Transcript Cisco Days Raleigh v2

IP Multicast for
Entertainment Video
Cisco Days – Raleigh, NC
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Agenda
 Video System Elements
 Edge Reliant System Design (Example Topology)
 Multicast Overview
 Multicast Design Metrics
 Managing IP Multicast (CMM & VOS)
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Video
System
Elements
 System Elements and Resiliency
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Video System Elements
Encoding
STB
Decoding
Digital
Content
QAM
Modulation
MPTS
Muxing
SPTS
Muxing
Encryption
Encryption
Transport
Network
Transport
Network
DPI Ad
Splicing
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Design Dependencies
The design efficiency of the entertainment network is largely dependent on the IP
Multicast capabilities of the components in the system. We should consider those
capabilities categorically:
 Video Sources (single or redundant)
Digital Simulcast (MPTS)
Switched Digital (SPTS)
DPI (Both MPEG-2 Transport Types)
 Edge Receivers (network intelligent or not)
QAM Modulators
Decoders
 Nodes and Links (functionality required is based on source/edge)
Transport Equipment
Routers and Interfaces
Forwarding Protocols
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Resiliency Options
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Single Video Source
Leveraging a single video source into a High-Availability design
requires some method of replication that may not establish
uniqueness of the video streams.
 Non-Optimal
Optical splitting will create duplicate traffic that uses the same multicast
addresses
Forced multicast forwarding into transport paths increases video flow
replication and transport demand
 Optimal
Sophisticated source devices that replicate video traffic as uniquely
addressable source streams
Intelligent Edge devices dynamically select video traffic to minimize
bandwidth and replication
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Secondary/Backup Video Source
 Layer-2 forwarding using VLAN’s with Any Source
Multicast (ASM), or classic multicast
 Layer-3 forwarding of adjacent system content using
ASM multicast IP addressing
 Layer-3 forwarding of adjacent system content using
Anycast multicast IP addressing
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Video Edge Considerations
 IGMP support (or the lack of it) is the largest factor
driving network design
 Non-IGMP compliant devices create design constraints
that impact bandwidth demand and network device
efficiencies
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Video Edge Dependency Ultimately
Drives Topology Decisions
An Evolving Distribution Network :
L2  IGMPv2/SSM Mapping  End-2-End IGMPv3/SSM
 Variations in consistency between Edge Gear products’ support of IGMP
vs Promiscuity constrain your design options
 Promiscuous devices have the ability to receive single source
duplication that uses identical IPmc addressing (like Anycast)
But - limits scalability in a VLAN (to 1 GE)
IGMP Snooping is required to protect video edge devices from
oversubscription
Requires VLAN isolation for promiscuous devices which factors up the
multicast replication at the edge router and the increases transport
bandwidth
 IGMP capable devices allow the total network to scale better
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Edge Reliant
Systems
 Migrating to Efficient IP Multicast Systems Design
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Distribution Options
 Layer-2 and Layer-3 networks have distinct scalability
differences
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Layer-2 Multicast Fundamentals
 Layer-2 Networks propagating Multicast in a
broadcast fashion
 Resiliency is achieved through explicit packet
duplication
 Video Edge equipment vendors have different
multicast capabilities today, which may impose a
“transport tax” in the form of multiple VLAN’s for
different applications
802.1q P2P links to create segregated traffic
One VLAN for each 1G of redundant traffic – approx. 240 channel
ceiling
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Single Source Example
Single Router, Single Ring/Link Transport
Source devices feed a unique multicast to a single router, using
“isolated” Layer-2 trunks for redundant distribution to remote locations
802.1q Trunk
SVI 10
Static-group
Output result is identical
multicast groups - edge must
support duplicate addressing
scheme.
Statistical
Multiplexers
(Works for promiscuous receivers.)
Static-group
SVI 20
802.1q Trunk
VLAN path terminates at the “last hop” in the ring so that no loop exists.
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Single Source Example
Dual Routers, Single Ring Transport
Source devices feed a unique multicast shared between two routers,
with redundant distribution to remote locations using “isolated” Layer2 trunks
SVI 10
802.1q Trunk
Static-group
Statistical
Multiplexers
Output result is identical
multicast groups - edge must
support duplicate addressing
scheme.
