T1-F Interface; Overview; Configuring A T1-F Interface - 3Com MSR 50 Series Configuration Manual

T1-F Interface

Overview

Configuring a T1-F
Interface
T1-F interfaces, fractional T1 interfaces, are simplified CT1/PRI interfaces. They are
a cost-effective alternative to CT1/PRI interfaces where T1 access does not need
multiple channel sets or ISDN PRI.
Compared with a CT1/PRI interface, a T1-F interface delivers these features:
In framed mode, it can bind timeslots into only one channel set, while a
■
CT1/PRI interface can group and bundle timeslots randomly into multiple
channel sets.
It does not support PRI mode.
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A T1 line is multiplexed from 24 channels. That is, a T1 primary group frame DS1
(digital signal level-1) comprises 24 DS0 (64 kbps) timeslots and 1 framing bit for
synchronization, with each timeslot being 8 bits. Each primary group frame thus
has 193 bits (24 × 8+1). As DS1 can transmit 8000 frames per second, its
transmission speed is 1544 kbps (193 × 8 kbps).
A T1-F interface can only work in framed mode. Timeslots 1 through 24 on it can
randomly form a channel set. The rate of the interface is thus n × 64 kbps or n ×
56 kbps and its logical features are the same as those of a synchronous serial
interface where you can configure PPP, FR, LAPB and X.25 at the data link layer
and IP or IPX at the network layer.
Follow these steps to configure a T1-F interface:
To do...
Enter system view
Enter T1-F interface view
Bundle timeslots on the
interface into a channel set
Set the cable length and
attenuation
Set the line code format
Set the clock mode
Enable user data inversion
Use the command...
system-view
interface serial
interface-number
ft1 timeslot-list range
[ speed { 56k | 64k } ]
ft1 cable { long decibel |
short length }
ft1 code { ami | b8zs }
ft1 clock { master | slave }
ft1 data-coding { inverted |
normal }
T1-F Interface 117
Remarks
--
--
Required
If no timeslot range is
specified, all timeslots are
bundled into one channel set.
The default timeslot speed is
64 kbps, and the default T1-F
interface speed is 1536 kbps.
Optional
The long 0db keyword
applies by default.
Optional
The default is B8ZS.
Optional
The default is slave, that is,
line clock.
Optional
Disabled by default.