Url Hashing For Server Load Balancing; Figure 15-3 Balancing Nontransparent Caches - Nortel Web OS Switch Software Application Manual

URL Hashing for Server Load Balancing

By default, hashing algorithms use the IP source address and/or IP destination address
(depending on the application area) to determine content location. The default hashing algo-
rithm for SLB is the IP source address. By enabling URL hashing, requests going to the same
page of an origin server are redirected to the same real server or cache server.
Virtual Server Load Balancing of Nontransparent Caches
You can deploy a cluster of non-transparent proxy caches and use the virtual server to load bal-
ance requests to the cache servers. The client's browser is configured to send Web requests to a
nontransparent cache (the IP address of the configured virtual server).
If hash is selected as the load-balancing algorithm, the switch hashes the source IP address to
select the server for SLB. Under this condition, the switch may not send Web requests for the
same origin server to the same proxy cache server. For example, requests made from a client to
"http://www.nortelnetworks.com/products" from different clients may get sent to different
caches.
Client's browser is configured
to send Web requests to the
origin server via the virtual server

Figure 15-3 Balancing Nontransparent Caches

Configuring URL Hashing
You can direct the same URL request to the same cache or proxy server by using a virtual
server IP address to load balance proxy requests. By configuring hash or minmisses as the
metric, the switch uses the number of bytes in the URI to calculate the hash key.
If the host field exists and the switch is configured to look into the Host: header, the switch
uses the Host: header field to calculate the hash key.
212777-A, February 2002
Virtual Server IP Address:
205.178.13.243
Chapter 15: Content Intelligent Switching
Web OS 10.0 Application Guide
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Non-Transparent
Cache Farm
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