Users Guide

Fabric OS Administrator’s Guide 123

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Routing policies

Port-based

routing

The choice of routing path is based only on the incoming port and the destination domain. To

optimize port-based routing, Dynamic Load Sharing (DLS) can be enabled to balance the load

across the available output ports within a domain.

NOTE

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. For more information on

VE_Ports, refer to the Fibre Channel over IP Administrator’s Guide.

Exchange-based routing

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). For more information on

DPS refer to “Dynamic Path Selection” on page 124.

Device-based routing

Device-based routing optimizes routing path selection and utilization based on the Source ID (SID)

and Destination ID (DID) of the path source and destination ports. As a result, every distinct flow in

the fabric can take a different path through the fabric. Effectively, device-based routing works the

same as exchange-based routing but does not use the OXID field. This helps to ensure that the

exchanges between a pair of devices stay in order.

NOTE

Device-based routing requires the use of Dynamic Load Sharing (DLS); when this policy is in effect,

you cannot disable the DLS feature.

Device-based routing is also a form of Dynamic Path Selection (DPS). For more information on DPS

refer to “Dynamic Path Selection” on page 124.

NOTE

Device-based routing is supported in FICON environments, and in open environments only when

FICON coexists.