User manual

Wide Bank 28 DS3 - Release 2.4 July 2004 2-33
Product Description
Tests and Loopbacks
DS3 Payload Loopback
DS3 Payload Loopback returns the received DS3 signal from the transceiver through the framer
and back to the transceiver output, overriding the DS3 signal created internally by multiplexing
the low-speed signals.
Figure 2-15 DS3 Payload Loopback
DS3 Equipment Loopback
DS3 Equipment Loopback returns the signal received from the M1-3 framer back to the input
of the M1-3 framer, replacing the signal received from the DS3 line. This loopback is
performed by the DS3 framer and validates a full internal DS3 path through the Wide Bank.
This loopback is used to send PRBS test patterns back to the low-speed transceivers during the
Wide Bank self-test mode.
Figure 2-16 DS3 Equipment Loopback
Loopback
Relays
Trans-
ceiver
Selector
M13
Framer
Trans-
ceiver
Relays
LS Card HS Card
Toward DS3
DS1/E1 DS3
Send AIS
Toward DS1/E1
Send AIS
Relays
Trans-
ceiver
Selector
M13
Framer
Trans-
ceiver
Relays
LS Card HS Card
Toward DS3
DS1/E1 DS3
Loopback
Toward DS1/E1