EMC Symmetrix DMX-3, Product Manual

Page: 95 / 326

Channel attachments 95
Symmetrix DMX-3 Hardware
ESCON channel
interface
connections The Symmetrix DMX-3 ESCON directors connect to mainframe hosts.
The eight-port, four-processor ESCON director provides the
capability for four concurrent operations through its four physical
interfaces for communicating with the serial channels in host
systems.
Note: “ESCON channel directors” on page 79 contains more information on
the ESCON director.
ESCON channels use fiber optic cables. These serial channels are
formally called the ESA/390 Enterprise Systems Connection
Architecture (ESCON) I/O interface. The serial channels use
point-to-point or switched point-to-point links. Each link has two
physical fibers for transporting data: one for inbound signals and one
for outbound signals. The current ESCON implementation supports
data transfer rates up to 17 MB/s.
There are two types of fiber optic cables: multimode and
single-mode. Multimode cables support a maximum link of
1.86 miles (3 km). Single-mode cables support a maximum link of
12.42 miles (20 km) with the Extended Distance Feature (XDF).
Note: Symmetrix systems directly connect to ESCON multimode cables only.
In the ESCON environment, a link connects a host serial or ESCON
channel with a Symmetrix serial channel (ESCON) interface. This link
can be a direct connection between the processor, or LPAR, and the
serial channel interface. This link can also have up to two ESCON
Directors configured between the processor, or LPAR, and the serial
channel interface. The Symmetrix system supports a maximum
connection length of 26.7 miles (43 km) with two single-mode cables
and one multimode cable.
Figure 18 on page 96 illustrates several types of ESCON channel
attachments. Table 22 on page 97 describes cable types and supported
distances.