Alcatel Carrier Internetworking Solutions Omni Switch/Router User Manual

Page 997

Configuring an E1 Port

Page 33-9

2) Frame Format

Specify the E1 frame format to be used on this port. The choices are as follows:

Standard E1 frame format using the framing bits in time slot 0 for framing.

E1-CRC

E1 frame using framing bits in both time slot 0 and

CRC-4

multiframe for fram-

ing.

E1-MF

E1 frame using framing bits in both time slot 0 and time slot 16 multiframe for
framing.

E1-CRC-MF

E1 frame using framing bits in time slot 0, time slot 16 multiframe, and

CRC-4

multiframe for framing.

unframed

The framing software will not look for framing bits to determine the start of a
frame or multiframe. Data is treated as a data stream. When used in a circuit
emulation application, this option should be chosen when configuring an
“unstructured” circuit emulation service.

Important Note

You cannot use the unframed format on WAN
modules.

3) Not FAS

Indicates whether you want to add an extra level of frame checking. E1 frames in time slot 0
are composed of alternating bits of

FAS

(Frame containing Frame Alignment Signal) and

NFAS

(Frame not containing Frame Alignment Signal). The

Not FAS

option tells the framer to check

framing on

FAS

and

NFAS

bits. Normally, the framer checks only

FAS

bits, which contain the

frame alignment signal pattern. If you enable

Not FAS

, then framing software will additionally

also check

NFAS

bits, which include remote alarm indication information.

4) Line Build Out

The

port supports short haul or long haul interfaces. Only

ports equipped with a Line

Interface Unit (

LIU

) chip support long haul. Long haul support is necessary if this E1 port is

directly connected to a Central Office (i.e., not connected via an external CSU) and the cable
length is greater than 655 feet (200 meters). If this E1 port connects locally using less than 665
feet (200 meters) of cable, then short haul is adequate.

Note

All T1/E1 ports are equipped with a Line Interface Unit
(

LIU

) chip.

An additional prompt displays requesting the resistance type used for this port connection.

40) Cable Type

Indicate the cable resistance type used on the short or long haul interface. The cable resis-
tance type can be 75 ohm or 120 ohm. The resistance is a set via a jumper on the E1
board; it is not configurable through software.

5) Line Coding

The type of physical encoding used on the connection.

AMI

(Alternate Mark Inversion) is

more sensitive.

HDB3

(High Density Bipolar 3) should be used when possible.