performance. You should change the routing policy only if there is a performance issue that is of concern,
or if a particular fabric configuration requires it.
Displaying the current routing policy
Connect to the switch and log in as admin.
Enter the aptPolicy command with no parameters.
The current policy is displayed, followed by the supported policies for the switch.
In the following example, the current policy is exchange-based routing (3) with the additional AP
dedicated link policy.
Current Policy: 3 1(ap)
3 0(ap): Default Policy
1: Port Based Routing Policy
3: Exchange Based Routing Policy
0: AP Shared Link Policy
1: AP Dedicated Link Policy
The choice of routing path is based on the Source ID (SID), Destination ID (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 this policy is in effect, you cannot disable the DLS feature.
Exchange-based routing is also known as Dynamic Path Selection (DPS). DPS is where exchanges or
communication between end-devices in a fabric are assigned to egress ports in ratios proportional to the
potential bandwidth of the ISL or trunk group. When there are multiple paths to a destination, the input
traffic will be distributed across the different paths in proportion to the bandwidth available on each of the
paths. This improves utilization of the available paths, thus reducing possible congestion on the paths.
Every time there is a change in the network (which changes the available paths), the input traffic can be
redistributed across the available paths. This is a very easy and non-disruptive process when the
exchange-based routing policy is engaged.
The choice of routing path is based only on the incoming port and the destination domain. To optimize
port-based routing, DLS can be enabled to balance the load across the available output ports within a
Using port-based routing, you can assign a static route, in which the path chosen for traffic does not
change when a topology change occurs unless the path becomes unavailable. If the static route violates
FSPF, it is not used. In contrast, exchange-based routing policies always employ DPS.
For FC routers only: When an FC router is in port-based routing mode, the backbone traffic is
load-balanced based on SID and DID. When an FC router is in exchange-based routing mode, the
backbone traffic is load-balanced based on SID, DID, and OXID.
Whatever routing policy a switch is using applies to the VE_Ports as well. See Chapter 21,
and monitoring FCIP extension
For most configurations, the default routing policy is optimal and provides the best
services" on page 457 for details about VE_Ports.
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