Switched Digital Video

Question 1

CRAN

Answer 1

Converged Regional Area Network

Question 2

The ____ takes the reconditioned video streams to move
from the Master Headend to each local Headend,
hubsite and OTN on the Comcast Network.

Answer 2

converged regional area network. CRAN

Question 3

What are the limitations of SDV( switched digital video)

Answer 3

Must be received as CBR, Expensive to
implement with new hardware, Limited
Bandwidth.

Question 4

What are the benefits of SDV(switched digital video)

Answer 4

Saves Bandwidth for more products and services,
will be able to compete with other rival
companies.

Question 5

How many channels are currently available on the 750 MHz lineup?

Answer 5

116

Question 6

What component receives the national

content?

Answer 6

CMC, Comcast Media Center.

Question 7

How can our customers benefit from SDV(switched digital video)?

Answer 7

They will be able to enjoy more services from our network and access other products with more flexibility due to the saved bandwidth.

Question 8

used for video compression/decompression processess

Answer 8

Video Codec

Question 9

How Does MPEG Work?

Answer 9

The MPEG the picture is broken up into rectangular areas called macroblocks, each of which has its own motion vector.

Question 10

list picture hierarchy

Answer 10

• Frame
• Slice
• Macroblock
• Block

Question 11

MPEG includes what encoded pictures?

Answer 11

• I - Frames
• B - Frames
• P - Frames

Question 12

What is CBR (constant Bit Rate)?

Answer 12

CBR or Constant bit rate encoding means that the rate at which the codec’s output should be constant. As we stated in the last module, it ensures a steady data flow.

Question 13

What is VBR(variable bit rate)?

Answer 13

VBR or Variable bit rate encoding means that the rate at which the codec’s output will vary its output data per time slot. This allows for a higher bit rate for more complex segments while less space will be allocated for the stream.

Question 14

How many MPEG packets can fit inside one Ethernet packet?

Answer 14

7

Question 15

how many packets are in an Ethernet packet?

Answer 15

1500

Question 16

The ____ takes the reconditioned video streams to move

from the Master Headend to each local Headend, hubsite and OTN on the Comcast Network.

Answer 16

converged regional area network. CRAN

Question 17

Why is it critical that Comcast utilizes CBR when implementing SDV?

Answer 17

The video feed must be constant so there isn’t a heavy load of traffic at any point, which would consume too much bandwidth, possibly making services unavailable for certain customers.

Question 18

Describe the importance of MPEG in the Comcast Network under SDV.

Answer 18

MPEG is what makes SDV possible. Its compression allows the video to be sent to customers while maximizing the throughput of the switched digital stream.

Question 19

256 QAM

Answer 19

8 bits per symbol * the symbol rate
(5.361 million symbols) = 42.88 Mbps of raw
data.

Question 20

In a GOP, which frame type acts as the headers?

Answer 20

I Frame

Question 21

In a GOP, which frame type can be encoded without prediction?

Answer 21

B Frames

Question 22

In a GOP, which frame type can be coded with forward prediction?

Answer 22

P Frames

Question 23

Used to borrow bits from the network number to identify hosts

Answer 23

Subnet Mask

Question 24

Identifies endpoints sharing the same network.

Answer 24

Network number

Question 25

Identifies a specific endpoint (Computer or Computer Network).

Answer 25

Host number

Question 26

Public IP

Answer 26

Routable on the Internet. This type of IP address can be assigned to a router and manage several servers including Web, FTP, DNS, etc.

Question 27

Private IP

Answer 27

Not routable on the Internet. This type of IP address is commonly granted by a DHCP Server and resides behind a firewall, protected from intruders on the Internet. A Private IP address allows a single location to take 1 Public IP address (or many) and create a secure network of hundreds or more devices. This process, known as
subnetting will be discussed later.

Question 28

name the 3 types for IPv6 addresses

Answer 28

Unicast, Multicast, anycast

Question 29

what is SNMP( Simple network management protocol)?

Answer 29

SNMP is an application protocol used to communicate management information between the network management stations and the “agents” in the network elements through virtual connections. SNMP manages network resources through a database called a Management Information Base (MIB). MIBs are composed of managed objects in a strict format, which define the
statistical values and parameters of an element’s operation. Each managed object has an Object Identifier (OID) to distinguish it from other objects.

Question 30

What IP version is currently in use

today?

Answer 30

IPv6

Question 31

What is the purpose of subnetting?

Answer 31

It allows a large network to be broken down into several smaller networks. Helps for organization of IP address blocks, and smaller companies can effectively use
addresses.

Question 32

re-encoder

Answer 32

takes content from several places, such as the IP Backbone and CRAN, and improves the video quality before sending it over to the Bulk Encryptor. The Re-encoder performs these tasks at a National, Regional and Local Video levels. The video feeds are received as MPTS and leave the headends via SPTS CBR.

Question 33

What would occur if the SDVSM(switched digital video session manager) was inactive?

Answer 33

No SDV sessions could be requested – Switched Digital channels would not be able to be viewed

Question 34

What is the primary function of the ERM(edge resource manager)?

Answer 34

Managing bandwidth and program resources on Edge QAMs for join/leave multicasts.

Question 35

What is stored in the mini-carousel?

Answer 35

Channel Information

Question 36

What device does the Edge QAM communicate with for session setup requests?

Answer 36

ERM( edge resource manager)