Multicast Rutorial r3

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Transcript Multicast Rutorial r3

iMPath
Networks
Multicast Solution
How does it work ?
Digital Video Solution for Multiple Viewers
July 2005 version 3
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Note to Viewer
iMPath
Networks
• The content of this tutorial provides an overview of IGMP used in
Digital Multicast networks to familiarize customers with the
technology.
• The information in this document is subject to change without notifice.
• While every precaution was taken in the preparation of this document,
iMPath assumes no responsibility for errors or omissions. Neither is
any liability assumed for damages resulting from the use of the
information contained herein.
• Should you have any questions, please feel free to contact:
Daniel Brisson
Sr. System Engineer
iMPath Networks Inc
Tel: 613-226-4000 x 297
Email: [email protected]
Gilles Lebel
Sr. System Engineer
iMPath Networks Inc
Tel: 613-226-4000 x 224
Email: [email protected]
Typical Network Requirements
Backbone
Monitor any video from
anywhere in the network
iMPath
Networks
Multicast
iMPath
Networks
•
Multicast. Allows sending one copy of each packet to the group of computers
that want to receive it. Multicast can be implemented at the Ethernet linklayer or at the network layer (layer 3 of the OSI model). Computers join and
leave multicast groups by using the IGMP (Internet Group Management
Protocol) Each host can register itself as a member of selected multicast
groups through use of the Internet Group Management Protocol (IGMP).
•
Multicast is commonly used in audio and video streaming applications.
– It allows a single source of traffic to be viewed by multiple destinations
simultaneously.
– It is designed to provide an efficient transmission using the least amount
of bandwidth on the network to save cost.
IGMP is a standard IP protocol supported by most LAN/WAN vendors in
traditional LAN products, ATM, and gigabit Ethernet solutions.
•
Typical Network Components
L3 Switch/Router
L3 Switch/Router
Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet...
L3 Switch/Router
L3 Switch/Router
100 Meg
L2 Switch
L2 Switch
Networks
Typical high speed backbone
network consisting of Layer 2
or Layer 3 Ethernet Switches.
L3 Switch/Router
L3 Switch/Router
100 Meg
100 Meg
High Speed Switches are located at major
hub locations to collect or drop off data
traffic from this distribution
center.
L2 Switch
L2 Switch
Encoder
iMPath
L2 Switch
Encoder
Decoder
Decoder
Decoder
Decoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
Field hub locations are distributed where
the end devices are located.
They are
Decoder
used to collect and distribute traffic for
DecoderMessage
Cameras, Traffic Controllers,
Signs and many more.
Decoder
Decoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
•Controls camera PTZ
L2 Switch
Encoder
Several topologies can be used such as
Star and Linear
topologies being the most
Virtual Matrix Control Console
common.
•Displays
video to monitors
Virtual Matrix Control Console
•Displays video to monitors
•Controls camera PTZ
Encoder
Typical field encoder collector network
Control Center # 1
Control Center # 2
Typical Network Components
L3 Switch/Router
L3 Switch/Router
Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet...
L3 Switch/Router
L3 Switch/Router
100 Meg
The Control Centers provide
L2 Switch
L2 Switch
video viewing
and control of
Encoder
Encoder
the Camera PTZ, Traffic
Controllers,
or Message signs to
L2 Switch
L2 Switch
Encoder
Encoder
name just
a few.
L2 Switch
L2 Switch
Encoder
L2 Switch
iMPath
Networks
Multiple Control Centers may
be deployed with this
architecture.
L3 Switch/Router
L3 Switch/Router
100 Meg
100 Meg
L2 Switch
L2 Switch
Decoder
Decoder
Decoder
Decoder
Decoder
Decoder
Decoder
Decoder
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
The Virtual
Matrix is
commonly used in digital video
L2 Switch
networks providing
video
Encoder
display and control and to
L2 Switch
operate
complementary
Encoder
integrated applications.
L2 Switch
Encoder
Virtual Matrix Control Console
Virtual Matrix Control Console
•Displays video to monitors
•Controls camera PTZ
•Displays video to monitors
•Controls camera PTZ
Encoder
Typical field encoder collector network
Control Center # 1
Control Center # 2
iMPath
Why use IGMP?
Networks
Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet...
100 Meg
L2 Switch
100 Meg
L2 Switch
Encoder
L2 Switch
L2 Switch
100 Meg
L2 Switch
Encoder
Decoder
Decoder
Decoder
Decoder
Decoder
Decoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
Without IGMP support, multicast traffic is
transmitted to all the ports in each
network switch.
