Principles of Synchronous Digital Hierarchy

205Plesiochronous Digital Hierarchy

8.2.7 E2 Bit Rate and Bit Rate Adaptation of E1s

If we summarize the preceding discussion of four sets of the E2 frame, we

have the bit distribution as under (Figure 8.20).

Please note that the number of bits carrying data in each set is different.

Set I has 200 data bits, as compared with 208 of them in sets II and III and

204 data bits in set IV. However, this distribution is only for the purpose of

management, it has no consequence on transmission, as the entire E2 frame

travels as one frame down the transmission media. Hence, we can say that

there are a total of 820 data bits and 28 other bits (we may call ...