Cisco OSM-12CT3/T1 - Optical Services Module Multiplexor, OSM-12CT3, OSM-12CT1 Configuration

CHAP T E R

7

Configuring the Channelized 12-port CT3/T1
Optical Services Modules

This chapter describes how to configure the 12-port channelized/unchannelized DS3 Optical Services
Modules (OSM-12CT3/T1).

The chapter consists of these sections:

• Understanding the Channelized/Unchannelized CT3/T1 Modules, page 7-1

• Supported Features, page 7-2

• Configuring the Interfaces, page 7-6

Understanding the Channelized/Unchannelized CT3/T1 Modules

The OSM-12CT3/T1 module provides 12DS3 interface connections using mini-SMB connectors.

Each DS3 port can be independently configured all the way from a clear channel DS3 down to and
including DS1, E1,and DS0 connections on the same port, with a maximum of 128 channels per DS3
port.

Each OSM-12CT3/T1 can support any combination of DS3/DS1/E1/T1s up to 1023 channels. For
example, each port can support the following:

• 1 DS3 at 44.7 Mbps

• 21 E1s at 2.048Mbps

• 28 DS1s at 1.5 Mbps

• 128 DS0s at 64 Kbps

An unchannelized DS3 connection provides a single serial interface data channel that may be configured
to use all of the DS3 bandwidth or a fractional portion of it. This mode is compatible with several
vendors of fractional (subrate) DS3 data service units (DSUs).

A cost, depending on the bandwidth, is associated with a serial interface. The total cost possible for 12 DS3

ports is 4096. That is, the sum of the costs of all the serial interfaces configured on 12 DS3 ports must be no

more than 4096. The show controller t3 command displays the VC cost, which indicates the available cost

of 12 DS3 ports. Tab le 7-1 shows the cost associated with each link type.

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Supported Features

Table 7-1 Serial Interface Cost

Link Type Cost

DS3 336

Unframed E1 16

1-6 DS-/TS 4

7-9 DS0/TS 6

10-16 DS0/TS 8

17-24 DS0/TS 12

25-31 TS 16

Channelized DS3 Overview

In the channelized mode of operation, an OSM-12CT3/T1 link is channelized into 28 DS1 or 21 E1 data
lines in an industry standard multiplexing format.

Each of the DS1 lines contain 24 timeslots of 64 or 56 kbps each, and each of the E1 lines contain 32
timeslots of 64 or 56 kbps each. The DS1and E1 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 lines are filled with an idle channel pattern.

Chapter 7 Configuring the Channelized 12-port CT3/T1 Optical Services Modules

Unchannelized DS3 Overview

In the unchannelized mode of operation, a DS3 link provides a single high speed user data channel,
rather than being multiplexed into 28 DS1 or 21 E1 lines. The data channel appears to the system as a
serial interface that may be configured to use the full DS3 bandwidth or a smaller portion of the DS3
bandwidth.

In unchannelized DS3 mode, the OSM-12CT3/T1 supports the maintenance data link (MDL) channel
when using c-bit parity framing as well as local and network loopbacks.

Supported Features

The 12-port channelized/unchannelized DS3 OSMs support the following features:

• General Features, page 7-3

• Serial Encapsulation Protocols, page 7-3

• DSU Mode, page 7-4

• T1 Configuration Options, page 7-4

• E1 Configuration Options, page 7-4

• DS3 Alarms, page 7-5

• Network Management, page 7-5

• Quality of Service Protocols, page 7-5

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Chapter 7 Configuring the Channelized 12-port CT3/T1 Optical Services Modules

General Features

The general features are as follows:

• Channelized DS3 with 28 DS1 lines or 21 E1 lines multiplexed into a DS3 line.

• C-bit parity, M23, and auto-detect framing.

• Internal clocking configurable.

• Bit error rate test (BERT) diagnostics for each DS-3 channel

• Local, line, and remote loopback.