Decoder
Decoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
This unnecessary traffic floods the interfaces and
can quickly bog down the entire network.
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
Virtual Matrix Control Console
Virtual Matrix Control Console
•Displays video to monitors
•Controls camera PTZ
•Displays video to monitors
•Controls camera PTZ
Encoder
Typical field encoder collector network
Control Center # 1
Control Center # 2
iMPath
Why use IGMP?
Networks
For example:
With 25 cameras deployed,
Digital Backbone;
ATM, SONET,
Gigabit Ethernet...
each transmitting
at 5 LAN,
Mbps,
you will have over 125 Mbps of
combined traffic on your network
100Base-T
L2 Switch
100Base-T
L2 Switch
Encoder
L2 Switch
125 Mbps of traffic on each
100Base-X interface !!!!!!
100Base-T
L2 Switch
L2 Switch
Encoder
Decoder
Decoder
Decoder
Decoder
Decoder
Decoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
Encoder
125 Mbps of
traffic
Decoder
L2 Switch
L2 Switch
Encoder
L2 Switch
Decoder
Encoder
L2 Switch
Encoder
125 Mbps
of
traffic
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
Virtual Matrix Control Console
Virtual Matrix Control Console
•Displays video to monitors
•Controls camera PTZ
•Displays video to monitors
•Controls camera PTZ
Encoder
Typical field encoder collector network
Control Center # 1
Control Center # 2
iMPath
Why use IGMP?
Networks
For example:
With 25 cameras deployed,
Digital Backbone;
ATM, SONET,
Gigabit Ethernet...
each transmitting
at 5 LAN,
Mbps,
you will have over 125 Mbps of traffic
on your network
100Base-T
L2 Switch
Encoder
L2 Switch
100Base-T
Switch
On a 100L2Mbps
interface (optics or electrical) you
Encoder
cannot pass more then 100 Mbps of traffic.
L2 Switch
100Base-T
L2 Switch
Decoder
Decoder
Decoder
Decoder
Decoder
Decoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
In fact
a typical recommendation in the
L2 Switch
Encoder
industry is not
to exceed 70% of the bandwidth
in any segment.
L2 Switch
Encoder
L2 Switch
Encoder
PROBLEM
Combined 125 Mbps of traffic
on these interfaces.
Decoder
Decoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
•Controls camera PTZ
L2 Switch
Encoder
The capacity of this network is
Virtual Matrix Control Console
with only
25
cameras
•Displays video toexceeded
monitors
•Displays
video
to monitors
Virtual Matrix Control Console
•Controls camera PTZ
Encoder
Typical field encoder collector network
Control Center # 1
Control Center # 2
iMPath
Traffic flow with IGMP
Networks
Only 15 Mbps of multicast
traffic flows on this link
Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet...
100Base-T
100 Meg
100Base-T
Video Stream 3
Video Stream 1
L2 Switch
L2 Switch
Encoder
L2 Switch
L2 Switch
L2 Switch
Encoder
Decoder
Decoder
Decoder
Decoder
Decoder
Decoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Video Stream 2
Encoder
Encoder
Only 5 Mbps of
Multicast traffic
Flows on this
port
Decoder
Decoder
Video Stream 3
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Virtual Matrix Control Console
Virtual Matrix Control Console
•Displays video to monitors
•Controls camera PTZ
•Displays video to monitors
•Controls camera PTZ
Traffic is only present on the backbone when a
requests the Control
specific
encoder
stream
Typical field encoder collector decoder
network
Center
#1
Encoder
Encoder
Control Center # 2
iMPath
How does it work?
L3 Switch/Router
Networks
L3 Switch/Router
Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet...
L3 Switch/Router
L3 Switch/Router
L3 Switch/Router
L3 Switch/Router
100 Meg
Encoder
The Routers build and share a
table of all the “IGMP servers”
available on the network. They
keep a table of all the available
Multicast Addresses
This Router will not forward
any of the multicast traffic
until it receives a request
from a decoder (client)
Decoder
The Encoder is considered a
“server” in the IGMP world. It
generates a video signal that will
be made available to any
Decoder (client) on the network.
The Encoder transmits a signal with
a distinct destination address.
Between 224.x.x.x to 239.x.x.x.
(some addresses are reserved for
specific applications)
Typical field encoder collector network
Virtual Matrix Control Console
•Displays video to monitors
•Controls camera PTZ
Control Center # 1
Here is how it works -
iMPath
Networks
Joining a Group
L3 Switch/Router
L3 Switch/Router
Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet...
