK value. If one is
                    specified, it will be ignored with a warning
                    message.</para>
                  </listitem>
                </itemizedlist>

                <para>The 'RATE' and 'CEIL' parameters apply to each instance
                of the class. So the total RATE represented by an entry with
                'occurs' will be the listed RATE multiplied by
                <emphasis>number</emphasis>. For additional information, see
                <ulink url="shorewall-tcrules.html">tcrules</ulink>
                (5).</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>flow=<emphasis>keys</emphasis></term>

              <listitem>
                <para>Shorewall attaches an SFQ queuing discipline to each
                leaf HTB class. SFQ ensures that each
                <firstterm>flow</firstterm> gets equal access to the
                interface. The default definition of a flow corresponds
                roughly to a Netfilter connection. So if one internal system
                is running BitTorrent, for example, it can have lots of
                'flows' and can thus take up a larger share of the bandwidth
                than a system having only a single active connection. The
                <option>flow</option> classifier (module cls_flow) works
                around this by letting you define what a 'flow' is. The
                clasifier must be used carefully or it can block off all
                traffic on an interface! The flow option can be specified for
                an HTB leaf class (one that has no sub-classes). We recommend
                that you use the following:</para>

                <simplelist>
                  <member>Shaping internet-bound traffic:
                  flow=nfct-src</member>

                  <member>Shaping traffic bound for your local net:
                  flow=dst</member>
                </simplelist>

                <para>These will cause a 'flow' to consists of the traffic
                to/from each internal system.</para>

                <para>When more than one key is give, they must be enclosed in
                parenthesis and separated by commas.</para>

                <para>To see a list of the possible flow keys, run this
                command:</para>

                <blockquote>
                  <para><command>tc filter add flow help</command></para>
                </blockquote>

                <para>Those that begin with "nfct-" are Netfilter connection
                tracking fields. As shown above, we recommend flow=nfct-src;
                that means that we want to use the source IP address
                <emphasis>before NAT</emphasis> as the key.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>pfifo</term>

              <listitem>
                <para>When specified for a leaf class, the pfifo queing
                discipline is applied to the class rather than the sfq queuing
                discipline.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>limit=<emphasis>number</emphasis></term>

              <listitem>
                <para>Added in Shorewall 4.4.3. When specified for a leaf
                class, determines the maximum number of packets that may be
                queued within the class. The <emphasis>number</emphasis> must
                be &gt; 2 and &lt;=128. If not specified, the value 127 is
                assumed.</para>
              </listitem>
            </varlistentry>
          </variablelist>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Examples</title>

    <variablelist>
      <varlistentry>
        <term>Example 1:</term>

        <listitem>
          <para>Suppose you are using PPP over Ethernet (DSL) and ppp0 is the
          interface for this. You have 4 classes here, the first you can use
          for voice over IP traffic, the second interactive traffic (e.g.
          ssh/telnet but not scp), the third will be for all unclassified
          traffic, and the forth is for low priority traffic (e.g.
          peer-to-peer).</para>

          <para>The voice traffic in the first class will be guaranteed a
          minimum of 100kbps and always be serviced first (because of the low
          priority number, giving less delay) and will be granted excess
          bandwidth (up to 180kbps, the class ceiling) first, before any other
          traffic. A single VOIP stream, depending upon codecs, after
          encapsulation, can take up to 80kbps on a PPOE/DSL link, so we pad a
          little bit just in case. (TOS byte values 0xb8 and 0x68 are DiffServ
          classes EF and AFF3-1 respectively and are often used by VOIP
          devices).</para>

          <para>Interactive traffic (tos-minimum-delay) and TCP acks (and ICMP
          echo traffic if you use the example in tcrules) and any packet with
          a mark of 2 will be guaranteed 1/4 of the link bandwidth, and may
          extend up to full speed of the link.</para>

          <para>Unclassified traffic and packets marked as 3 will be
          guaranteed 1/4th of the link bandwidth, and may extend to the full
          speed of the link.</para>

          <para>Packets marked with 4 will be treated as low priority packets.
          (The tcrules example marks p2p traffic as such.) If the link is
          congested, they're only guaranteed 1/8th of the speed, and even if
          the link is empty, can only expand to 80% of link bandwidth just as
          a precaution in case there are upstream queues we didn't account
          for. This is the last class to get additional bandwidth and the last
          to get serviced by the scheduler because of the low priority.</para>

          <programlisting>        #INTERFACE  MARK  RATE    CEIL      PRIORITY    OPTIONS
        ppp0        1     100kbit 180kbit   1           tos=0x68/0xfc,tos=0xb8/0xfc
        ppp0        2     full/4  full      2           tcp-ack,tos-minimize-delay
        ppp0        3     full/4  full      3           default
        ppp0        4     full/8  full*8/10 4</programlisting>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>FILES</title>

    <para>/etc/shorewall/tcclasses</para>
  </refsect1>

  <refsect1>
    <title>See ALSO</title>

    <para><ulink
    url="http://shorewall.net/traffic_shaping.htm">http://shorewall.net/traffic_shaping.htm</ulink></para>

    <para>shorewall(8), shorewall-accounting(5), shorewall-actions(5),
    shorewall-blacklist(5), shorewall-hosts(5), shorewall_interfaces(5), shorewall-ipsets(5),
    shorewall-maclist(5), shorewall-masq(5), shorewall-nat(5),
    shorewall-netmap(5), shorewall-params(5), shorewall-policy(5),
    shorewall-providers(5), shorewall-proxyarp(5), shorewall-route_rules(5),
    shorewall-routestopped(5), shorewall-rules(5), shorewall.conf(5), shorewall-secmarks(5),
    shorewall-tcdevices(5), shorewall-tcrules(5), shorewall-tos(5),
    shorewall-tunnels(5), shorewall-zones(5)</para>
  </refsect1>
</refentry>
