Page 146 - Optical Switching And Networking Handbook

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Optical Switching Systems and Technologies 131

The most critical and underappreciated aspect of the metropolitan
WDM market is the enterprise access market. WDM systems link
major corporate data centers with remote locations, offsite storage
facilities, disaster recovery and alternate sites, or data warehouses.
The main types of interconnection are as follows:
ESCON For legacy mainframe data applications.

Fiber Channel Legacy services benefit metropolitan-area
network (MAN) services interconnecting FDDI networks and
ATM services across town.
Gigabit Ethernet (soon 10 Gigabit Ethernet) Applications for
high-speed transparency across the environment are also crucial
for storage-area networking (SAN) needs.
Storage-area networks Enterprises increasingly need to
interconnect SAN islands in different locations. SANs are being
located in different sites for both operational and cost reasons,
such as better alignment with distributed enterprise data,
enhanced survivability, and lower costs for storage facilities
located outside metropolitan centers.
Without interconnected SANs, enterprises are forced to perform
data protection and data recovery using manual tape backup and
vault storage. The interconnection of SAN islands with high band-
width, high reliability, and low latency will enable a variety of stor-
age applications across the extended SANs, including

Remote backup/tape vaulting
Batch replication
Disaster recovery

Synchronous replication
Without DWDM, each of these applications consumes a single
fiber for each connection. This would be extremely expensive to pro-
vision and wasteful in the overall scheme of the providers’ networks.
Many organizations require at least one or more of these applica-
tions. Some require tens of these connections across an enterprise
connection in a metropolitan area. Banks, health care facilities,