Disaster Recovery Routing

[davidclifford]

Some advice please?

I have a primary site with one IP subnet and a second (DR) site with a second IP subnet. Normally when customers connect they target the primary site and then have to build in a mechanism to failover to the secondary site if the primary is down. Is it possible to present a customer with a single IP address and within the router(s) located at their site automatically switch between sites dependant on the state of the line to either our primary or DR site.

[royalblues]

Can you describe your existing topology in a little more detail and the aplications the customer access?

Narayan

[pciaccio]

There are various ways to perform disaster recovery for your users. The solution you want would depend upon what applications your users are accessing. If Web pages or URL's then the best way would be to have redundant names for each application. ex. http://accountingsystem (resolved to 10.1.1.1) and use http://accountingsystemDR (resolved to 10.2.1.1). This way your users would redirect themselves to the backup subnet upon their need. You can also have the backup facility broadcast your DNS across the Internet upon the primary shutting down (Or in disaster mode). This will have all remote Internet access redirected to the backup facility. If specific IP's are used by your users then you would have no cloice but to have them keep two sets of IP's associated with their applications.. Some devices such as content switches assist in that a redundant site will have the paired Web content switch and keep a stateful session for all current access into your website. Upon disaster the redundant content switch will take over. IP's are the same. It is basically transparant to the remote user...Hope this helps....

[mchoo2005]

I presume you currently run static routing only? If you want automatic failover, you can implement dynamic routing between your data centres and the customer's site(s). The best protocol to use in this sort of scenario would be BGP.

An alternative is to use global server load balancing hardware, which will allow you to present 1 virtual IP address to the customer for a given application. The GSLB h/w can be configured to maintain a keepalive with both data centres, and automatically fails over your customers to the secondary site should your primary data centre is offline.

Typically, GSLB h/w is deployed in conjunction with server load balancing switches (a.k.a. Content switch, or application switch). In Cisco product portfolio, the GSLB h/w is the GSS series, while the server load balancing switch is the CSS series, which are part of Cisco's Content Networking suite of products.

Here's the link to the main website where you can find links to CSS and GSS series product info: http://www.cisco.com/en/US/products/ps5719/Products_Sub_Category_Home.html

HTH.