HP AE370A HP StorageWorks Fabric OS 6.x administrator guide (5697-0015, May 20 - Page 204

option 1, an error message is returned because you cannot change the routing policy. See the Fabric OS Command Reference for more details on the aptPolicy command. You must disable the switch before changing the routing policy, and re-enable it afterward. Assigning a static route A static route can be assigned only when the active routing policy is port-based and running on an HP StorageWorks 4/8 SAN Switch, 4/16 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, or 4/256 SAN Director (using configuration option 1). When exchange-based routing is active, you cannot assign static routes. Even if the active routing policy is port-based, you cannot assign static routing to the 4/64 SAN Switch, 400 Multi-protocol Router. 4/256 SAN Director (using configuration option 5), or DC Director. To assign a static route, use the uRouteConfig command. To remove a static route, use the uRouteRemove command. NOTE: For the 4/256 SAN Director (using configuration option 1): When you enter the uRouteConfig command, two similar warning messages may display if a platform conflict occurs. The first message displays when the static routing feature detects the conflict. The second message displays when the Dynamic Load Sharing feature detects the condition as it tries to rebalance the route. A platform conflict occurs if a static route was configured with a destination port that is currently down. The static route is ignored in this case, in favor of a normal dynamic route. When the configured destination port comes back up, the system attempts to re-establish the static route, potentially causing a conflict. Specifying frame order delivery The order of delivery of frames is maintained within a switch and determined by the routing policy in effect. The frame delivery behaviors for each routing policy are: • Port-based routing All frames received on an incoming port destined for a destination domain are guaranteed to exit the switch in the same order in which they were received. • Exchange-based routing All frames received on an incoming port for a given exchange are guaranteed to exit the switch in the same order in which they were received. Because different paths are chosen for different exchanges, this policy does not maintain the order of frames across exchanges. If even one switch in the fabric delivers out-of-order exchanges, then exchanges are delivered to the target out-of-order, regardless of the policy configured on other switches in the fabric. NOTE: Some devices do not tolerate out-of-order exchanges; in such cases, use the port-based routing policy. In a stable fabric, frames are always delivered in order, even when the traffic between switches is shared among multiple paths. However, when topology changes occur in the fabric (for example, if a link goes down), traffic is rerouted around the failure, and some frames could be delivered out of order. Most destination devices tolerate out-of-order delivery, but some do not. Use of out-of-order frame-based delivery can minimize the number of frames dropped, while enabling in-order delivery (IOD) guarantees that frames are either delivered in order or dropped. All HP B-series switches enable IOD by default to ensure frames are delivered in order, as not all HP destination devices can tolerate out-of-order frames. To disable in-order frame delivery across topology changes: 204 Routing traffic