Load Balancing

[Kim Kendall]

We are running Cisco IOS Server Load Balancing (SLB) on a 6509. This method of load balancing has a feature called Dynamic Feedback Protocol (DFP) that can be used to communicate to an "agent" running on the servers being load balanced. The agent gathers load information in the server and communicates via DFP to the 6509 with SLB. The SLB can then make a better decision on which server to send the next WEB request to.

What I am looking for is such an agent that runs on our WEB servers (L class running HPUX 11.00), and can determine how our web applications are loaded.

[harry d brown jr]

I sure hope this is an INTERNAL application and NOT an INTERNET application. I wouldn't open up a port between my web servers and network equipment unless someone could guarantee that it's more than Ivory Soap percentage secure!

Besides, wouldn't this "agent" come from Cisco, or are they using snmp?

live free or die
harry

[Christopher Caldwell]

http://www.platform.com/services/support/services/sitedfpwhitepapers.asp

Though the 6500 will balance based on TCP transaction time measurements:

From:
http://cio.cisco.com/warp/customer/cc/pd/si/casi/ca6000/tech/aslb_wp.htm

Advanced Server Algorithm
Several algorithm choices may be used for load balancing or determining which server will receive a new connection request. The algorithm of choice is the "least-connections" algorithm (leastconns); however, advanced server load balancing allows any one of the following load-balancing algorithms to be specified. They are detailed here, as well as any design configurations that may be affected.


Least connections???The number of sessions is based on the number of current TCP connections.

Network design impact???With multiple servers implemented with equal hardware and software configurations, it is practical to load the servers as evenly as possible, all the time. The least-connections option is aware when sessions disconnect, and eliminates the round-robin problem when many users log off one server, regardless of the server connection count.



Weighted percentage???Based upon a weighting metric specified during configuration, the sessions are distributed accordingly.

Network design impact???Weighted percentage is used if server hardware varies from server to server, resulting in vast differences between CPU performance between the two. It should be noted that even if this situation occurs, the end user does not notice any difference in performance because of the weighting.



Fastest???The weighted-predictor option allows you to assign a performance weight to each server. Weighted load balancing is similar to least connections, but servers with a higher weight value receive a larger percentage of connections at any one time.

Network design impact???This algorithm is not used in many data centers because typically server configuration is standardized and the performance is equal among all servers.



Round robin???The round-robin predictor option directs the network connection to the next server and treats all servers as equals, regardless of the number of connections or the response time.

[Kim Kendall]

Thanks Chris, but we already know about the these capabilities. We are looking for an agent running on the clients that will talk back to the Cisco.

[Sridhar Bhaskarla]

Hi,

My capabilities to evaluate Cisco products have been rusted and are very basic.

You have the default snmp agent running on the HP servers that can report the load utilization. Does your SLB has the capability to query the MIBs of snmp agent and then do the load balancing based on it??.

It will be free and fast.

-Sri

[Christopher Caldwell]

http://www.platform.com/services/support/services/sitedfpwhitepapers.asp
says their agent runs on HP-UX.