This link
supports
bridging of
all source
multicasts
(Works for promiscuous receivers.)
Static-group
SVI 20
802.1q Trunk
VLAN path terminates at the “last hop” in the ring so that no loop exists.
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Layer-3 IP Multicast Fundamentals
 Layer-3 networks propagate IP Multicast using
dynamic traffic selection
 Intra-Regional Backup and/or Redundancy of video
sources leverage the bandwidth efficiency of IP
Multicast
 Edge network segments have greater flexibility,
when supporting multi-vendor implementations
using Layer-3 addressing and forwarding
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Single Source Example
Dual Router, Single Ring Transport
Source devices feed a unique multicast propagated between two
routers using two separate OSPF routing instances. Remote routers
see both instances for resiliency.
OSPF 10
Static Groups
Statistical
Multiplexers
This link
supports
routing of
all source
multicasts
Output result is identical
multicast groups - edge must
support duplicate addressing
scheme.
(Works for promiscuous receivers.)
OSPF 20
Static Groups
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Dual Logical IPmc Topologies on Single
Network for High Availability Resiliency
 Can provide different subsets of the network for
different classes of traffic
 Can share links to reduce cost
 Can share nodes to reduce cost
 Vs. Virtual Routers or similar “virtual network”:
No need for subnet encapsulation for multiple topologies
 Vs. RSVP-TE P2MP
Easier DIffserv type approach (not fixed on per flow/tree)
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Dual Multicast Topologies for
HA Resiliency
STBs
HFC
Redundant
Encoder/Multiplexer
Redundant
Decoder / Ad-Inserter/..
 Send traffic twice to different multicast groups
(eg: green = 232.1.8.1, red = 232.1.8.2)
 Use logical path separation in network to pass red/green across different paths
Note: dual topologies just one solution
 Receivers receive both copies.
 No single network failure will cause any service interruption
 Same bandwidth allocation needed as in traditional SONET rings,
but solution even better: 0 loss instead of 50 msec.
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Dual Multicast Topologies for
High Availability Resiliency
Rcvr
Rcvr
IGP costs different in each
Topology
Rcvr
Rcvr
Redundant
Encoder/Multiplexer
Unicast traffic flows in
the opposite directions
Rcvr
Small metric
Rcvr
Large
metric
 Topology sharing of links:
Large
Small metric
 Particular useful in rings.
 Two topologies also useful for
unicast (eg: VoD load splitting)
 Requires unidirectionally “weighted” link metric to force opposing reachability
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Dual Source Example
Dual Router, Single Physical Transport
Multiple unique sources feed two routers which support two separate
OSPF forwarding instances. Remote routers see both instances for
resiliency.
OSPF 10
Static or IGMPvX
Primary Source
Output result is unique
multicast groups and unique
source IP addresses.
This link
supports
routing of
all source
multicasts
(Works for promiscuous receivers.)
OSPF 20
Static or IGMPvX
Backup Source
IGMPv3 and SSM function nicely in this design if supported by the Edge Device.
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Phased Resilient Network
Implementation Example
 Build the Foundation and Grow As Needed
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Edge Reliant Design – Phase 1
Leverage Logical Network Subsets
QAM
Library VoD
Propagation
Streaming VoD
Server
QAM
Simulcast
Source
QAM
RGB
Mux
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CATV
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Edge Reliant Design – Phase 2
Introduce Node Resiliency
QAM
Library VoD
Propagation
Streaming VoD
Server
QAM
Simulcast
Source
QAM
RGB
Mux
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CATV
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Edge Reliant Design – Phase 3
Introduce physical layer resiliancy
Library VoD
Propagation
Streaming VoD Server
QAM
CATV
Simulcast
Source
OSPF weighted low
QAM
Primary Simulcast
Secondary Simulcast
Primary VoD Prop
RGB
Mux
CATV
Secondary VoD Prop
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Edge Reliant – Phase 4
Introduce Non-stop Forwarding Network Nodes
7600
Simulcast Source B
Streaming VoD
Server
Library VoD Prop
QAM
CATV
CRS-1
Simulcast Source A
OSPF weighted low
QAM
Primary Simulcast
RGB
Secondary Simulcast
Mux
Primary VoD Prop
CATV
Secondary VoD Prop
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7609 Design Strengths
 Converged Services on redundant 7600’s
 Service Separation through dedicated interfaces, simplified operational
requirements
 Efficient distribution of multicast traffic via IP routing
 Deterministic traffic path based on known routing cost
 Multiple redundancy options available per service
 Predictable and manageable scaling per service
 Wide range of L2 & L3 VPN commercial services available
 Utilizes a best practice design and features widely deployed in the field
today (experience to draw upon.
