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14.11 G.747 Basics
G.747 multiplexing is a mixture of T3 and E1. It is a two-step process of merging 21 E1 lines into a
single T3 line. First, three of the E1 lines are merged into a single T2 rate and then seven T2 rates are
merged to form the T3 just like the normal T2 to T3 multiplexing scheme. Once the three E1 lines have
been multiplexed together, the resultant 6.312Mbps data stream is treated just like a T2 data stream that
contains four T1 lines. We will only discuss the G.747 multiplexing scheme in this section. See Section
for details on the T2 to T3 multiplexing scheme (e.g., M23) and the T3 framing structure.
Table 14-6. G.747 Carrier Rates
T OR E
CARRIER
LEVEL
NOMINAL DATA
RATE (Mbps)
E1 2.048
T2 6.312
T3 44.736