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Forum Discussion

buksy_12596's avatar
buksy_12596
Icon for Nimbostratus rankNimbostratus
May 16, 2007

Calculating Latency

Hi All     I am new to BIG-Ip and IRules, we have a F5 load balancer and I want to calculate the user latency of a HTTP request to a Virtual Server?     Is there any way i can use a IRUL...
application delivery
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iRules
Joe_Pruitt's avatar
Joe_Pruitt
May 16, 2007
Latency is something that really can only be measured on the client. Once the data gets to the BIG-IP until it leaves it, there is a lot of control, but the latency most often comes from the time it takes the client application (browser, etc) to reach the BIG-IP.

 

 

Off the top of my head, you could build a page with some javascript that adds the current time to the request when the request is made. Then build an iRule that just replays the request content back in a response along with some javascript to take that original time and subtract it from the current time that the response page is rendered. Not super accurate as the processing speed of the client machine could play on how fast the javascript is interpreted and executed.

 

 

Let me know if you were looking for more data than just the time to/from the BIG-IP. I've posted a tech tip on calculating the server application response time that may be useful

 

 

http://devcentral.f5.com/Default.aspx?tabid=63&articleType=ArticleView&articleId=66

 

Click here

 

 

 

Heck, sounds like a fun little tech tip. If you don't have time to tackle this, I'll see what I can come up with...

 

 

-Joe