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Dual-Homed Edge Devices
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Time Warner San Antonio – “DVT” (10GEx4)
HUB
6300
HUB
6200
HUB
6700
HUB
6600
HUB
5200
HUB
6400
HUB
6100
HUB
6800
HUB
6500
HUB
5100
HE/HUB
6000
HUB
5300
HUB
1400
HE/HUB
5000
HUB
1300
HUB 3000
HUB 1000
(THUB)
(THUB)
HUB
3100
HUB 2000
(THUB)
HUB
2200
HUB
2100
HUB
2500
HUB
2300
HUB
1100
HUB
1200
HUB
3400
HUB
2400
HUB
2300
HUB
2200
HSD
DVT
METROE
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C&C
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BMR1200
San Antonio – Hardware Installed
Real Time Encoders
Multicast
Sources
BroadBus
DFC Based
6704 links
at all THUB
Locations
BroadBus
Catalyst 4948
BMR1200
Ad, Splice
and
Clamping
7600
7600
7600
HE/HUB 6000
HE/HUB 5000
CFC Based Line
Cards for 10GE
and 1GE output to
Sub-Rings
7600
HUB 3000
(THUB)
7600
7600
7600
HUB 1000
(THUB)
HUB 2000 (THUB)
7600
7600
7600
Catalyst 4948
RGB1
HUB 2100
RGB2
GQAM
BME50
RF
Plant
Analog/ Digital RF
SuperTrunk to DHUBs
BME50
Catalyst 4948-GE
HUB 2300
HUB 2200
Simulcast / SDV GE Path
VOD 10GE Path
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10GEx4 Transport Links
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Multicast
Overview
 Highlighting the Fundamentals
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IP Multicast
Business Drivers
The Problem: Inefficient Multipoint Techniques
Multiple Unicasts
Broadcast
Raleigh
Raleigh
???
Columbia
Columbia
???
???
???
???
Three copies of the same
packet are transmitted
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The entire network receives
one packet even if there are only a
few receivers
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IP Multicast
Business Drivers
The Solution: Multicast
Multicast
Group
• Multicast Transmission: Source sends a single
multicast packet addressed to a multicast group number.
• Intelligent networking devices then dynamically build
efficient paths and deliver packets to all recipients who
have joined that multicast group.
•Introduces a new class of IP addresses:
Class D = 224.0.0.0 239.255.255.255
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IP Multicast
Business Drivers
Distribution Times
Point-to-point vs. Multicast
Point-to-Point Transfers at 512 kbps
Files Size
100 Servers
1000 Servers
5000 Servers
1 MB
25 Minutes
4.3 Hours
22 Hours
100 MB
43 Hours
434 Hours
2170 Hours
300 MB
130 Hours
1302 Hours
6510 Hours
Multicast Transfers at 512 kbps
Files Size
Presentation_ID
100 Servers
1000 Servers
5000 Servers
1 MB
16 Seconds
16 Seconds
16 Seconds
100 MB
26 Minutes
26 Minutes
26 Minutes
300 MB
78 Minutes
78 Minutes
78 Minutes
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Multicast
Design
Metrics
 Protocols That Are Critical For Success
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Key IP Multicast Protocols
 Protocol Independent Multicast (PIM)
Defines the method of propagation of multicast traffic
 Internet Group Management Protocol (IGMP)
Defines how receivers and sources establish and discontinue
membership relationships
 Internet Gateway Protocol (IGP)
Used by PIM to ensure that optimal paths are used to deliver
services, and prevent routing loops
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Step 1 – Enabling IPmc in the Network Node
 IP Multicast traffic support is not usually enabled by default on
most Layer-3 network devices.
