HP StorageWorks Enterprise File Services WAN Accelerator 3.0.4 deployment guide (AG421-96001, March 2007)

122 13 - TROUBLESHOOTING DEPLOYMENT PROBLEMS
If synchronization (SYN) packets that traverse from one side of the network are
optimized, but SYN packets that traverse from the opposite side of the network are
passed-through unoptimized, it is a symptom of network asymmetry.
The following figure shows an asymmetric server-side network in which a server
response can traverse a path (the bottom path) in which an HP EFS WAN Accelerator
is not installed.
Figure 13-1. Server-Side Asymmetric Network
The following sections describe several possible solutions to network asymmetry:
 “Solution: Use Connection Forwarding” on page 122
 “Solution: Use Virtual In-Path Deployment” on page 123
NOTE: Beginning with version 3.0, you can configure your HP EFS WAN Accelerators to
automatically detect and report asymmetric routes within your network. Whether asymmetric
routing is automatically detected by HP EFS WAN Accelerators or is detected in some other
way, use the solutions described in the following sections to work around it. For information on
configuring auto-detection of asymmetric routes, see the HP Enterprise File Services WAN
Accelerator Management Console User Guide.
Solution: Use
Connection
Forwarding
In order for a network connection to be optimized, packets traveling in both network
directions (from server to client and from client to server) must pass through the same
client-side and server-side HP EFS WAN Accelerator. In networks in which
asymmetric routing can occur because client requests or server responses can traverse
different paths, you can solve network asymmetry by:
1. Ensuring that there is an HP EFS WAN Accelerator installed on every possible
path a packet can traverse. In the example network shown in Figure 13-1 on page
122, you would install a second server-side HP EFS WAN Accelerator, covering
the bottom path.
2. Setting up connection forwarding to route packets that traversed one HP EFS
WAN Accelerator in one direction to traverse the same HP EFS WAN Accelerator
in the opposite direction. Connection forwarding can be configured on the
client-side or server-side of a network and is described in detail in Chapter 5,
“Connection Forwarding.” To set up connection forwarding, you use the
Management Console as described in “Configuring Connection Forwarding” on