McDATA StorageWorks 2/140 - Director Switch Planning Manual page 186

Implementing SAN Internetworking Solutions
4
McDATA Products in a SAN Environment - Planning Manual
4-44
• Does not require Fibre Channel BB_Credits assigned to the link
because buffering is built in to the GFP function to enable
long-distance transmission of storage traffic.
• Creates a routed iSAN or one logical Fibre Channel fabric through
a stretched E_Port connection, depending upon the protocol and
if one or more SAN routers are deployed in the link.
— Native FCP or FICON (unrouted) - The top data path in
Figure 4-10 illustrates native FCP or FICON extended-distance
connectivity through an unrouted SONET interface. GFP
interfaces provide required link buffering and flow control.
The stretched E_Port connection is vulnerable to disruptions
caused by events at each site or to disruptions caused by
problems with the extended-distance SONET link.
— Native FCP (routed) - The middle data path in
illustrates native FCP extended-distance connectivity through
a routed SONET interface. GFP interfaces provide required
link buffering and flow control. A single Eclipse 2640 SAN
router at one end of the link provides R_Port connectivity and
SAN isolation (not intelligent port connectivity or protocol
conversion). The routed SAN connection ensures disruptions
at one site are isolated and not allowed to propagate to other
locations. This connection does not support FICON operation.
— iFCP (routed) - The bottom data path in
iFCP extended-distance connectivity through a routed SONET
interface. GFP interfaces provide SONET connectivity but are
not required for link buffering and flow control. Eclipse 1620
SAN routers at each end of the link provide intelligent port
connectivity and iFCP protocol conversion. The routed iSAN
connection ensures disruptions at one site are isolated and not
allowed to propagate to other locations. This connection does
not support native FCP or FICON operation.
Several network service providers provide metropolitan and intercity
SONET and SDH transport services. Long-distance SONET and SDH
circuits are common and the technology does not suffer the cost and
availability restrictions inherent to dark fiber and WDM. The
technology provides low overhead, high bandwidth, point-to-point
transport of storage traffic, and is a cost-effective choice for remote
data replication.
Figure 4-10
Figure 4-10 illustrates