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I need to balance traffic to several HTTP listeners. They are in two groups for two different purposes. To illustrate...
        |           |        |        |        |
     +--+--+      +-+-+    +-+-+    +-+-+    +-+-+ 
     | LB1 |      | A |    | B |    | C |    | D |
     +-----+      +---+    +---+    +---+    +---+
     balance                 4 web servers

I want LB1 to spray URL pattern* to either web server A or B, and LB1 to spray URL pattern* to either web server C or D.

I have used pen to load balance successfully, but it does not offer this URL pattern matching feature.

Is there something as simple and robust as pen out there that can also do URL pattern matching?

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up vote 3 down vote accepted

Some Popular Load Balancers / Reverse Proxies that support this are:

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I'd add perlbal to Kyle's excelent list. – Marco Ramos Jun 22 '10 at 18:07
Chose pound for no particular reason. – dacracot Jun 22 '10 at 18:57

I am sure most users here would balk, but Microsoft has recently released their ARR Load Balancing product which along with IIS 7 and rewrite rules can do all you suggest and more as well as having failover between AAR nodes, etc. You can check it out here. It was highlighted at the tech ed conference this month in New Orleans and is already being used by at least one Web hosting company (the speaker was from the company in question , although the name escapes me). Overall it seems like a very well designed product, if I didn't already have hardware load balancers in place I would definitely consider it.

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balk ;-) I would be curious to hear peoples experiences with it... – Kyle Brandt Jun 22 '10 at 18:24
I kind of thought the same thing, but at the conference there were several people currently using it and even using it in conjunction with hardware load balancers and the consensus among them was that it was that it was a good product, easy to use and configure and light on resources. The session can be viewed at The session host works for and states in the session that they are using it for commercial hosting for their customers. – Charles Jun 22 '10 at 19:43
The only thing that can make a load balancer suitable to users and customers is in-field experience. There's nothing better than the contact with the people who will use such products to get reports of what feature to add even if they look dirty. Also, whatever efforts you make to try to get the most reliable product, you'll always have nasty bugs caused by combinations of corner cases of several features. If their product comes from nowhere and was secretly developed in their ceilar, I doubt it gets the required experience to be reliable enough yet ! – Willy Tarreau Jun 22 '10 at 20:18

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