Installation guide

7-3
Device Manager Guide, Cisco ACE 4700 Series Application Control Engine Appliance
OL-26645-02
Chapter 7 Configuring Stickiness
Stickiness Overview
• Layer 4 Payload Stickiness, page 7-4
• RADIUS Stickiness, page 7-5
• RTSP Header Stickiness, page 7-5
• SIP Header Stickiness, page 7-5
• SSL Stickiness, page 7-5
HTTP Content Stickiness
HTTP content stickiness allows you to stick a client to a server based on the content of an HTTP packet.
You can specify a beginning pattern and ending pattern, the number of bytes to parse, and an offset that
specifies how many bytes to ignore from the beginning of the data.
Related Topics
• Configuring Sticky Groups, page 7-11
• Sticky Types, page 7-2
• Sticky Groups, page 7-6
• Sticky Table, page 7-11
HTTP Cookie Stickiness
Client cookies uniquely identify clients to the ACE and the servers providing content. A cookie is a small
data structure within the HTTP header that is 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 connection state or persistence between the client and the server.
When the ACE examines a request for content and determines through policy matching that the content
is sticky, it examines any cookie or URL present in the content request. The ACE uses the information
in the cookie or URL to direct the content request to the appropriate server.
The ACE supports the following types of cookie stickiness:
• Dynamic cookie learning
You can configure the ACE to look for a specific cookie name and automatically learn its value
either from the client request HTTP header or from the server Set-Cookie message in the server
response. Dynamic cookie learning is useful when dealing with applications that store more than
just the session ID or user ID within the same cookie. Only very specific bytes of the cookie value
are relevant to stickiness.
By default, the ACE learns the entire cookie value. You can optionally specify an offset and length
to instruct the ACE to learn only a portion of the cookie value.
Alternatively, you can specify a secondary cookie value that appears in the URL string in the HTTP
request. This option instructs the ACE to search for (and eventually learn or stick to) the cookie
information as part of the URL. URL learning is useful with applications that insert cookie
information as part of the HTTP URL. In some cases, you can use this feature to work around clients
that reject cookies.
• Cookie insert
The ACE inserts the cookie on behalf of the server upon the return request, so that the ACE can
perform cookie stickiness even when the servers are not configured to set cookies. The cookie
contains information that the ACE uses to ensure persistence to a specific real server.