Configuration Guidelines
A–3
Digital Confidential
•
Maximum length of the transceiver cable cannot exceed 50 meters (164 feet).
This maximum length can be decreased due to the internal cabling equivalen-
cy of a device (such as a DELNI) that is connected between the bridge and
the transceiver, or due to the use of an office transceiver cable. The cabling
equivalency of such a device must be subtracted from the 50-meter (164-foot)
maximum. Note that the DECbridge 500/600 series does not have an internal
cabling equivalency.
Cabling equivalency is a measure of the internal timing delay of a device expressed
in meters of transceiver cable.
For example:
–
If a device has a 5-meter (16.4-foot) cabling equivalency, then its maxi-
mum allowable transceiver cable length is 50 meters (164 feet) minus 5
meters (16.4 feet) or 45 meters (148 feet).
–
Office transceiver cable (BNE4x-xx), due to its smaller diameter, has a
signal loss that is four times that of the (BNE3x-xx) transceiver cable. If
office transceiver cable is used, the maximum transceiver cable distance
must be divided by 4. Thus, the maximum office transceiver cable length
allowed is 12.5 meters (41 feet).
If the configuration includes a device and the device has any internal cab-
ling equivalency, this should be subtracted from the 50-meter (164-foot)
maximum before dividing by 4. For example, if a device has a 10-meter
(32.8-foot) cabling equivalency and is attached to its transceiver using
office transceiver cable, then the maximum allowable transceiver length
is 50 meters (164 feet) minus 10 meters (32.8 feet) divided by 4. The
arithmetic result yields 10 meters (32.8 feet).
For device-specific information related to cabling equivalency, refer to
the DECconnect System Planning and Configuration Guide.
•
When connecting the bridge to a configuration that includes a DELNI, allow
5 meters (16.4 feet) cabling equivalency loss for the DELNI.