 There are commands for global support on the router, and at the
interface level (or SVI) that:
Enable multicast traffic on the platform…
Configure the appropriate multicast routing protocols and multicast
client support settings based on the receiving devices downstream
from the node.
NOTE: Most applications require a configuration tuning to bring
performance and security in alignment with network policies.
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Step 2 – Multicast Routing Protocols
Protocol Independent Multicast (PIM)
 PIM is the industry standard family of routing protocols used to establish a logical
“domain” of IPmc peers
 Network Nodes become PIM peers when connected interfaces are configured with
a similar PIM protocol mode
 PIM peers share information about IPmc traffic sources, and direct traffic to active
receivers (IPmc requestors) according to the PIM mode
PIM operational modes are dense, sparse or sparse-dense
Dense mode floods (pushes) all IPmc traffic into domain interfaces until pruning stops the
flooding.
Sparse mode forwards (pulls) an IPmc group into domain interfaces only if requested.
 Sparse-mode requires devices called a “Rendezvous Point” to coordinate source
device awareness in the PIM domain
 The Layer-3 routing protocol (IGP) of the network is used to establish the path
which the IPmc traffic will take between the IPmc source and requestor
There is a potential for a non-synchronized condition where PIM tries to build a IPmc tree
through an ideal IGP path that may not be PIM enabled (uRPF). Be sure to enable your
shortest path for PIM
 NOTE: The mode you select is dependent on the default behavior you require for
your application and its resiliency requirements
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Step 2 (cont.) – Sparse vs. Dense Perspective
While browsing the CISCO-IPMROUTE-MIB.my file I
happened across a succinct description, that offered
another view when comparing sparse mode to dense
mode:
“In sparse-mode, packets are forwarded only out
interfaces that have been joined. In dense-mode,
they are forwarded out all interfaces that have not
been pruned."
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Step 3 – Internet Group Management Protocol
IGMP
“Joining” is the common term used to describe a host system that requests to become
a member of an IPmc group – it is said that the host will “join a group”
The membership request is dynamic when the host uses the IGMP protocol to make
the request
IGMPv1 and IGMPv2 are said to be non-source-specific requests as they only able to
request membership by the IPmc group identity - commonly called a (*,G) request,
or join
dense or sparse mode are commonly used
IGMPv3 specifies the exact source IP address and IPmc group address – commonly
called an (S,G) request, or join
Source Specific Multicast (SSM) implementations require IGMPv3 support on the requestor
or by proxy at the first hop router via SSM-Mapping
SSM uses sparse-dense mode only, and does not require rendezvous point configuration in
the PIM domain
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Protocol Independent Multicast
How Multicast Moves Over IP Networks
 Multicast Routing, IGMP Evolution, and the Impact on
Your Network
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What is PIM?
Protocol Independent Multicast (PIM):
 A Multicast routing protocol that define the rules used to
forward multicast traffic throughout the IP network.
 Network nodes (interfaces or links) are explicitly configured
as participants in PIM
 There are multiple PIM operating modes, each with specific
operational benefits
 PIM is dependent upon the underlying unicast routing
protocols for specific reachability.
 A multicast enabled network is commonly referred to as a
“PIM domain”.
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Classic Multicast
Any-Source Multicast (ASM)
ASM: Classic IP Multicast service (rfc1112, ~1990)
 Sources send IP multicast packets to a IP multicast group
 Receivers “join an IP multicast group”
 Network node will deliver packets sent by any source to an IP
multicast group to all receivers that have joined the IP
multicast group.
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ASM Multicast Routing Modes
Dense Mode (DM):
A traffic “push” mode that actively attempts to send
multicast data to all potential receivers in the PIM domain
(flooding), and relies upon their self-pruning (removal from
group) to achieve desired distribution.
