HP ProCurve Secure 7000dl Series Basic Management And Configuration Manual page 202

Configuring E1 and T1 Interfaces
ProCurve Secure Router Modules
4-16
Although E1 interfaces, including those for the G.703 port, support two frame
formats, only one option is listed if you enter the following command from the
E1 interface configuration mode context:
ProCurve(config-e1 1/1)# framing ?
Only the crc4 option is listed.
By default, the frame format is E1. If your public carrier is using the E1 frame
format, you simply accept the default setting by not entering a framing
command.
However, if your public carrier is using the CRC4 frame format, enter:
Syntax: framing crc4
ProCurve(config-e1 1/1)# framing crc4
To return to the E1 frame format, enter:
ProCurve(config-e1 1/1)# no framing crc4
T1 Frame Formats. For T1-carrier lines, public carriers use one of two
frame formats:
D4
ESF
D4 framing aggregates 12 DS0 frames into a single superframe. The ESF
standard multiplexes 24 DS0 frames into an extended superframe.
The ESF format has essentially replaced the D4 framing standard because it
frees up bits that can be used to maintain the connection. Due to its popularity,
ESF is the default setting for T1 modules on the ProCurve Secure Router.
To configure the frame format, enter the following command from the T1
interface configuration mode context:
Syntax: framing [d4 | esf]
If you want to use the default frame format, ESF, you do not have to enter a
command. However, if you want to configure the T1 interface to use D4, enter:
ProCurve(config-t1 1/1)# framing d4