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Chapter 1. Introduction
Network Loopbacks
There are two types of network loopbacks; see Figure
•Line Loopback: loops all of the received data back toward the network. The transmitted data is the identical line code that was received, including any bipolar violations or framing errors.
•Payload Loopback: similar to Line loopback, except that the framing is extracted from the received data and then regenerated for the transmitted data.
TSU |
NI CSU |
DS1 |
Payload Loopback |
Line Loopback
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Interface
Figure 1-7. Network Loopback Tests
TSU User Manual |