RuggedCom RuggedRouter RX1100 - Manual (Page 67)

7. Configuring Frame Relay/PPP And T1/E1
Revision 1.14.3 67 RX1000/RX1100™
7. Configuring Frame Relay/PPP And T1/E1
7.1. Introduction
This chapter familiarizes the user with:
• Frame Relay and PPP Terminology and Issues
• Configuring Frame Relay and PPP Links
• Viewing status and statistics
• Upgrading Firmware
7.1.1. T1/E1 Fundamentals
A T1 is a communications circuit upon which has been imposed a digital signal 1 (DS1) signaling
scheme. The scheme allows 24 "timeslots" of 64 Kbps DS0 information (as well as 8 Kbps of signaling
information) to be multiplexed to a 1544 Kbps circuit.
The 24 DS0s can be used individually as standalone channels, bonded into groups of channels or can
be bonded to form a single 1536 Kbps channel, referred to as a clear channel. Not all channels need
be used. It is quite common to purchase N channels of 64Kbps bandwidth and leave the remainder
unused, this is known as fractional T1.
The telephone network terminates the T1 line and maps each of the channels through the T1 network
to a chosen T1 line. Individual and bonded DS0s from more than one remote T1 can be aggregated
into a full T1 line (often referred to as central site concentration).
Whereas the T1 line itself is referred to as the physical interface, groups of DS0s form channels and
the protocols that run on the channels are known as a logical interfaces. The RuggedRouter provides
you the ability to operate Frame Relay or PPP over your logical interfaces.
An E1 is is a communications circuit conforming to European standards, possessing 32 64 Kbps
channels, of which one is usually reserved for signaling information.
7.1.1.1. Frame Relay
Frame Relay is a packet switching protocol for use over the WAN. The RuggedRouter provides the
ability to construct point-to-point IP network connections over Frame Relay.
Each Frame Relay interface provides a link between a local and peer station. One of the stations
must be configured as a Data Communications Equipment (DCE) device (often known as the Switch)
while the peer station must be configured as a Data Terminal Equipment (DTE) device (often known
as Customer Premises Equipment (CPE)). The DCE is responsible for managing the link, advertising
connections to the DTE and switching packets between connections. The DTE raises individual
connections and sends data on them.
When using a T1/E1 line to access a public Frame Relay provider, configure the Router as a DTE.