Bit Rate Throttling

Is there a way to enable Bit Rate Throttling module on my DASP Web site?

Or maybe there is another solution to my problem?

I have a portion of my site that is accessed exclusively by wireless mobile devices and often times the responses to HTTP requests for certain files (.cab and .jpg) crawl down to almost a halt.

Here is what I was able to figure out is happening by using Network Monitor to monitor TCP traffic (bear with me, I hope I can exlpain it clearly):

1. After receiving a HTTP request for a .cab or .jpg file, mu DASP Web site starts sending a response at full bandwidth

2. Mobile device starts acknowledging each received TCP packets.

3. DASP web site keeps pumping at full bandwidth until it hits the TCP Window Size (acknowlegemnts are not keeping up with the TCP stream coming from the server), after which the bandwidth is pretty much determined by the speed at which acknowlegements are coming back from the mobile device, a new TCP packet for every acknowlegment received.

4. Sometimes, and often enough that it is unacceptable, it seems that the response at full bandwidth overwhelms the wireless provider's routers (I guess somewhere inside the ATT GSM network in my case) and it either drops the packets going to mobile device, drops the acknowledment packets coming back from the device, or possibly both. In any case, my DASP Web site (Win 2008) recognizes that acknowledgments are not comming back and it stops sending any packets for 5 seconds or so, even if some acknowledments come back in the mean time.

5. After the 5 seconds period of inactivity my DASP web site sends exactly the same number of new TCP packets as the number of acknowlegment packets that came back in the meantime.

6. In case when returning acknowledgments are delayed again , my WEB DASP recycles itself back to not sending any more TCP packets, but this time for more than 15 seconds. Again, once it goes into silent mode, even if some acknowlegments come back in the meantime, it want send anymore TCP packets until the 15 second time out expires

7. In most cases, now that acknowledgments started being delayed, new acknowledgments will again be delayed which causes my DASP Web site to go into yet another cycle of silence, this time for 60 seconds or so of sending no further TCP packets. These silent cycles will eventually actually make initial HTTP request expire on the mobile device.

So, I either have to throttle the bandwidth so my web site is not sending more that what wireless (ATT, Verizon, Sprint) can handle, or to somehow configure TCP/IP stack on my DASP Web site not to go into those silent modes (I guess TCP/IP Congestion Detection and Avoidance is messing me up)


Thanks in advance, I hope someone will be able to provide useful suggestions.

 

There is an IIS7 module that has been kicking around for a while - http://weblogs.asp.net/scottgu/archive/2008/03/18/iis-7-0-bit-rate-throttling-module-released.aspx. I read that it's intended for use in video streaming scenarios and it will need installing on the server so I'm not sure how far you're going to get with it.