Cisco IGX 8400 Series Installation And Configuration Manual page 19

Figure 3-8 Pass-Through and Standard (External) UVM T1 Cabling
A. External line
(transparent)
B. One pass-through line
External
Passing
(transparent)
UVM 1
C. Two pass-through lines
External
UVM
Passed-
External
through
Passing
UVM 1
Passed-
through
Passed-
through
UVM 2
Installing Voice Cards
UVM 2
External
Passing
(transparent)
UVM 3
Card Installation and Node Startup 3-19