Patent ID: 8521879

Claim:
An interior gateway protocol (IGP) intranet system, comprising: an Internet protocol (IP) core in the IGP intranet; a number of electronic communities external to the IP core in the IGP intranet, each having at least two layer 3 links directly to the IP core; a first layer 3 IGP network in the IGP intranet connected to the IP core, including: a first layer 4 load balancer that advertises a virtual network address and performs a health check on a first server connected to the first layer 4 load balancer; and a second layer 3 IGP network in the IGP intranet connected to the IP core, including: a second layer 4 load balancer that advertises the virtual network address; and a second server connected to the second layer 4 load balancer; and at least two layer 2 links between the first and the second servers, wherein the first layer 4 load balancer ceases to advertise the virtual network address when the health check indicates a particular criteria, and in response, the second layer 4 load balancer performs a controlled fallback including releasing the virtual network address back to the first layer 4 load balancer on at least one of a server-by-server and an application-by-application basis, and further wherein the first layer 4 load balancer does not cease advertising the virtual network address again for at least a given period of time.