IBM eServer zSeries 900 Technical Guide

112 IBM eServer zSeries 900 Technical Guide

FICON FCTC support via Cascaded Directors

FICON native (FC) channels on the zSeries servers support cascaded Fibre Channel

Directors. This support is for a two-Director configuration only. With cascading, a FICON

native (FC) channel, including the FICON channel-to-channel (FCTC) function, can connect a

server to a device or other server via two native connected Fibre Channel Directors. This

cascaded Director support, delivered in conjunction with IBM’s Fibre Channel Director

partners, is for all Native FICON channels implemented on FICON features on z900 servers,

and FICON Express features on z900 and z800 servers. See “FICON Support of Cascaded

Directors” on page 102.

For more information on the FCTC function, see the IBM Redpaper,

FICON CTC

Implementation

, REDP0158, available from:

http://www.ibm.com/redbooks

3.4.3 Migrating from ESCON to FICON connectivity

With FICON channels (in FCV mode), you can still preserve your ESCON control unit

investments; see Figure 3-19.

Figure 3-19 Migrating from ESCON to FICON

ESCON-to-FICON (FCV mode) migration allows:

򐂰 Fiber consolidation, reducing cable bulk between servers and 9032-005, since more

concurrent operations can use the same fiber (up to 8 for a FICON channel in FCV mode).

In ESCON, only one I/O operation at a time can use the fiber link.

򐂰 Greater fiber link unrepeated distances: 10 km (20 km with an RPQ) for FICON (FCV

mode) channels, compared with 3 km for ESCON channels.

򐂰 Performance droop is moved from 9 km for ESCON channels to 100 km for FICON

channels in FCV mode.

򐂰 Greater channel and link bandwidth per FICON channel in FCV mode. This is particularly

beneficial when you are channel-constrained.

򐂰 A larger number of device numbers (subchannels) are supported per FICON channel (in

FCV mode). There were up to 1024 devices supported on an ESCON channel; a FICON

channel (in FCV mode) supports up to 16384 devices.

CU CU CU

CU

CUCU CU CU CU

CU

CUCU

FICON

bridge

port

ESCON

port

ESCON Links

ESCON Links

ESCON Links

FC Links

LP 1 LP 2

LP 3

EMIF

LP 1 LP 2 LP 3

EMIF

CNC

FCV

9032-005

9032-005 9032-005 9032-005