- Enterasys Security Router User's Guide

XSR User’s Guide 4-1
4
Configuring T1/E1 & T3/E3 Interfaces
Overview
The XSR provides Frame Relay and PPP service via T1/E1 and T3/E3 functionality as well as
Drop and Insert features.
T1/E1 Functionality
The XSR provides a T1/E1 subsystem on a single NIM-based I/O card with a maximum of two
installed NIMs. Depending on the card type and series, each card can support 1, 2 or 4 T1 or E1
physical ports.
You can select either T1, at 1.544 Mbps interface rate per port, or E1, at 2.048 Mbps interface rate
per port. In both operational modes, the interface can work either in full rate T1/E1 mode (the
complete available line interface rate is assigned to one user), fractional T1/E1 mode (only one
channel group is assigned, with less than the total available number of timeslots on a T1/E1 line
configured per physical port) or in channelized mode (more than one channel group is configured
per physical port).
In fractional/channelized mode, up to 31 DS0 channels can be assigned on E1 interfaces and up to
24 DS0 channels can be assigned on T1 interfaces. The rate (line speed) of basic channel (DS0) can
be configured at 56 or 64 Kbps.
T3/E3 Functionality
The XSR T3/E3 subsystem offers a NIM-based I/O card with a single port, full rate unchannelized
T3/E3 mode and sub-rate support for proprietary T3 and E3 DSU vendors. “Sub-rate T3/E3” and
“fractional T3” are interchangeable terms describing un-channelized T3/E3 service that delivers
less than full line bandwidth.
T3 or E3 mode is software selectable - one hardware NIM supports both modes.
Features
T1/E1 Mode
The following features are offered on the T1/E1 interfaces:
•Integrated CSU/DSU
• Full-rate, channelized and fractional
• Short and long haul symmetrical line interfaces with 100/120 ohm impedance using RJ-45/
48C or 49C connectors