7-4
Optical Services Modules Installation and Configuration Note, 12.2SR
OL-9465-03
Chapter 7 Configuring the Channelized 12-port CT3/T1 Optical Services Modules
Supported Features
DSU Mode
Unchannelized DS-3 supports subrate and scrambling formats for the following DSUs.
•
Digital Link
•
Verilink
•
Adtran
•
Larscom
•
Kentrox
T1 Configuration Options
The T1 lines have the following configuration options:
•
Local, line, and remote loopback.
•
Generation and termination of DS-3 maintenance data link (MDL) in C-bit framing.
•
In T1 mode, the channelized CT3/T1 OSMs support facilities data link (FDL) in Extended
Superframe (ESF) framing, as well as various loopbacks. Bit error rate testing (BERT) is supported
on each of the T1 lines. It can be done over a framed or unframed DS-1 signal. The
OSM-ChOC12C/T1 module has four framers, each connected to three contiguous ports. BER testing
can be done simultenously on 6 T1 interfaces in addition to any DS3 interfaces configured on the
three ports to which a framer is connected.
•
In the channelized mode of operation, a channelized CT3/T1 OSM link can be channelized into
maximum of 336 T1 data lines in an industry standard multiplexing format. Each of the T1 lines
contains 24 timeslots of 64 or 56 kbps each. The T1 lines can support one or more user data
channels, which appear to the system as serial interfaces. Each serial interface is assigned one or
more of the timeslots giving the serial interface a bandwidth of
n
x 56 kbps or
n
x 64 kbps, where
n
is the number of timeslots assigned. Any unused timeslots of the T1 are filled with an idle channel
pattern.
E1 Configuration Options
The E1 lines have the following configuration options:
•
Channelized E1—Any of the 21 E1 lines can be configured as channelized E1 lines, but you are
limited to a total of 128 logical channels. You can group the time slots in these E1 lines into several
individual logical channel groups, each of which carries data with different data link layer protocol
encapsulations. You can configure timeslot 16 as a data channel, although it is typically used for
common channel signaling. (Channel associated signaling (CAS) for voice channels and E1
Facilities Data Link [FDL] on timeslot 16 are not supported.)
•
Each logical channel group can be composed of individual 64-kbps timeslots and/or ranges of
timeslots, for example, 1, 9, 12-14. Each logical channel group can contain from 1-31 timeslots
maximum; the same timeslot cannot be used in more than one logical channel group. Any unused
timeslots are filled with programmable idle-channel data.
•
Fractional E1— Any of the 21 E1 lines can be configured as fractional E1 lines, each of which can
be either E1 frames or E1 cyclic redundancy check (CRC) multiframes, as specified by CCITT/ITU
G.704 and G.706. A fractional E1 line is a subset of the full E1 bandwidth, which uses
n
x 64 kbps;
where
n
is a timeslot in the range of 1-31.
