The ns Manual (formerly ns Notes and Documentation)1 - NM Lab at ...
The ns Manual (formerly ns Notes and Documentation)1 - NM Lab at ... The ns Manual (formerly ns Notes and Documentation)1 - NM Lab at ...
maxthresh_ The maximum threshold for the average queue size in packets.mean_pktsize_ A rough estimate of the average packet size in bytes. Used in updating the calculated average queuesize after an idle period.q_weight_ The queue weight, used in the exponential-weighted moving average for calculating the average queue size.wait_ Set to true to maintain an interval between dropped packets.linterm_ As the average queue size varies between "thresh_" and "maxthresh_", the packet dropping probability variesbetween 0 and "1/linterm".setbit_ Set to "true" to mark packets by setting the congestion indication bit in packet headers rather than drop packets.drop-tail_ Set to true to use drop-tail rather than randomdrop when the queue overflows or the average queue sizeexceeds "maxthresh_". For a further explanation of these variables, see [2].None of the state variables of the RED implementation are accessible.• CBQ objects: CBQ objects are a subclass of Queue objects that implement class-based queueing.$cbq insert Insert traffic class class into the link-sharing structure associated with link object cbq.$cbq bind [$id2]Cause packets containing flow id id1 (or those in the range id1 to id2 inclusive) to be associated with the traffic classcbqclass.$cbq algorithm Select the CBQ internal algorithm. may be set to one of: "ancestor-only", "top-level", or "formal".• CBQ/WRR objects: CBQ/WRR objects are a subclass of CBQ objects that implement weighted round-robin schedulingamong classes of the same priority level. In contrast, CBQ objects implement packet-by-packet round-robin schedulingamong classes of the same priority level. Configuration Parameters are:maxpkt_ The maximum size of a packet in bytes. This is used only by CBQ/WRR objects in computing maximumbandwidth allocations for the weighted round-robin scheduler.CBQCLASS OBJECTSCBQClass objects implement the traffic classes associated with CBQ objects.$cbqclass setparams Sets several of the configuration parameters for the CBQ traffic class (see below).$cbqclass parent specify the parent of this class in the link-sharing tree. The parent may be specified as “none” to indicate this class is a root.$cbqclass newallot Change the link allocation of this class to the specified amount (in range 0.0 to 1.0). Note that only the specified class isaffected.$cbqclass install-queue Install a Queue object into the compound CBQ or CBQ/WRR link structure. When a CBQ object is initially created, itincludes no internal queue (only a packet classifier and scheduler).Configuration Parameters are:okborrow_ is a boolean indicating the class is permitted to borrow bandwidth from its parent.allot_ is the maximum fraction of link bandwidth allocated to the class expressed as a real number between 0.0 and 1.0.75
maxidle_ is the maximum amount of time a class may be required to have its packets queued before they are permitted to beforwardedpriority_ is the class’ priority level with respect to other classes. This value may range from 0 to 10, and more than one classmay exist at the same priority. Priority 0 is the highest priority.level_ is the level of this class in the link-sharing tree. Leaf nodes in the tree are considered to be at level 1; their parents areat level 2, etc.extradelay_ increase the delay experienced by a delayed class by the specified timeQUEUE-MONITOR OBJECTSQueueMonitor Objects are used to monitor a set of packet and byte arrival, departure and drop counters. It also includessupport for aggregate statistics such as average queue size, etc.$queuemonitorreset all the cumulative counters described below (arrivals, departures, and drops) to zero. Also, reset the integrators anddelay sampler, if defined.$queuemonitor set-delay-samples Set up the Samples object delaySamp_ to record statistics about queue delays. delaySamp_ is a handle to a Samples objecti.e the Samples object should have already been created.$queuemonitor get-bytes-integratorReturns an Integrator object that can be used to find the integral of the queue size in bytes.$queuemonitor get-pkts-integratorReturns an Integrator object that can be used to find the integral of the queue size in packets.