ACE Design/Performance Question

[jbartoldus]

I have been asked to consider moving the load balancing functionality that another product is providing (IBM's Datapower) to our Cisco ACE implementation.

The Datapower device listens on port 80 and makes load balancing decisions based on the URI string (same HTTP host) and redirects the request (port redirection) to a set of load balanced real servers listening on various TCP ports (a different TCP port per unique URI string). There are over 250 different URI strings that each result in a different load balance decision (over 250 backend TCP ports).

Two questions.....

1. Functionally, can the ACE do this...

• x number of rservers
  
• 250 different serverfarms
  
• 1 L4 class-map
  
• 250 different L7 class-maps (1 per unique URI string)
  
• 1 loadbalanced policy-map with 250 class statements <--- Can the ACE support this many class statements in one loadbalanced policy-map?
  

2. Are there performance implications?

• ACE 20 modules in 6500s running A2(3) code with all that regex parsing
  
• Approx 1 million hits a day
  

Thanks for any help/advice you can give.

[litrenta · Accepted solution]

you can do this with ACE, however instead of class maps you would use inline match statements. Since you are using unique uri's you woudl want to avoid wildcarding to preserve regex memory. You can have up to 1024 instances of the same type of with a layer 4 policy-map. example of inline match policy:

policy-map type loadbalance first-match inline_example

  match one http url /test1/path1

    serverfarm FARM1

  match two http url /test2/path2

    serverfarm FARM2

see:

http://www.cisco.com/en/US/docs/interfaces_modules/services_modules/ace/vA2_3_0/configuration/slb/guide/classlb.html#wp1021638

Performance implications are simply that everything is treated as L7 so concurrent session (per blade not context) would be 512K rather than L4 4M, CPS 116K vs 256K L4,  This is assuming you are not doing SSL.