Switched Digital Video Flashcards
CRAN
Converged Regional Area Network
The ____ takes the reconditioned video streams to move
from the Master Headend to each local Headend,
hubsite and OTN on the Comcast Network.
converged regional area network. CRAN
What are the limitations of SDV( switched digital video)
Must be received as CBR, Expensive to
implement with new hardware, Limited
Bandwidth.
What are the benefits of SDV(switched digital video)
Saves Bandwidth for more products and services,
will be able to compete with other rival
companies.
How many channels are currently available on the 750 MHz lineup?
116
What component receives the national
content?
CMC, Comcast Media Center.
How can our customers benefit from SDV(switched digital video)?
They will be able to enjoy more services from our network and access other products with more flexibility due to the saved bandwidth.
used for video compression/decompression processess
Video Codec
How Does MPEG Work?
The MPEG the picture is broken up into rectangular areas called macroblocks, each of which has its own motion vector.
list picture hierarchy
- Frame
- Slice
- Macroblock
- Block
MPEG includes what encoded pictures?
- I - Frames
- B - Frames
- P - Frames
What is CBR (constant Bit Rate)?
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.
What is VBR(variable bit rate)?
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.
How many MPEG packets can fit inside one Ethernet packet?
7
how many packets are in an Ethernet packet?
1500
The ____ takes the reconditioned video streams to move
from the Master Headend to each local Headend, hubsite and OTN on the Comcast Network.
converged regional area network. CRAN
Why is it critical that Comcast utilizes CBR when implementing SDV?
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.
Describe the importance of MPEG in the Comcast Network under SDV.
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.
256 QAM
8 bits per symbol * the symbol rate
(5.361 million symbols) = 42.88 Mbps of raw
data.
In a GOP, which frame type acts as the headers?
I Frame
In a GOP, which frame type can be encoded without prediction?
B Frames
In a GOP, which frame type can be coded with forward prediction?
P Frames
Used to borrow bits from the network number to identify hosts
Subnet Mask
Identifies endpoints sharing the same network.
Network number
Identifies a specific endpoint (Computer or Computer Network).
Host number
Public IP
Routable on the Internet. This type of IP address can be assigned to a router and manage several servers including Web, FTP, DNS, etc.
Private IP
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.
name the 3 types for IPv6 addresses
Unicast, Multicast, anycast
what is SNMP( Simple network management protocol)?
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.
What IP version is currently in use
today?
IPv6
What is the purpose of subnetting?
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.
re-encoder
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.
What would occur if the SDVSM(switched digital video session manager) was inactive?
No SDV sessions could be requested – Switched Digital channels would not be able to be viewed
What is the primary function of the ERM(edge resource manager)?
Managing bandwidth and program resources on Edge QAMs for join/leave multicasts.
What is stored in the mini-carousel?
Channel Information
What device does the Edge QAM communicate with for session setup requests?
ERM( edge resource manager)
