Specifications

Appendix A
78
A.7.1 Functional Details
Fiber
The E1/T1 fiber modem uses a proprietary scrambled NRZ optical line coding to provide extremely low BER for
E1 over fiber.
The electrical interface is an unbalanced 75 ohm for the BNC model or balanced twisted pair on industry
standard USOC RJ48C wiring on a physical shielded RJ-45. In T1 mode, only unframed, clear channel
transmissions are supported. In E1 mode, however, both transparent unframed and fractional (nx64) E1 are
supported. The payload timeslots are assigned consecutively from a starting timeslot and continue through the
number of timeslots assigned. Random timeslot assignment is not supported.
Management
The FRM220-E1/T1 has a small processor that is used to read the on-board DIP switches. When used stand-
alone, the configuration can be done via the DIP switches or through a text based menu driven console when the
card is placed in the CH01M with DB9.
When placed in a managed chassis, such as our FRM220-CH20 with NMC (Network Management Controller),
the E1/t1 card and remote are configured and monitored through the chassis NMC via console, Telnet, Web HTTP
or SNMP.
1. Stand-alone – DIP settings when placed in CH01. Serial console when placed in CH01M
2. Rack management - When placed in NMC managed rack, all other settings can be overridden by the NMC management.
3. E1/T1 supports in-band management.
A.7.2 Panel
Figure A.7.1 Panel designations of FRM220-E1/T1
There are four variations of this media converter. The E1/T1 with RJ-45 comes with either a fixed optical
transceiver or in a version that supports pluggable SFP optics. The E1 only with BNC also comes in either a fixed
optical transceiver or in an SFP version.
LED Indicators
Power
FX Link
E1 Sig
Test