CBT Broadcast Networking & IP Systems 2 — Questions and Answers
Question 1: Which protocol is commonly used to manage multicast group membership in broadcast IP networks?
- IGMP (Internet Group Management Protocol) (Correct answer)
- OSPF (Open Shortest Path First)
- SNMP (Simple Network Management Protocol)
- DHCP (Dynamic Host Configuration Protocol)
Correct answer: IGMP (Internet Group Management Protocol)
IGMP is used by hosts and routers to manage multicast group memberships, allowing switches to direct multicast streams only to ports with interested receivers.
Question 2: In broadcast networking, what does the term 'hitless switching' refer to?
- Switching between video sources with no frame-rate change
- Seamlessly switching between redundant network paths with no perceptible interruption (Correct answer)
- Cutting audio without a pop or click
- Transitioning from analog to digital signal without downtime
Correct answer: Seamlessly switching between redundant network paths with no perceptible interruption
Hitless switching refers to automatically switching to a redundant network path or stream when the primary fails, with no perceptible interruption to the media flow.
Question 3: What is the recommended minimum network bandwidth for transporting a single 1080i/59.94 uncompressed video stream per SMPTE ST 2110-20?
- Approximately 1 Gbps
- Approximately 3 Gbps (Correct answer)
- Approximately 100 Mbps
- Approximately 10 Gbps
Correct answer: Approximately 3 Gbps
An uncompressed 1080i/59.94 video stream requires approximately 1.5 Gbps for video alone, and with audio and ancillary data the total approaches 3 Gbps, typically requiring 10GbE infrastructure.
Question 4: What is the role of a grandmaster clock in a SMPTE ST 2110 broadcast facility?
- It sets the frame rate for all cameras on set
- It provides the master PTP reference that all other devices synchronize to (Correct answer)
- It controls the switching schedule for video routers
- It manages IP address allocation across the network
Correct answer: It provides the master PTP reference that all other devices synchronize to
The grandmaster clock is the PTP master reference in the network; all other devices synchronize their internal clocks to it, ensuring consistent timing across the entire IP facility.
Question 5: Which standard defines the Virtual Local Area Network (VLAN) tagging commonly used to segment traffic in broadcast IP networks?
- IEEE 802.3
- IEEE 802.1Q (Correct answer)
- IEEE 1588
- SMPTE ST 2022
Correct answer: IEEE 802.1Q
IEEE 802.1Q defines VLAN tagging, which allows broadcast facilities to logically segment network traffic (e.g., separating video, audio, and control traffic) on shared physical infrastructure.
Question 6: SMPTE ST 2022-7 is used in broadcast IP networks primarily for what purpose?
- Compressing MPEG-2 transport streams for IP delivery
- Providing seamless protection switching for redundant RTP streams (Correct answer)
- Encrypting media streams with AES-128
- Defining the audio sample rate for IP transport
Correct answer: Providing seamless protection switching for redundant RTP streams
SMPTE ST 2022-7 defines seamless protection switching (SPS), allowing a receiver to reconstruct a perfect stream from two redundant RTP streams even if one has packet loss.
Question 7: In a broadcast IP environment, what is the primary function of a Network Interface Card (NIC) with hardware timestamping support?
- To increase the NIC's data throughput capacity
- To generate accurate PTP timestamps for precise clock synchronization (Correct answer)
- To encrypt outgoing media streams at the hardware level
- To compress video before it enters the network
Correct answer: To generate accurate PTP timestamps for precise clock synchronization
Hardware timestamping on NICs enables highly accurate PTP (IEEE 1588) synchronization by timestamping packets in hardware rather than software, reducing jitter and improving timing precision.
CBT Broadcast Networking & IP Systems 2
Which protocol is commonly used to manage multicast group membership in broadcast IP networks?