IBM eServer zSeries 900 Technical Guide

124 IBM eServer zSeries 900 Technical Guide

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Transmission data checking

When a transmission is sent via an FCP channel, due to its full-fabric capability, FCP

performs intermediate data checking for each leg of that transmission. FICON (and

ESCON) also perform intermediate data checking, but with an added end-to-end checking

for enhanced quality of delivery.

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Serviceability

– Licensed Internal Code (LIC) updates

FCP allows for LIC updates, but requires a disruptive channel off/on in order to activate

them, whereas most FICON LIC updates can be performed concurrently without

impacting FICON channel operation.

– Problem determination

• Link Incident Reporting

Link Incident Reporting is integral to the FICON (and ESCON) architecture. When a

problem on a link occurs, this mechanism identifies the two connected nodes

between which the problem occurred, potentially leading to faster problem

determination and service. For FCP, Link Incident Reporting is not a requirement for

the architecture (though it may be offered as an optional switch function).

Consequently, important problem determination information may not be available

should a problem occur on an FCP link.

• Enterprise fabric

The use of FICON cascaded directors would ensure the implementation of a

high-integrity fabric. For FCP, a high integrity fabric solution is not required—

although strongly recommended, it is not mandatory. For example, should an FCP

Inter Switch Link (ISL) be moved, data could potentially be sent to the wrong

destination without notification. This type of error would not happen on an

enterprise fabric with FICON.

3.5.1 Connectivity

This section describes connectivity options available when using the FICON Express and

FICON features in FCP mode.

When configured for FCP mode, the features can access FCP devices in either of the

following ways:

򐂰 Via a FICON channel in FCP mode through a single Fibre Channel switch or multiple

switches to an FCP device

򐂰 Via a FICON channel in FCP mode through a single Fibre Channel switch or multiple

switches to a Fibre Channel-to-SCSI bridge

z900 FICON features

There are two types of transceivers supported on the z900 FICON Express and FICON

features: a long wavelength (LX) laser version and a short wavelength (SX) laser version.

This provides for four FICON channel features supported on the z900 server:

򐂰 z900 FICON Express LX feature (feature code 2319) with two ports per feature supporting

LC Duplex connectors

Note: z900 FCP channel direct attachment in point-to-point and arbitrated loop topologies

is not supported as part of the zSeries FCP enablement.