NetScaler realization of control of main and standby service

Many people often ask how to achieve 2 or more servers of the same business of the main standby function, that is, the use of the same VIP, the backend corresponding to 2 or more real servers, but under normal circumstances only 1 or some of the primary server, only if the main server after the problem of the remaining server to take over the identity of the server.
Technically, this requirement is unwise, but as long as it is justified, you cannot completely influence the customer's idea. Since there is a need, as a powerful netscaler naturally have a solution, but this demand is against the load balancer design, so we do not quite understand how to configure. Then write a blog to avoid answering similar questions frequently.

In NetScaler to achieve the above requirements have three kinds of practices (seemingly a convincing built-in related algorithms, really served), the specific use of what method please according to the specific business situation to choose
1, through the backup vserver to achieve
Logical diagram

Configuration:
Create a new two vserver, two vserver add their own service

Two vserver corresponding service (this replaces two Web servers with a different web port)

Set standby vs on Primary vs

Access primary under normal circumstances

Access backup under normal conditions

Disable 80-port analog primary server failure

At this point the primary becomes down, but the actual effect is still up

User access to 192.168.0.57 (primary IP) is still fine, and hostname has not changed.

2, through the listen policy to achieve
Logical diagram

Configuration
Create a new two vs with a total of 80 ports

Primary binding a 80-port Service,primary2 binding 81-port service to simulate two servers
Slightly
Configuring Listen policy for Primary2

Normal access, hit primary vs

Disable 80-port service, simulate primary server failure, VS becomes the following status

Visit the business again, hit Primary2 vs

Business Normal
3, through Monitor to achieve
Logical diagram

Configuration

TICK reverse

Status of the service under normal conditions, backup is down

Create a new vSERVER, bind two service

Disable 80-port analog failure, service status

Access to Business normal

By deeply understanding the various parameters of NetScaler, we can provide many ways to solve the problem.

NetScaler realization of control of main and standby service