Frame Format - HP ProCurve 7000dl Series Basic Management And Configuration Manual

Configuring E1 and T1 Interfaces
ProCurve Secure Router Modules
N o t e
4-16
T1 Line Coding. T1-carrier lines use the following line coding schemes:
AMI
Bipolar 8-Zero Substitution (B8ZS)
Like HDB3, B8ZS was designed to overcome the deficiencies of AMI. To
prevent synchronization loss, B8ZS replaces a string of eight zeros with a
string that includes two logical ones of the same polarity as a timing mark.
Because B8ZS has become the standard line coding used on T1-carrier lines,
it is the default setting on the ProCurve Secure Router.
To configure line coding on a T1 interface, enter the following command from
the T1 interface configuration mode context:
Syntax: coding [ami | b8zs]
For example, to configure the T1 interface to use the ami option, enter:
ProCurve(config-t1 1/1)# coding ami
If you want to accept a default setting, it is not necessary to enter the
command. For an E1-carrier line, you can simply accept the default setting of
HDB3. For a T1-carrier line, you can simply accept the default setting of B8ZS.

Frame Format

You must configure the E1 or T1 interface to use the same frame format as
that used by the public carrier. Otherwise, the WAN connection cannot be
established.
E1-carrier lines and T1-carrier lines use different frame formats.
E1 Frame Formats. E1 interfaces on the ProCurve Secure Router support
two frame formats:
E1
Cyclic Redundancy Check 4 (CRC4)
In the E1 frame format, a channel (or timeslot) is called a TS, and the 32
channels are numbered TS0 to TS31. Two channels are used to establish and
maintain synchronization and signaling: specifically, TS0 is used for synchro-
nization, error detection, and alarms, and TS16 is used for signaling. The other
channels are used to transmit data.
CRC4 is based on the E1 frame format but includes additional error detection.
A checksum bit is included in all even frames of the 16-frame multiframe:
frames 0, 2, 4, 6, 8, 10, 12, and 14. A total of 8 checksum bits are used.