N10-005 · Question #437
The phone company has provided a channelized T1 line. Which of the following should this line be connected to?
The correct answer is B. CSU/DSU. A T1 line from the phone company must be terminated at a CSU/DSU, which converts the telco signal into a format a router or other CPE device can use.
Question
The phone company has provided a channelized T1 line. Which of the following should this line be connected to?
Options
- ASwitch
- BCSU/DSU
- CIDF
- DMDF
How the community answered
(27 responses)- A4% (1)
- B93% (25)
- D4% (1)
Why each option
A T1 line from the phone company must be terminated at a CSU/DSU, which converts the telco signal into a format a router or other CPE device can use.
A switch is a LAN device that operates at Layer 2 and is not designed to terminate WAN circuits such as a T1.
A CSU/DSU (Channel Service Unit/Data Service Unit) is the demarcation device required to terminate a T1 circuit from the carrier. The CSU handles line conditioning and loopback testing toward the telco, while the DSU converts the T1 signal into a format the connected router or other equipment can process.
An IDF (Intermediate Distribution Frame) is a structured cabling distribution point for horizontal runs, not a WAN circuit termination device.
An MDF (Main Distribution Frame) is the central cabling hub of a building's network infrastructure, but it does not electronically terminate a T1 signal from a carrier.
Concept tested: T1 WAN circuit termination with CSU/DSU
Source: https://www.cisco.com/c/en/us/support/docs/wan/t1-e1/14608-12.html
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