Re: [load balancing] Outbound HTTP throttling

From: Kelly Vista <kvista7 [izzat]>
Date: Fri May 08 2009 - 16:16:25 EDT

Thanks very much for the feedback.

This is in fact what we do right now. Problem is that it's been hard to
configure. Also, I am not sure how much confidence I have in the need to
balance requests to FQDNs. I should have mentioned that I need throttling
to something like "", not to "". I can't ensure the
remote IP will be static.

On Fri, May 8, 2009:

> The latest version of netscaler has a rate limiting feature but I think
> it can only be applied to load balanced traffic for which the netscaler
> is a reverse proxy. Maybe you can use it as a "reverse load balancer"
> and set up VIPs to front-end external server and your API code hits
> those VIPs.

> *From:* [] *On Behalf
>> Of *Kelly Vista
>> *Sent:* Friday, May 08, 2009 11:30 AM
>> *To:*
>> *Subject:* [load balancing] Outbound HTTP throttling
>> Hi -
>> At our company, we make use of a lot of "web APIs" that exist. For
>> example, Google has a search API, Netflix has an API, etc. Using these
>> APIs, we can create a lot of "mashups" or richly integrated data sets.
>> However, we would like to be a "good Internet citizen" and obey the rate
>> limiting requirements of the sites we hit. For example, many companies have
>> rate limiting policies like "no more than 5 requests per second".
>> Unfortunately, since we have many machines that - for several different
>> applications - hit these sites, we need to make sure that our *aggregate*
>> use is no more than 5 (or whatever) requests per second.
>> I'm writing to this list because I believe there may be load balancers
>> with L4 or L7 capabilities that allow us to do this and I was looking for
>> suggestions. We are in the process of testing out Citrix NetScaler for this
>> and, although it seems somewhat capable, it's been very tricky to configure.
>> To re-iterate the complexity of our particular problem, it has to do with
>> rate limiting outbound traffic based on number of connections/requests per
>> second.
>> If anyone has any insight into solutions that do this (h/w or s/w), I
>> would appreciate it.
>> For the record, I know there are software solutions like like Apache
>> mod_throttle and mod_cband, Linux iptables, Squid, Vista Server QoS, etc.
>> I'm open to any of these provided it's straightfoward to manage. I would
>> prefer the reliability of solid state, but my first priority is any kind of
>> solution, reliability can be an "optimization".
>> Thanks for any and all help,
>> --kv
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Received on Fri May 8 16:30:01 2009

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