Chapter 4 Configuring Sticky Cookies
Advanced Load-Balancing Method Using Cookies
4-2
Cisco Content Services Switch Getting Started Guide
OL-6037-01
Stickiness is the association between a client and a server that the CSS maintains
during a session. Stickiness enables transactions over the Web because the client
must remain on the same server for the entire session. Depending on the content
rule, the CSS “sticks” a client to an appropriate server after the CSS has
determined which load-balancing method to use.
If the CSS determines that a client is already stuck to a particular service, then the
CSS places the client request on that service, regardless of the load balancing
criteria specified by the matched content rule. If the CSS determines that the client
is not stuck to a particular service, it applies normal load balancing to the content
request.
Client
cookies
uniquely identify clients to the services providing content. A
cookie is a small data structure used by a server to deliver data to a Web client and
request that the client store the information. In certain applications, the client
returns the information to the server to maintain the state between the client and
the server.
When the CSS examines a request for content and determines through content rule
matching that the content is sticky, it examines any cookie or URL present in the
content request. The CSS uses this information to place the content request on the
appropriate server.
Advanced Load-Balancing Method Using Cookies
A content rule is “sticky” when additional sessions from the same user or client
are sent to the same service as the first connection, overriding normal load
balancing. By default, the advanced balancing method is disabled.
Use the
advanced-balance
command to specify an advanced load-balancing
method for a content rule that includes stickiness. The
advanced-balance
command options (
cookies
,
cookieurl
, and
url
) use strings for sticking clients to
servers. These options are beneficial when the sticky table limit is too small for
your application requirements because the string methods do not use the sticky
table.