$queuemonitor get-delay-samplesReturns a Samples object delaySamp_ to record statistics about queue delays.There are no configuration parameters specific to this object.State Variables are:size_ Instantaneous queue size in bytes.pkts_ Instantaneous queue size in packets.parrivals_ Running total of packets that have arrived.barrivals_ Running total of bytes contained in packets that have arrived.pdepartures_ Running total of packets that have departed (not dropped).bdepartures_ Running total of bytes contained in packets that have departed (not dropped).pdrops_ Total number of packets dropped.bdrops_ Total number of bytes dropped.bytesInt_ Integrator object that computes the integral of the queue size in bytes. The sum_ variable of this object has therunning sum (integral) of the queue size in bytes.pktsInt_ Integrator object that computes the integral of the queue size in packets. The sum_ variable of this object has therunning sum (integral) of the queue size in packets.76
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- Page 45 and 46: $ns_ dumpqCommand for dumping event
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maxidle_ is the maximum amount of time a class may be required to have its packets queued before they are permitted to beforwardedpriority_ is the class’ priority level with respect to other classes. This value may range from 0 to 10, <strong>and</strong> more than one classmay exist <strong>at</strong> the same priority. Priority 0 is the highest priority.level_ is the level of this class in the link-sharing tree. Leaf nodes in the tree are co<strong>ns</strong>idered to be <strong>at</strong> level 1; their parents are<strong>at</strong> level 2, etc.extradelay_ increase the delay experienced by a delayed class by the specified timeQUEUE-MONITOR OBJECTSQueueMonitor Objects are used to monitor a set of packet <strong>and</strong> byte arrival, departure <strong>and</strong> drop counters. It also includessupport for aggreg<strong>at</strong>e st<strong>at</strong>istics such as average queue size, etc.$queuemonitorreset all the cumul<strong>at</strong>ive counters described below (arrivals, departures, <strong>and</strong> drops) to zero. Also, reset the integr<strong>at</strong>ors <strong>and</strong>delay sampler, if defined.$queuemonitor set-delay-samples Set up the Samples object delaySamp_ to record st<strong>at</strong>istics about queue delays. delaySamp_ is a h<strong>and</strong>le to a Samples objecti.e the Samples object should have already been cre<strong>at</strong>ed.$queuemonitor get-bytes-integr<strong>at</strong>orRetur<strong>ns</strong> an Integr<strong>at</strong>or object th<strong>at</strong> can be used to find the integral of the queue size in bytes.$queuemonitor get-pkts-integr<strong>at</strong>orRetur<strong>ns</strong> an Integr<strong>at</strong>or object th<strong>at</strong> can be used to find the integral of the queue size in packets.$queuemonitor get-delay-samplesRetur<strong>ns</strong> a Samples object delaySamp_ to record st<strong>at</strong>istics about queue delays.<strong>The</strong>re are no configur<strong>at</strong>ion parameters specific to this object.St<strong>at</strong>e Variables are:size_ I<strong>ns</strong>tantaneous queue size in bytes.pkts_ I<strong>ns</strong>tantaneous queue size in packets.parrivals_ Running total of packets th<strong>at</strong> have arrived.barrivals_ Running total of bytes contained in packets th<strong>at</strong> have arrived.pdepartures_ Running total of packets th<strong>at</strong> have departed (not dropped).bdepartures_ Running total of bytes contained in packets th<strong>at</strong> have departed (not dropped).pdrops_ Total number of packets dropped.bdrops_ Total number of bytes dropped.bytesInt_ Integr<strong>at</strong>or object th<strong>at</strong> computes the integral of the queue size in bytes. <strong>The</strong> sum_ variable of this object has therunning sum (integral) of the queue size in bytes.pktsInt_ Integr<strong>at</strong>or object th<strong>at</strong> computes the integral of the queue size in packets. <strong>The</strong> sum_ variable of this object has therunning sum (integral) of the queue size in packets.76
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