Troubleshooting High-Speed Data Service (186-42-4)

What would be the downstream throughput if two quadrature amplitude modulation (QAM) channels with a throughput of 38 megabits per second (Mbps) were bonded?

76 Mbps.

Which step in the troubleshooting process requires a discussion with the customer to gather more detail about the problem?

Step 1: Identify the problem.

What requirements were needed for PacketCable to deliver a quality and reliable telephone service over a Data Over Cable Service Interface Specification (DOCSIS) access network?

Quality of service (QoS) controls, enhanced security, and adaptive equalization in the upstream path.

Which Data over Cable Service Interface Specification (DOCSIS) layer is used by the cable modem termination system (CMTS) to differentiate between cable modems?

The DOCSIS Media Access Control (MAC) Layer.

The first version of the Data Over Cable Service Interface Specification (DOCSIS) was approved as an international standard by what organization?

The International Telecommunication Union (ITU).

What Internet protocol (IP) address modes can a Data Over Cable Service Interface Specification (DOCSIS) 3.0 and 3.1 modem be provisioned in?

IP version 4 (IPv4), IP version 6 (IPv6), alternate provisioning mode (APM), and dual-stack provisioning mode (DPM).

When using a digital signal analyzer to troubleshoot data throughput in the Data Over Cable Service Interface Specification (DOCSIS) network, what is the minimum modulation error ratio (MER) into the cable modem for a 256- quadrature amplitude modulation (QAM) carrier?

32 dB or greater.

In a Data Over Cable Service Interface Specification (DOCSIS) network, why is the data throughput over the return or upstream path typically less than the throughput of data over the forward or downstream path?

Compared to the downstream path, the narrower bandwidths and lower orders of modulation used to transport data over the return path cause the downstream and upstream data throughput to be unequal or asymmetrical.

What criteria does the Data Over Cable Service Interface Specification (DOCSIS) certification process ensure?

Compliance with the DOCSIS standard and interoperability between suppliers.

Where do Data Over Cable Service Interface Specification (DOCSIS) modems receive their configuration files, billing system messages, and access control messages from?

From the cable modem termination system (CMTS), which interfaces with the operations support system (OSS) and acts as a proxy or messenger that transfers messages and files between the modems and the respective servers.

How does Internet protocol (IP) multicast differ from IP broadcast?

IP multicast traffic is only sent to specific modem addresses on the network; IP broadcast traffic is sent to all modems on the network.

What layers of the Open Systems Interconnection (OSI) reference model are specific to cable networks and are present only between Data Over Cable Service Interface Specification (DOCSIS) modems and the cable modem termination system (CMTS)?

Layers 1 through 4 (Physical layer, Data Link Layer, Network Layer, and Transport Layer) are applied between the DOCSIS modem and CMTS.

What are two features that were added in Data Over Cable Service Interface Specification (DOCSIS) 3.1 to extend the viability of hybrid fiber/coax (HFC) networks into the next decade?

Orthogonal frequency division multiplexing (OFDM) and low-density parity-check (LDPC).

Which Open Systems Interconnection (OSI) reference model layers does the Media Access Control (MAC) Layer in the Data Over Cable Service Interface Specification (DOCSIS) overlap so that the media access control (MAC) can be used by the cable modem termination system (CMTS) to differentiate between cable modems?

The Physical and Data Link Layers.

What was introduced in Data Over Cable Service Interface Specification (DOCSIS) 3.0 to allow enough bandwidth for upstream carriers from previous DOCSIS versions?

The option to increase the top frequency of the upstream to 85 MHz.

When analyzing a problem, what can the technician learn by asking the customer to show or demonstrate the problem?

The symptoms of the problem can be viewed, and any unusual screens or customer entries can be identified.

What communications access technology does the first version of the Data Over Cable Service Interface Specification (DOCSIS 1.0) use to send data upstream over the network's radio frequency (RF) return path?

Time division multiple access (TDMA).