Service load

David Coupez · ‎10-03-2008

Hello,

I wonder how CSS calculate the server load. There is a way to limit the throughput of a server but it has to be expressed by a number between 0 and 254. Not so clear what to choose!

Thank you for your explanations.

David

sachinga.hcl · ‎10-04-2008

Hi David,

When a request for content is made, the CSS:

1. Uses the owner content rule to translate the owner Virtual IP address (VIP) or domain name using Network Address Translation (NAT) to the corresponding service IP address and port.

2. Checks for available services that match the content request.

3. Uses content rules to choose which service can best process the request for content.

4. Applies all content rules to service the request for content (for example, load balancing method, redirects, failover, stickiness).

Service Load Overview

Server load is a mechanism to express the current load experienced by a server. The CSS calculates load by using the variances in normalized response times from client to server to determine a server's load number. A server with a heavier processing load would be biased toward a more significant, larger, load number.

To configure global load parameters for the eligibility and ineligibility of CSS services, use the load report, load teardown timer, and load ageout timer commands (discussed later in this section).

You can adjust load calculations by changing the load step size, which is the difference in milliseconds between load numbers. The CSS can determine the load step dynamically, or you can configure the initial load step using the global load step command.

The load on a service has a range of 2 to 255, with an eligible load of 2 to 254. An eligible service is an active service that can receive flows. A service with a load of 255 is offline.

A service becomes ineligible to receive flows when its load number exceeds the configured load threshold. The CSS uses the configured ageout timer value to return the service to the eligible state.

For the CSS to consider the server loads as different, response times of the servers must differ by the configured load step or greater. If the response times differ by less than the configured load step, the CSS considers the servers to have the same load.

use the below mentioned url to get the details about load balancing method example:

http://www.cisco.com/en/US/docs/app_ntwk_services/data_center_app_services/css11000series/v5.00/configuration/basic/guide/Services.html#wp1015600

kind regards,

Sachin Garg

Senior Specialist Security

HCL Comnet Ltd.

http://www.hclcomnet.co.in

A-10, Sector 3, Noida- 201301

INDIA

Mob: +91-9911757733

Email: sachinga@hcl.in