Global Loadbalancing with DNS

aiyappa · ‎07-24-2005

Hi

In the CSS Global load balancing I was going through the description of using the setup desribed, but I am confused about the following statements

"An application session is configured between two CSS switches in two different geographic locations. There is no requirement for a point-to-point link joining the sites; the only requirement is that the two sites can route to each other.

Using the CSS switches DNS capability, a higher level DNS server (in this example, the one authoritative for yourdomain.com) will be configured to use both CSS' circuit VLAN address as NS records for a sub-domain called www.yourdomain.com. Whichever CSS is referred to by the higher level DNS server will then resolve that a record request with the IP address of the DNS content rule on the CSS.

The primary site will be preferred through a combination of using an ACL on the secondary CSS, an application session between the two CSS switches, and configuring the above mentioned NS records on the higher-level DNS server"

Here are we only using the DNS feature of the CSS or another external DNS as well.

The information was obtained from the URL

http://www.cisco.com/en/US/products/hw/contnetw/ps789/products_configuration_example09186a00801dcd75.shtml

Any assistance would be extremely helpfull

Thank you

Regards

Aiyappa

Gilles Dufour · ‎07-24-2005

there is always an external DNS due to the protocol nature.

If you have a DNS server for your domain, say cisco.com, you will create an entry on this dns server to point www.cisco.com to the 2 CSS.

When a client does a domain name resolution for www.cisco.com they will first query the .com server, that will redirect the dns request to your server .cisco.com that will redirect the request to www.cisco.com which will be a CSS that can answer the DNS request with the VIP address.

If you don't have a dns server, for your .cisco.com network yet, you can contact the .com authorities and ask them to register one or to register the CSS directly [really not recommended as the CSS is very limited it what it can do with DNS].

So, to answer your question, no an external dns server is not required [you can test this function in a lab without dns server] but in a production environment you will need one.

Regards,

Gilles.