Sparse Mode (SM) RFC 2362:
A traffic “pull” mode that relies upon an explicit joining
method (IGMP) before attempting to send multicast data to
requestors of a multicast group.
Source Specific Multicast:
A mode used where receivers have the ability to directly
request multicast groups from a specific source.
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SM Multicast Components
Rendezvous Point (RP):
The multicast router that is the root of the PIM-SM shared multicast distribution tree. This
router knows about all the multicast sources in the PIM domain.
Designated Router (DR):
The router in a PIM-SM tree that forwards Join/Prune messages upstream to the RP in
response to IGMP membership info it receives from IGMP hosts.
Shared Tree:
Efficiently built (temporary) distribution path from the central RP to all DRs who have
directly attached members of a particular multicast group. Ensures that there are no
unnecessary duplication of the multicast data within network, but may result in suboptimal routing between source and receivers.
Source Tree:
A multicast distribution path that directly connects the sources and receivers DRs (or the
RP) to obtain the shortest path through the network. Results in most efficient routing of
data between source and receivers, but may result in unnecessary data duplication
throughout network if built by anyone other then the RP.
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Multicast Domain
Multicast Routing: PIM-SM
Segment A
Segment B
RP
Multicast Source
X
DR
RP
Multicast Source
Y
ISP B
ISP A
DR
PIM-SM
DR
Protocol Independent Multicast
 Dense mode
 Sparse mode
-Uses “push” model
-Traffic flooded throughout network
-Pruned back where it is unwanted
-Flood-and-prune behavior (every 3
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-Uses “pull” model
-Traffic sent only to where it is requested
-Explicit join behavior
minutes)
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SSM and Anycast
 SSM: Source Specific Multicast (~2000)
Source(s) still send IP multicast to IP multicast group address – but refered to
as an “(S,G) channel”
Receivers subscribe to (S,G) channel by indicating to the network not only IP
multicast group it wants but also the specific source
Network will deliver packets on a per-channel basis only
 Anycast “Redundant IP address” for source-redundancy:
Primary target for SSM: “Single-Source” TV/Audio/Data ”broadcast”
applications
Using a single IP address on multiple sources for redundancy, the network
dynamically announces closest source via Unicast Routing.
But why SSM, is ASM not good enough or better ?
ASM is simpler to deploy – no RP’s or DR’s needed resulting in simpler
configurations
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Reasons To Use SSM
 Complexity of protocol operations required for SM
PIM-SM (Shared trees, shortest path trees, RPT/SPT switchover)/MSDP, RP
announcement (AutoRP/BSR), RP placement, RP redundancy
Operating PIM-SM over core networks complicated
Bandwidth reservation (RSVP, per group ? Per source ?),
Link/Node Protection with PIM-SM are all more complex
 Scalability, Speed of protocol operations (convergence)
Operations for both SPT and RPT needed – and their interaction
 DoS attacks by unwanted sources
Receivers can ignore packets, but network resources can only be protected by
extensive network source access control == network level application control.
 Address Allocation
Try to get “global scope” IPv4 multicast address (GLOB, …)
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IP Multicast Routing Summary
 SSM is a key enhancement to IP multicast
Better (manageable / scalable) multicast service delivery
 SSM may not replace ASM in all applications
Many-source applications
Source-discovery with IP multicast
 ASM and SSM can coexist
 Recent means of improvement / simplification of ASM
Easier protocols for ASM
Bidir-PIM (intradomain only today)
Easier RP-redundancy (PIM-Anycast-RP, Prioritycast)
IPv6 multicast (address allocation, embedded-RP)
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IGMP
Managing Multicast Propagation
 IGMP Evolution, and the Impact on Your Network
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IGMP Versions
• Version 1, specified in [RFC-1112], was the first widely-deployed
version and the first version to become an Internet Standard.
• Version 2, specified in [RFC-2236], added support for "low leave
latency", that is, a reduction in the time it takes for a multicast router
to learn that there are no longer any members of a particular group
present on an attached network.
