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       tcclasses - Shorewall file to define HTB classes




       A note on the rate/bandwidth definitions used in this file:

       ·   don't use a space between the integer value and the unit: 30kbit is
           valid while 30 kbit is NOT.

       ·   you can use one of the following units:

               Kilobytes per second.

               Megabytes per second.

               Kilobits per second.

               Megabits per second.

           bps or number
               Bytes per second.

       ·   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:

               causes the bandwidth to be calculated as 1/3 of the full
               outgoing speed that is defined.

               will set this bandwidth to 9/10 of the full bandwidth

           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.

           DO NOT add a unit to the rate if it is calculated !

       The columns in the file are as follows.

       INTERFACE - interface[[:parent]:class]
           Name of interface. Each interface may be listed only once in this
           file. You may NOT specify the name of an alias (e.g., eth0:0) here;

           You may specify the interface number rather than the interface
           name. If the classify option is given for the interface in
           shorewall-tcdevices[1](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 class 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.

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

           Please note that you can only use interface names in here that have
           a bandwidth defined in the shorewall-tcdevices[1](5) file.

           Normally, all classes defined here are sub-classes of a root class
           that is implicitly defined from the entry in
           shorewall-tcdevices[1](5). You can establish a class hierarchy by
           specifying a parent class -- the number of a class that you have
           previously defined. The sub-class may borrow unused bandwidth from
           its parent.

       MARK - {-|value}
           The mark value which is an integer in the range 1-255. You set mark
           values in the shorewall-tcrules[2](5) file, marking the traffic you
           want to fit in the classes defined in here. Must be specified as
           '-' if the classify option is given for the interface in

           You can use the same marks for different interfaces.

       RATE - rate[:dmax[:umax]]
           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.

           When using the HFSC queuing discipline, leaf classes may specify
           dmax, 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).

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

       CEIL - rate
           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.

           You can use the value full 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.

       PRIORITY - priority
           The priority 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.

           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).

           Classes may be set to the same priority, in which case they will be
           serviced as equals.

       OPTIONS (Optional) - [option[,option]...]
           A comma-separated list of options including the following:

               This is the default class for that interface where all traffic
               should go, that is not classified otherwise.

                   You must define default for exactly one class per

           tos=0xvalue[/0xmask] (mask defaults to 0xff)
               This lets you define a classifier for the given value/mask
               combination of the IP packet's TOS/Precedence/DiffSrv octet
               (aka the TOS byte).

               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.

                           tos-minimize-delay       0x10/0x10
                           tos-maximize-throughput  0x08/0x08
                           tos-maximize-reliability 0x04/0x04
                           tos-minimize-cost        0x02/0x02
                           tos-normal-service       0x00/0x1e

                   Each of these options is only valid for ONE class per

               If defined, causes a tc filter to be created that puts all tcp
               ack packets on that interface that have a size of <=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.

                   This option is only valid for ONE class per interface.

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

               When 'occurs' is used:

               ·   The associated device may not have the 'classify' option.

               ·   The class may not be the default class.

               ·   The class may not have any 'tos=' options (including

               ·   The class should not specify a MARK value. If one is
                   specified, it will be ignored with a warning message.

               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 number. For additional
               information, see tcrules[2] (5).

               Shorewall attaches an SFQ queuing discipline to each leaf HTB
               class. SFQ ensures that each flow 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 flow 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:
                   Shaping internet-bound traffic:
                   Shaping traffic bound for your local net:
               These will cause a 'flow' to consists of the traffic to/from
               each internal system.

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

               To see a list of the possible flow keys, run this command: tc
               filter add flow help 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 before NAT as the key.

               When specified for a leaf class, the pfifo queing discipline is
               applied to the class rather than the sfq queuing discipline.

               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 number must be > 2 and <=128. If not
               specified, the value 127 is assumed.


       Example 1:
           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.

           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).

           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.

           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.

           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.

                       #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




       shorewall(8), shorewall-accounting(5), shorewall-actions(5),
       shorewall-blacklist(5), shorewall-hosts(5), shorewall-interfaces(5),
       shorewall-ipsec(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-tcdevices(5),
       shorewall-tcrules(5), shorewall-tos(5), shorewall-tunnels(5),


        1. shorewall-tcdevices

        2. shorewall-tcrules

[FIXME: source]                   06/17/2010