L3 Switch/Router
L3 Switch/Router
L3 Switch/Router
L3 Switch/Router
100 Meg
4
The Router responds and forwards the traffic to this
specific port on the Ethernet switch.
3
The Decoder registers this address in its table and
forwards the request (join the multicast group) to the
network
2
The Virtual Matrix application forwards a message to
the decoder to view a specific video stream. (request
to see video from address 224.168.32.55)
Encoder
224.168.32.55
Decoder
Virtual Matrix Control Console
•Displays video to monitors
•Controls camera PTZ
Typical field encoder collector network
1
The operator makes a request to see
a video on a specific monitor
Control Center # 1
Here is how it works -
iMPath
Networks
Leaving a Group
L3 Switch/Router
L3 Switch/Router
Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet...
L3 Switch/Router
L3 Switch/Router
L3 Switch/Router
L3 Switch/Router
100 Meg
Encoder
224.168.32.107
Video B
4
The Router stops video stream A, adds the new video
B to the group, and releases the traffic for video B to
this specific port on the Ethernet switch.
3
The Decoder un-registers from the present viewing
address (a “leave” message is sent) followed by
a “join” message which is sent with the new multicast
stream.
2
… the Virtual Matrix application ONLY forwards a
single message to the decoder to view video B stream.
(request to see video from address 224.168.32.107)
Encoder
224.168.32.55
Video A
Decoder
Virtual Matrix Control Console
•Displays video to monitors
•Controls camera PTZ
Typical field encoder collector network
1
When the operator makes a request
to change the view from video A to
video B…
Control Center # 1
Choosing your network elements
iMPath
Networks
• There are several types of digital network technologies to choose
from.
– SONET and ATM are still applicable but are now rarely
deployed on new installations.
– Ethernet is the most common technology due to the wide
range of affordable products available from many
manufacturers and the familiarity with Ethernet and IP
technology.
– The components more commonly used to build Ethernet
networks are Ethernet Switches.
– A high capacity Ethernet network is often referred to as the
“backbone” network.
Choosing your network switches
iMPath
Networks
• Choosing Ethernet Switches for your backbone network could
depend on several factors…
– Your specific port density requirements
– Network topology
– Temperature hardened requirements (outdoor)
– Support for IGMP protocol
– Your preferred manufacturer
– Specific product functionality
• This tutorial will explore a few topologies and the IGMP
functionality of different Ethernet Switches.
Ethernet Switch selection
iMPath
Networks
• There are 3 types of Ethernet Switches
– Layer 2 Switch
• Distributes traffic to each destination using MAC addressing table.
• Broadcasts the Multicast traffic across all its ports
– There are no Multicast traffic filters with these switches
– Layer 2 Switch with IGMP Snooping
• Distributes traffic to each destination using MAC addressing table
• Provides limited control of Multicast traffic to prevent broadcast of the
traffic to all ports.
• Layer 3 IGMP master is needed in the network
– Layer 3 Switch/Router with IGMP
• Distributes traffic to each destination using MAC addressing table.
• Distributes traffic to each destination using IP subnet addressing table.
• Provides maximum control of Multicast traffic to prevent broadcast of
the traffic to all ports and all subnet.
Layer 2 Switch
iMPath
Networks
Functionality
The combined Multicast Traffic is sent to all ports in each Switch
Combined 20 Mbps Multicast Video Traffic
20 Mbps
L2 Switch
L2 Switch
Encoder
Encoder
Encoder
Encoder
Decoder
5 Mbps Multicast Video per Encoder
This is a valid network topology for small networks
Ensure no more then 70% of the bandwidth of the lowest negotiated Ethernet
port speed is used. Not to be used with 10 Meg Half Duplex devices.
20 Mbps
0 Mbps
20 Mbps
0 Mbps
15 Mbps
5 Mbps
15 Mbps
5 Mbps
15 Mbps
5 Mbps
15 Mbps
5 Mbps
Bandwidth Restriction applies.
Decoder
Layer 3 Switch/Router with IGMP iMPath
Networks
Functionality
Multicast traffic is filtered out at each switch
Only the required traffic is transmitted on the network
Combined 10 Mbps Multicast Video Traffic
10 Mbps
L3 Switch
L3 Switch
Encoder
Encoder
Encoder
Encoder
Decoder
This is a valid network topology for any network - No topology restrictions
5 Meg
5 Mbps
0 Mbps
5 Meg
5 Mbps
0 Mbps
0 Mbps
5 Meg
5 Mbps
0 Mbps
5 Meg
5 Mbps
0 Mbps
5 Meg
5 Mbps
0 Mbps
5 Mbps
Deploying a Layer 3 at each collector HUB could be expensive
Decoder
Layer 2 & 3 Switch
iMPath
Networks
Typical Topology
0 Mbps
35 Mbps Combined Multicast Video
35 Mbps Combined Multicast Video
L3 Switch
L2 Switch
Encoder
L2 Switch
L2 Switch
5 Mbps
0 Mbps
0 Mbps
L2 Switch
L2 Switch
5 Mbps
Encoder
Encoder
Encoder
Encoder
The L3 Switch controls all
Multicast traffic.
