Technical data

Fabric OS Administrator’s Guide 6-3
Publication Number: 53-0000518-09
Assigning a Static Route
6
Assigning a Static Route
A static route can be assigned only when the active routing policy is port-based. When device-based or
exchange-based routing is active, you cannot assign static routes. Thus, the SilkWorm 48000 using
configuration option 5 does not support static routing.
To assign a static route, use the uRouteConfig command. To remove a static route, use the
uRouteRemove command
Specifying Frame Order Delivery
The order of delivery of frames is maintained within a switch and determined by the routing policy in
effect. Following are the frame delivery behaviors for each routing policy.
• Port-based routing
All frames received on an ingress port destined for a destination domain are guaranteed to exit the
switch in the same order in which they were received.
• Device-based routing
All frames received on an ingress port between the same two fabric devices are guaranteed to exit
the switch in the same order in which they were received. This policy maintains the order of frames
across exchanges between the fabric devices as well.
• Exchange-based routing
All frames received on an ingress 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.
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.
By default, out-of-order frame-based delivery is allowed to minimize the number of frames dropped.
You should only force in-order frame delivery across topology changes if the fabric contains destination
devices that cannot tolerate occasional out-of-order frame delivery.
N
ote
SilkWorm 3900, 12000, 24000, and 48000 (using configuration options 1 through 4):
When you enter the uRouteConfig command, two similar warning messages might 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 reestablish the static route, potentially causing a
conflict.