ServerNet Cluster 6780 Planning and Installation Guide (G06.28+, H06.05+)

Table Of Contents
Using the Long-Distance Option
ServerNet Cluster 6780 Planning and Installation Guide527301-005
G-8
Using SCF to Specify the Distances Between Zones
Making the Zone-to-Zone Connections
When you use DWDMs as part of a zone-to-zone connection, the cables between the
switches and the DWDMs must be single-mode fiber-optic cables. To determine the
type of connections to be used between the DWDMs, refer to the documentation for
your DWDM.
If DWDMs are not used, you must use single-mode fiber-optic cables for the zone-to-
zone connections. Follow the guidelines in Connecting the Zone Cables on page 6-10.
Using SCF to Specify the Distances Between Zones
If all the zones in a three-zone cluster are separated by more than 5 kilometers, there
is no need to specify the distances explicitly. In this case, the External ServerNet SAN
Manager infers the distances from the configuration loaded on the switches and sets
data transfer parameters appropriate for long distances.
However, if a cluster has a mix of long and short-distance connections, this default
behavior does not necessarily optimize performance. To ensure that the message
system transfers data in the way most efficient for each connection, use the SCF
ALTER SUBSYS command to specify the distances between zones.
For information about ALTER SUBSYS and other SCF commands for ServerNet
Cluster, see the ServerNet Cluster 6780 Operations Guide.
Note. If DWDMs are not used, your service provider must perform margin testing on the
transceivers used for long-distance connections between 10 and 15 km. For more information
on the margin test and its requirements, your service provider should refer to hardware
technical bulletin TB20041.