Changes between Version 17 and Version 18 of Internal/RunningDemos


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Timestamp:
Dec 23, 2005, 6:17:21 PM (19 years ago)
Author:
kishore
Comment:

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  • Internal/RunningDemos

    v17 v18  
    1111The objective of this demo is to show the failure of current implementations of IEEE 802.11 infrastructure networks in supporting a large number (O(10)) of clients. The cumulative throughput at the access point (AP) is the measured and it is shown that beyond a certain number of clients, there is a sharp drop rather than graceful degradation. It is hypothesized that the 802.11 bit-rate adaptation algorithm is the primary culprit for this behavior - the algorithm does not differentiate between collision-based packet loss and packet loss due to poor channel conditions. It incorrectly infers collision-based loss as an indication to drop the bit-rate, resulting in the sharp drop in cumulative throughput.
    1212
     13The demo itself consists of one receiver and 25 senders -- the start times of the senders are staggered (3-4 senders join the experiment in 10 second intervals). Traffic generated is UDP-CBR (constant bit-rate) at 1.5Mbps emulating high-quality video streaming from the clients to the AP.
     14
    1315=== Steps to Execute Demo ===
    1416
    15 1. '''Image name''' -- baseline.ndz node image file must be used. Resides on repository2:/export/orbit/image. 
     171. '''Image name''' -- conf-room-demo.ndz node image file must be used. Resides on repository2:/export/orbit/image. 
    1618   a. Log onto console.sb9.orbit-lab.org using ssh (see HowToGetStarted).
    1719   b. Turn off all nodes using the following command:
     
    2123   c. Execute the following command on console.sb9.
    2224{{{
    23 imageNodes atheros baseline.ndz
     25imageNodes atheros conf-room-demo.ndz
    2426}}}
    2527
     
    3032
    31333. '''Display machine'''
    32 On the display machine, point your Internet Explorer or Mozilla Firefox browser to http://sb9.orbit-lab.org
     34On the display machine, point your Internet Explorer or Mozilla Firefox browser to http://sb9.orbit-lab.org. What you expect to see is a page with three frames - one showing the topology of the smaller grid, one showing a control interface to change the packet size and offered load and the third with a link to plot the cumulative throughput at the access point (AP).
     35
     36The frame showing the topology should initially display 64 yellow boxes representing the nodes on the grid. Once the nodes in the experiment turn ON, the corresponding yellow boxes will turn green. Once the applications start on the nodes, the senders will turn blue and the receiver will turn red.
     37 
     38Click the link for the cumulative throughput in the third frame -- the expected behavior for the curve is that initially, the throughput will rise as senders are added but beyond a certain number of senders, throughput will fall drastically.
    3339
    3440== Streaming video demo ==