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Web OS 10.0 Application Guide
426
Chapter 16: Persistence
212777-A, February 2002
Cookie Properties
Cookies are configured on the Web switch by defining the following properties:
n Cookie names of up to 20 bytes
n The offset of the cookie value within the cookie string
For security, the real cookie value can be embedded somewhere within a longer string.
The offset directs the Web switch to the starting point of the real cookie value within the
longer cookie string.
n Length of the cookie value
This defines the number of bytes to extract for the cookie value within a longer cookie
string.
n Whether to find the cookie value in the HTTP header (the default) or the URL
n Cookie values of up to 64 bytes for hashing
Hashing on cookie values is used only with the passive cookie mode (“Passive Cookie
Mode” on page 428), using a temporary cookie. The switch mathematically calculates the
cookie value using a hash algorithm to determine which real server should receive the
request.
n An asterisk (*) in cookie names for wildcards
For example, Cookie name = ASPsession*
Client Browsers that Do Not Accept Cookies
Under normal conditions, most browsers are configured to accept cookies. However, if a client
browser is not configured to accept cookies, you must use hash as the load-balancing metric
to maintain session persistence.
With cookie-based persistence enabled, session persistence for browsers that do not accept
cookies will be based on the source IP address. However, individual client requests coming
from a proxy firewall will appear to be coming from the same source IP address. Therefore, the
requests will be directed to a single server, resulting in traffic being concentrated on a single
real server instead of load balanced across the available real servers.