Sample TCL Scripts

Important Note: If you are planning to run large simulations, make sure that you use the Heap scheduler ($ns use-scheduler Heap) instead of the default Calendar scheduler. It can save hours of simulation time for very large experiments.

Implementation Details

Figure 1: PackMimeHTTP Architecture. Each PackMimeHTTP object controls between 1-10 server and client clouds. Each cloud can represent multiple client or server Applications. Each Application represents either a single web server or a single web client.

Each web server or web client cloud is represented by a single ns node that can produce and consume multiple HTTP connections at a time (Figure 1). For each HTTP connection, PackMimeHTTP creates (or allocates from the inactive pool, as described below) server and client Applications and their associated TCP Agents. After setting up and starting each connection, PackMimeHTTP sets a timer to expire when the next new connection should begin. The time between new connections is governed by the connection rate parameter supplied by the user. New connections are started according to the connection arrival times without regard to the completion of previous requests, but a new request between the same client and server pair (as with HTTP 1.1) begins only after the previous request-response pair has been completed.

PackMimeHTTP handles the re-use of Applications and Agents that have completed their data transfer. There are 5 pools used to maintain Applications and Agents -- one pool for inactive TCP Agents and one pool each for active and inactive client and server Applications. The pools for active Applications ensure that all active Applications are destroyed when the simulation is finished. Active TCP Agents do not need to be placed in a pool beacuse each active Application contains a pointer to its associated TCP Agent. New objects are only created when there are no Agents or Applications available in the inactive pools.

PackMimeHTTP Client Application

• sample the number of requests for this connection from the number-of-requests distribution (if the number of requests is 1, this is an HTTP 1.0 connection)
• sample the inter-request times from the inter-request-time distribution, if there will be more than 1 request
• sample the HTTP request sizes from the request-size distribution
• send the first HTTP request to the server
• listen for the HTTP response
• when the entire HTTP response has been received, the client sets a timer to expire when the next request should be made
• when the timer expires, the next HTTP request is sent, and the above process is repeated until all requests have been completed

PackMimeHTTP Server Application

• listen for an HTTP request from the associated client
• when the entire request arrives, the server samples the server delay time from the server delay distribution
• set a timer to expire when the server delay has passed
• when the timer expires, the server samples the HTTP response sizes from the HTTP response size distribution
• this process is repeated until the requests are exhausted -- the server is told how many requests will be sent in the connection
• send a FIN to close the connection

PackMimeHTTP Random Variables

• RandomVariable/PackMimeHTTPFlowArrive rate, where rate is the specified PackMimeHTTP connection rate
• RandomVariable/PackMimeHTTPFileSize rate type, where type is 0 for HTTP requests and 1 for HTTP responses
• RandomVariable/PackMimeHTTPXmit rate type, where type is 0 for client-side transmission delays and 1 for server-side transmission delays

PackMimeHTTP TCL Commands

• set-client node, where node is an ns node
      associates the node with the PackMimeHTTP client cloud
• set-server node, where node is an ns node
      associates the node with the PackMimeHTTP server cloud
• start
      start the first connection
• stop
      stop generating new connections
• set-1.1
      use HTTP 1.1 distributions instead of HTTP 1.0
• set-debug int
      set the debugging level for PackMimeHTTP
• set-outfile filename
      use filename as the output file -- if this option is set, PackMimeHTTP will generate a file with the following fields (one line per HTTP request-response pair):
  1. time HTTP response completed
  2. HTTP request size (bytes)
  3. HTTP response size (bytes)
  4. HTTP response time (ms) -- time between client sending HTTP request and client receiving complete HTTP response
  5. source node and port identifier
  6. number of active connections at the time this HTTP request-response pair completed
• active-connections
      output the current number of active HTTP connections to standard error
• total-connections
      output the total number of completed HTTP connections to standard error
• set-warmup int
      set the warmup time - don't output PackMimeHTTP statistics before this time

  Connection Variables

• set-rate float
      set the average number of new connections started per second
• set-req_size RandomVariable
      set the HTTP request size distribution
• set-rsp_size RandomVariable
      set the HTTP response size distribution
• set-flow_arrive RandomVariable
      set the distribution of time between two consecutive connections
• set-server_delay RandomVariable
      set the web server delay for fetching pages

Choosing the TCP Type

The default TCP type for PackMimeHTTP is TCP Reno, but can be changed (though, it's not as straight-forward as it should be). Before you create the PackMimeHTTP instance in your TCL script, create a global hash variable named opts:

global opts

Then, set the tcp key of opts to be the desired TCP variant (Newreno for TCP NewReno and Sack for TCP SACK):

# sets TCP type for all PackMimeHTTP connections to TCP NewReno
set opts(tcp) "Newreno"

Use of DelayBox

Figure 2: Example Topology Using PackMimeHTTP and DelayBox. The cloud of web clients is a single ns node, and the cloud of web servers is a single ns node. Each of the DelayBox nodes is a single ns node.

• main page - removing ns-2.1b9 support, adding ns-2.28, copyright changed to modified BSD
• all source files - new copyright notice (modified BSD)
• test-suite-PackMime.tar.gz - put scripts in tcl/test directory
• packmime/packmime_HTTP.cc - change made so that request-response pairs will be the same between runs (with the same seed)

• Instructions for all versions: use 'patch -p0' instead of 'patch'
• test-packmime.tcl, test-packmime-min.tcl, test-packmime-delaybox.tcl: add $ns use-scheduler Heap

• updated test-packmime.tcl and test-packmime-delaybox.tcl
• added new test-packmime-min.tcl
• added sample output from above sample scripts

• packmime.tar.gz
  • fixed problem where tcl/packmime/packmime.tcl was left out of tarball

Copyright Statement

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Contacts: Michele Weigle (mcweigle@cs.unc.edu), Kevin Jeffay (jeffay@cs.unc.edu)

Home

|

Reference

Installation

Sample TCL Scripts

Implementation Details

Change Log

Copyright Statement