HP StorageWorks Enterprise File Services WAN Accelerator Deployment Guide (November 2005)

HP EFS WAN ACCELERATOR DEPLOYMENT GUIDE 45

5 - CONFIGURING CONNECTION

ORWARDING

If there are more than two possible paths, additional HP EFS WAN

Accelerators must be installed on each path and configured as neighbors.

Neighbors receive information in parallel (the delay introduced at connection

set up is equal to the time it takes to get an acknowledgement from the furthest

neighbor).

If one of the neighbor HP EFS WAN Accelerators reaches its optimization

capacity limit, that HP EFS WAN Accelerator will not accept new connections,

but it redirects packets to other neighbors for optimization.

One-to-One Failover Deployment

To ensure optimization in the event of a failure, a backup HP EFS WAN

Accelerator can be added to each neighbor HP EFS WAN Accelerator in a one-

to-one failover configuration.

In Figure 5-2 there are two HP EFS WAN Accelerators on each path that are

configured in a one-to-one failover mode. Each HP EFS WAN Accelerator

must be a neighbor of the master and backup HP EFS WAN Accelerators on

the other paths.

Figure 5-2. One-to-One Failover Deployment

HP EFS WAN Accelerator-2 and HP EFS WAN Accelerator-2B are configured

as neighbors of HP EFS WAN Accelerator-1 which exchanges connection

information with both of them so that if either HP EFS WAN Accelerator-2 or

HP EFS WAN Accelerator-2B fails, the other redirects packets to HP EFS WAN

Accelerator-1.

In Figure 5-2, packets from the server are redirected by HP EFS WAN

Accelerator-2B unless it fails in which case they are redirected by HP EFS

WAN Accelerator-2.

As long as one of the two failover HP EFS WAN Accelerators on each path is

up, connections are intercepted. If the two HP EFS WAN Accelerators on the

same path fail, connections stop being intercepted and optimized.