• Version 3 adds support for "source filtering", that is, the ability for
a system to report interest in receiving packets *only* from specific
source addresses, or from *all but* specific source addresses, sent to
a particular multicast address.
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IGMP v1 - Behavior
router
IGMP routing update
IGMP routing update
30 sec
router
router
LAN 2
LAN 1
Group
member
Presentation_ID
IGMP
query
IGMP
report
Group
member
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IGMP
report
LAN 3
IGMP query
Group
member
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IGMP v1 - Pruning
router
router
router
router
router
Group
Member
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IGMP
query
Group
Member
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router
Group
Member
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IGMP v2 - enhancements
IGMP v2 introduces a procedure for the election of the router querier
for each LAN. In the version 1 this was done by different routing
policies.
Group-Specific Query – Added to permit queries form a router to a
specific group and not to all-host address in the subnet (224.0.0.1).
Leave-Group – for a reduction in the time it takes for a multicast
router to learn that there are no longer any members of a particular
group present on an attached network. Sent to all-routers (224.0.0.2)
When a router receives the Leave-Group message, it uses the GroupSpecific Query to verify if the sender was the last one in the group.
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IGMP v2 - Pruning
router
router
router
IGMP Leave
router
router
Group
Member
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Specific
IGMPGroup
Leave query
Group
Member
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router
Group
Member
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IGMP v3 - features
 MUST be interoperable with v1 and v2
 Source-filtering
Only from a source
All but a source
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IGMP v3 - The protocol
(for group members)
Action on Reception of a Query
Therefore, the system must be able to maintain the following state:
• A timer per interface for scheduling responses to General Queries.
• A per-group and interface timer for
scheduling responses to GroupSpecific and Group-and-SourceSpecific Queries.
router
IGMP
report
Wait for random interval
IGMP query
• A per-group and interface list of
sources to be reported in the
response to a Group-and-SourceSpecific Query.
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IGMP v3 - The protocol
(for multicast routers)
Conditions for IGMP Queries
• Periodic request for membership
Multicast routers send General Queries periodically to request group
membership information from an attached network.
These queries are used to build and refresh the group membership
state of systems on attached networks. Systems respond to these
queries by reporting their group membership state (and their desired
set of sources) with Current-State Group Records in IGMPv3
Membership Reports.
IGMP Request
router
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IP Multicast
Video Channel Relationships
 Channel Identities Change During Delivery
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IPmc Flow Relationships
 Video Transport Systems generally contain components that
manipulate source video streams for a number of reasons…
Statistical Multiplexing (building MPEG-2 MPTS’s)
Digital Program Insertion (ad-insertion)
Encryption or DRM
 IPmc group addressing will change as video programs flow from
their original sources through these components to consumers.
 Awareness of those flow relationships are critical for successful
service management.
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Geographic Relationships
Encoders
Mux-Demux
Ad Insertion
Encryption
QAM,
Decoder
Sources
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Transport
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62
Possible IPmc Flow Stages
Satellite
Receivers
Encoders
Multifunction
devices
Mux / Demux
Presentation_ID
Ad Insertion
Ad Insertion
Ad Insertion
Encryption
Encryption
Encryption
Edge QAM
Edge QAM
Edge QAM
Zone 1
Zone 2
Zone 3
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Control Multicasts (Out-Of-Band)
 Emergency Alert Service (EAS)
 BootLoaders (best way?)
