HP AA979A - StorageWorks SAN Switch 2/8V, Administrator'S Manual, Page: 215 / 465

Fabric OS 5.3.0 administrator guide 217
10 Routing traffic
About data routing and routing policies
Data moves through a fabric from switch to switch and storage to server along one or more paths that
make up a route . Routing policies determine the correct path for each frame of data.
Whatever routing policy a switch is using applies to the VE_Ports as well. Refer to ” Using the FC-FC routing
service ” on page 227 for details about VE_Ports.
CAUTION: For most configurations, the default routing policy is optimal, and provides the best
performance. You should only change the policy if there is a performance issue that is of concern, or a
particular fabric configuration requires it.
The following routing policies are available to tune routing performance:
•
Exchange-based
routing
The choice of routing path is based on the SID, DID, and Fibre Channel originator exchange ID (OXID),
optimizing path utilization for the best performance. Thus, every exchange can take a different path
through the fabric. Exchange-based routing requires the use of the Dynamic Load Sharing (DLS) feature;
when these policies are in effect, you cannot disable the DLS feature.
• Port-based routing
The choice of routing path is based only on the incoming port and the destination domain. To optimize
port-based routing, the Dynamic Load Sharing feature (DLS) can be enabled to balance the load across
the available output ports within a domain.
Using port-based routing, you can assign a
static route
, in which the path chosen for traffic never
changes. In contrast, exchange-based routing policies always employ
dynamic path selection
.
Port-based routing is supported by all models.
Specifying the routing policy
The following routing policies are supported:
• Port-based path selection
Default on SAN Switch 2/8V, SAN Switch 2/16V, SAN Switch 2/32, SAN Director 2/128, and
4/256 SAN Director (using configuration option 1). These switches support the port-based policy only;
you cannot change the routing policy for these switches. 4/16 SAN Switch and 4/8 SAN Switch,
Brocade 4Gb SAN Switch for HP p-Class BladeSystem, Brocade 4Gb SAN Switch for HP c-Class
BladeSystem, SAN Switch 4/32, SAN Switch 4/32B, 4/64 SAN Switch, 400 MP Router, and 4/256
SAN Director (using configuration option 5) switches can also use port-based routing.
• Exchange-based path selection
Default on 4/16 SAN Switch and 4/8 SAN Switch, Brocade 4Gb SAN Switch for HP p-Class
BladeSystem, Brocade 4Gb SAN Switch for HP c-Class BladeSystem, SAN Switch 4/32, SAN Switch
4/32B, 4/64 SAN Switch, 400 MP Router, and 4/256 SAN Director (using configuration option 5).
Refer to ”
Configuring Directors ” on page 109 for more details about 4/256 SAN Director
configuration options.
You can use the
aptPolicy
command to display and specify a different routing policy. The
aptPolicy
command detects the switch’s configuration options and provides the appropriate policies
for users to select from. For example, if you attempt to set the policy for the 4/256 SAN Director using
configuration option 1, an error message is returned because you cannot change the routing policy.
Refer to the Fabric OS Command Reference Manual for more details on the
aptPolicy
command.
You must disable the switch before changing the routing policy, and re-enable it afterward.