Channels - HP ProCurve Secure 7000dl Series Basic Management And Configuration Manual

Configuring E1 and T1 Interfaces
ProCurve Secure Router Modules
4-12
The settings that you must configure in order to establish an E1 or T1 WAN
connection are explained in the following sections.

Channels

As mentioned earlier, E1- and T1-carrier lines provide different transmission
speeds. An E1-carrier line provides 2.048 Mbps in total bandwidth, which is
divided into 32 channels. A T1-carrier line, on the other hand, provides 1.544
Mbps in total bandwidth, which is divided into 24 channels.
Called digital signal zero (DS0), each channel operates at 64 Kbps, the amount
of bandwidth required to transmit a single analog voice call through a digital
telecommunications network. The channels in these dedicated circuits are
created using time division multiplexing (TDM). By combining, or multiplex-
ing, multiple channels into a larger, more complex signal, TDM creates a high-
bandwidth channel. (See Figure 4-6.)
32 or 24 DS0s
MUX
DS0 channels
multiplexed into E1 or T1
Figure 4-6. Multiplexing Multiple Channels into One E1- or T1-Carrier Line
Each channel receives an equal time slice within the complex signal in a
rotating, repeating sequence and thus receives an equal amount of bandwidth.
On the receiving end, TDM is used to recover the original signals through a
reverse process called demultiplexing.
E1 Channels. When you configure an E1 module with a built-in DSU, you
must configure the number of channels that the E1 WAN connection uses. You
can configure channels 1-31. One channel—channel 0—is used to maintain
the connection and cannot be used for data or voice.
If you purchase an entire E1-carrier line, you configure channels 1-31. If you
purchase a fractional E1-carrier line, your public carrier will tell you which
channels to configure for that connection. (If you want to use some of the
channels for voice, see Chapter 9: Configuring the E1 + G.703 and T1 +
DSX-1 Modules.)
E1- or T1-carrier line
E1 or T1 demultiplexed
into DS0 channels
32 or 24 DS0s
MUX