 Conditional Management
 Hub-Specific Programming
 NAT’d Multicasts
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64
Video Program Path Changes Over Time
SD Source
HD Source
Mobile
DPI
DRM
P-Key
PC
Set Top
Program Migration
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Managing
IP Multicast
 Cisco Multicast Manager
 Video Operations Solution
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The issue
How do you proactively or reactively monitor or diagnose a
specific video service or video stream(s) given the following:

4 Different Video Service Types (TWC single market example)
Broadcast
Simulcast
VoD
Switched

Mapped into two different MPEG Multiplex Streams
MPTS
SPTS

Which map into two different IP address service paths
Unicast
Multicast

Which map across one of three different major GE network architectures
Resilient Rings
GE Optical Muxponded Backhaul
Transport network aggregates to 10G (aka muxponded), across
GE IP Switched Backhaul
IP Switch aggregates to 10G, backhauled across a 10G transport network)

Across massive geography (TWC nationwide example)
2 NOCs
7 RDCs
41 Head Ends
20 hubs average per Head End
850 Hubs

And are applied in massive scale (TWC example)
Broadcast (80 channels = <500Mb multicast *per hub* average)
Simulcast (80 channels = <500Mb multicast *per hub* average)
VoD (1-12 streams per channel = 5Gb unicast *per hub* average)
Switched (80 analog + 120 digital channels = 1.5G multicast *per hub* average)
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Case In Point
2 x 7609 2 x 7609 2 x 7609 2 x 7609 2 x 7609
2 x 7609 2 x 7609 2 x 7609 2 x 7609
2 x 7609 2 x 7609
2 x 7609
Simulcast, HSD,
CommSrv, & VoD
2 x 7609
2 x 7609
10GE Rings
(6 λ)
Simulcast, HSD, CommSrv,
2 x 7609
& VoD 10GE Rings
(7 λ)
2 x 7609
2 x 7609
2 x 7609
2 x 7609
Carrollton
2 x 7609
Simulcast, HSD, CommSrv, VoD*
10GE Rings
(10 λ)
(*VoD for Plano comes directly
from Dallas HE)
2 x 7609
Grapevine
2 x 7609
2 x 7609
2 x 7609 2 x 7609
7609
7609
Plano
7609
7609
2 x 7609
20
bp
G
30 G
bps
s
CORE RING
(14 λ)
3 x 7609
2 x 7609
Dallas HE
30 Gbps
Arlington
2 x 7609 2 x 7609
Internet
bps
20 G
Thornton
7609
7609
2 x 7609 2 x 7609
2 x 7609
7609
Simulcast, HSD, CommSrv,
& VoD 10GE Rings
(7 λ)
2 x 7609
7609
Simulcast, HSD,
CommSrv, & VoD
10GE Rings
(6 λ)
2 x 7609
Simulcast, HSD, CommSrv, 2 x 7609
& VoD 10GE Rings
(6 λ)
2 x 7609
2 x 7609
2 x 7609
HSD 10 GE Shared
Commercial 10 GE Shared
VoD 10 GE Rings
2 x 7609
2 x 7609
2 x 7609
2 x 7609
2 x 7609 2 x 7609
2 x 7609
2 x 7609
2 x 7609
2 x 7609
2 x 7609
2 x 7609
2 x 7609
Simulcast Ring-A
Simulcast Ring-B
Existing 7609 Router
7609 Edge Router
CRS-1 Core Router
Presentation_ID
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Network Impact on Quality
Network
Headend
Home
IP Packet
Jitter
IP Packet
Delay
Poor Video
Good Video
Dropped IP
Packets
blocky effect, locking effect, freeze
frame, frame skipping…
Problems Caused by:
IP packet jitter – rate overruns and underruns
Dropped IP packets
Presentation_ID
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Popular Perceptions
 The only thing an IP network can do to affect the quality of
IPTV is loss
The perceptual quality of the video is the same at the STB as it
is at the headend if there is no loss within the network.
 Cumulative IP jitter may impact video quality, depending on
the receiver buffer size, and it is a leading indicator of loss
 Network latency does not impact video quality per se,
although it can cause a shift in view time
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Media Delivery Index (MDI)
An indicator of cumulative jitter and packet loss
MDI = Delay Factor : Media Loss Rate
 Delay Factor (DF) = The amount of buffer required to
transport the jittered packets in the network without loss
per sample period
DF is proportional to the delay introduced in the system due to
the network buffering.
 Media Loss Rate (MLR) = The total media packets lost
per sample period.
Presentation_ID
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Media Delivery Index
An Example
 MDI Measurement
 MDI Measurement
Delay factor is Good
Delay factor is not good
Media Loss is Good
Media Loss is not good
For 3.5MB/s Expected delay
DF: 2.81
Expected DF was 2.81
Network
Presentation_ID
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Presentation_ID
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