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C H A P T E R 4Intel® NetStructure™ 7190 Multi-Site Traffic Director User Guide
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create-authority ns5.mstd-ex.com ip 10.1.1.5
config dns zones
create div2.mstd-ex.com
div2.mstd-ex.com
create-authority ns1.mstd-ex.com ip 10.1.1.1
create-authority ns2.mstd-ex.com ip 10.1.1.2
create-authority ns3.mstd-ex.com ip 10.1.1.3
create-authority ns4.mstd-ex.com ip 10.1.1.4
create-authority ns5.mstd-ex.com ip 10.1.1.5
Step 4. Add hosts for the first zone and map their services.
A limitation of DNS is there is no built-in way of conveying exactly
what service the client actually needs. A request for www.mstd-
ex.com could easily be for either HTTP or HTTPS service. A major
feature of the 7190 is that it is service aware. It knows about the actual
availability of services and can direct clients to the best site for that
service. The problem lies in that the 7190 has no idea what service the
client wants unless a one-to-one mapping of service types to host
names is made in the configuration. In this example scenario it would
be easy to lump both the HTTP and HTTPS services together in the
configuration for the hostname www.div1.mstd-ex.com. But a
problem could occur if one of the services ever failed at a site; the
others are still available. Even though one service has failed, the other
is still available and all that is returned to the client is the IP address.
The subsequent attempts by the client to use the referred address fails
because it is asking for a service that is unavailable at that site. The
solution requires a little more work in the host Web pages, but allows
full advantage to be taken of the service awareness of the 7190. If
unique hostnames are used for each service type, this problem never
occurs. Note that if the load balancers are either Intel®
NetStructure
TM
7180s or are fronted by Intel® NetStructure
TM
7110s,
there is less of an issue with combining HTTP services with HTTPS
services. Most of the traffic ever reaching a server would be HTTP.
In this scenario the services available on a single Web site have been
divided into three different hostnames: www (HTTP), wwwsecure
(HTTPS), and ftp (FTP). Another advantage of dividing the service
types like this is that each hostname can be configured to use a
different balancing method. Typically FTP traffic is fewer
connections, but longer connection times. This is ideal for balancing
by Least Connections. Secure traffic (HTTPS) or layer 7 load