I manage several F5 LTM devices which have a rapidly growing number of virtual servers configured (about 500 right now). I've noticed that when the device lists virtual servers it does so alphabetically, with no option to reorder them. This got me wondering, does the device check the entire list every time a connection is made? If so, how does the size of the list impact performance?
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Why would it 'check the list' for each connection? A virtual server is (usually) bound to a single IP and port. When a connection is made to that IP:port, it already knows what virtual server it's a part of. – Sep 14 '15 at 20:42
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We use different kinds of virtual servers. For example, one might match for an entire /24 subnet, while there are also several for specific IP's within that subnet. This means that for some connections there is more than one virtual server that matches. – D34DM347 Sep 15 '15 at 14:04
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Gotcha. I haven't seen any clear documentation about any associated overheard using this sort of configuration but [this document](https://support.f5.com/kb/en-us/solutions/public/14000/800/sol14800.html) describes the order of precedence. If you're concerned about performance, I'd contact F5 support and ask them. – Sep 15 '15 at 16:40
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Virtual server precedence is covered in this video, and I cover the flow tables for connections in this video. Hopefully this helps.
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Jason Rahm
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