Specifications

Chapter 1. Introduction 3

Figure 1-1 Fibre Channel Link

An FC link (port-to-port connection) can be:

򐂰 Node-to-node (N_Port-to-N_Port)

򐂰 Node-to-switch (N_Port-to-F_Port)

򐂰 Switch-to-switch (E_Port-to-E_Port)

The FC link data rate is 1 Gbps (100 MBps) for zSeries and 9672 G5/G6 FICON feature

ports, and 1 Gbps or 2 Gbps (200 MBps) for zSeries FICON Express feature ports. The

2 Gbps link capability is auto-negotiated between the zSeries server and FICON Director, as

well as the Director and devices, and is transparent to the operating system and application.

With devices in general, the zSeries FICON Express, FICON Director, and/or device

communicate and agree upon either a 1 Gbps or 2 Gbps (100 MBps or 200 MBps) link speed.

This speed determination is based upon the adapter speeds in the zSeries server, FICON

Director, and device, as well as the fiber optic cable infrastructure capabilities. For those parts

of the I/O infrastructure that are not 2 Gbps link-capable, the link speed will be

auto-negotiated to 1 Gbps (100 MBps).

World-Wide Names (WWN)

As mentioned, nodes and ports have unique 64-bit addresses that identify them in an FC or

FICON topology. These addresses are assigned by the manufacturer, with a vendor-specific

portion defined by the IEEE standards committee. These addresses (in the FC standard) are

called Node_Names and Port_Names, and when they are world-wide unique, they are

referred to as:

򐂰 World-Wide Node_Name (WWNN)

򐂰 World-Wide Port_Name (WWPN)

A WWN (any WWNN or WWPN) is usually written in sets of two hex digits, separated by

colons (for example, 08:45:12:56:43:00:D5:A0). Figure 1-2 illustrates the use of WWNs.

Note: The 2 Gbps line speed is the theoretical maximum unidirectional bandwidth

capability of the fiber link. The actual throughput potential of the 2 Gbps link (whether it is

measured in I/O operations per second, or MBps) will depend on the type of workload,

fiber infrastructure, and storage devices in place.

Fibre Channel link

Outbound

InboundInbound

FC port