• Generation and termination of DS-3 maintenance data link (MDL) in C-bit framing.

• Compliance with ANSI T1.231-1993, Bellcore GR820, ANSI T1.107, ANSI T1.403 1989, G.703

Section 2, G.704 Section 3, AT&T Pub. 62411 1990, and Facilities Data Link (ANSI T1.403 and
AT&T 54016).

Serial Encapsulation Protocols

The OSMs support for the following serial encapsulation protocols:

• Point-to-Point Protocol (PPP)

Supported Features

• Distributed Multilink PPP (dMLPPP)

The OSM-12CT3/T1 module supports dMLPPP, which means that the MLPPP encapsulation is
performed on the OSM-12CT3/T1 module rather than the route processor. The following dMLPP
features are supported:

–

336 bundles per module

–

A maximum of 12 DS1/E1 channels per bundle

–

All links in a bundle should operate at the same speed

–

100 ms of differential delay

• High-Level Data Link Control (HDLC)

• Frame Relay

Configure the OSM-12CT3/T1 interfaces for Frame Relay as described in the Cisco IOS Wide-Area
Networking Configuration Guide, Release 12.1 under “Configuring Frame Relay” and in the Cisco
IOS Wide-Area Networking Command Reference, Release 12.1 at:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/wan_c/wcdfrely.htm

http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/wan_r/wrdfrely.htm

Configure traffic shaping for Frame Relay as described in the Cisco IOS Quality of Service

Solutions Configuration Guide under “Configuring Distributed Traffic Shaping” at:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fqos_c/fqcprt4/qcfdts.h
tm.

For information on Multilink Frame Relay (FRF.16), see •Multilink Frame Relay (FRF.16),

page 1-4.

• MPLS/VPN

For MPLS/VPN configuration information, see Chapter 9, “Configuring Multiprotocol Label

Switching on the Optical Services Modules.”

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Supported Features

DSU Mode

Unchannelized DS-3 supports subrate and scrambling formats for the following DSUs.

• Digital Link

• Ve ri l in k

• 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.

Chapter 7 Configuring the Channelized 12-port CT3/T1 Optical Services Modules

• 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.

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Fractional E1 lines contain only a single logical channel group that can be either a single 64-kbps
timeslot or a range of timeslots; for example timeslot 1, or timeslots 15-23. Any unused timeslots
are filled with programmable idle-channel data.

Note If you assign only one channel group to an E1 line, it is a fractional E1 line. If you assign

more than one channel group to an E1 line, it is a channelized E1 line.

• Unframed E1—Any of the 21 E1 lines can be configured as unframed E1 data lines. Each unframed

E1 line contains no framing overhead and is not timeslot divided.

Note For channelized, fractional, and unframed configurations each configured channel group, which might

contain individual timeslots and/or ranges of timeslots, uses only one of the 128 available logical
channels. For example, if you assign the range of timeslots 3-7 to a channel group, only one logical
channel is used. Likewise, if you assign just timeslot 3 to a channel group, only one logical channel is
used.

DS3 Alarms

Supported Features

This section lists the supported DS3 alarms:

• Alarm indication signal (AIS)

• Out of frame (OOF)

• Far End Remote Failure (FERF)

• Loss of Signal (LOS)

• Far End Block Errors (FEBE)

• Far-End Alarm and Control (FEAC) support

Network Management

This section lists the supported network management features:

• Local Loopback.

• Network Loopback.

• RFC 1407 MIB support.

Quality of Service Protocols

For information on configuring QoS on the Channelized OSMs, refer to Chapter 10, “Configuring QoS

on the Optical Services Modules.”

The following QoS features are supported on the Channelized OSMs:

• Hierarchical traffic shaping for Frame Relay, HDLC, and PPP encapsulations

• PFC2 QoS on the LAN and WAN ports

• Differentiated Services Control Point (DSCP)

• IP Precedence classification

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