L2 Switch
L2 Switch
Encoder
Encoder
L2 Switch
L2 Switch
Encoder
Encoder
L2 Switch
L2 Switch
Encoder
Encoder
In and out.
Decoder
Decoder
It eliminates transmitting
the combined multicast
traffic unnecessarily to each
port.
L2 Switch
L2 Switch
Encoder
Encoder
L2 Switch
Encoder
The use of L2 Switch in this topology is very common. Multicast traffic is repeated on all ports of the
switch within the segment but traffic from other segments is not seen. Traffic between the segments is
controlled by the L3 switch. Economical and practical solution that is very easy to deploy.
Layer 2 & 3 Switch
iMPath
Typical Topology – Industry concern
Networks
35 Mbps
0 Mbps
L2 Switch
L3 Switch
35 Mbps
Encoder
L2 Switch
L2 Switch
5 Meg
0 Meg
0 Meg
L2 Switch
L2 Switch
5 Meg
Encoder
Encoder
Encoder
Encoder
This solution
is very effective and greatly simplifies Network Management.
L2 Switch
Decoder
Decoder
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
However,
it is sometimes necessary to filter IGMP traffic at the edge.
L2 Switch
Encoder
Such solutions
were previously overlooked for economical reasons.
L2 Switch
L2 Switch
Encoder
Encoder
L2 Switch
L2 Switch
Encoder
Encoder
L2 Switch
An economical solution now exist: L2 switch with IGMP Snooping
Encoder
Overview of OSI Model
$
Application
Layer 7.
Presentation
Layer 6
Session
Layer 5
Transport
Layer 4
Network
iMPath
Networks
Traditionally performed by Routers
Layer 3- This layer defines the addressing and routing structure of the
Inter-network
This layer controls the Multicast traffic on the network.
Performed by Switches
$
Data Link
Physical
Layer 2- This layer defines the framing, addressing and error control of
Ethernet packets. Port addressing uses MAC address of each
device.
This layer effectively treats Multicast traffic as broadcast
traffic.
Layer 1
Overview of OSI Model
$
Network
iMPath
Networks
Layer 3- This layer defines the addressing and routing structure of the
Inter-network
This layer controls the Multicast traffic on the network.
This product can be used instead of expensive Routers
$
Layer 2 with IGMP Snooping- Layer 2 Switches with IGMP Snooping
functionality are now available. Provide all the functionality of a
Layer 2 switch with PARTIAL IGMP support.
This layer provides some Multicast traffic control on the
network.
New product introduced
Available with different port densities.
100Base-Fx to Gigabit trunks.
Temperature Hardened
Wide choice of manufacturers and products.
$
Data Link
Layer 2- This layer defines the framing, addressing and error control of
Ethernet packets. Port addressing uses MAC address of each
device.
This layer effectively treats Multicast traffic as broadcast
traffic.
Layer 2 Switch with IGMP Snooping
iMPath
Functionality
Networks
Local traffic is filtered out at each switch. Eliminates
multicasts traffic to all the ports
All the multicast traffic is sent to the central site. The L3
switch still controls the IGMP table of the network.
20 Mbps Combined Multicast Video
Encoder
Encoder
Encoder
Encoder
Valid network topology for any network
No topology restrictions
Decoder
5 Mbps
0 Mbps
5 Mbps
0 Mbps
0 Mbps
L3 Switch
5 Mbps
0 Mbps
5 Mbps
0 Mbps
5 Mbps
0 Mbps
5 Mbps
L2 with IGMP Snooping
Decoder
L2 with Snooping & L3 Switch
iMPath
Networks
Typical Topology
35 Mbps
L3 Switch
35 Mbps
L2 Switch
Encoder
Bandwidth Restriction applies. No more “70% of link capacity”
L2 Switch
5 Mbps
0 Mbps
L2 Switch
L2 Switch
0 Mbps
Encoder
Encoder
5 Mbps
L2 Switch
Encoder
Encoder
L2 Switch
L2 Switch
Encoder
Encoder
L2 Switch
L2 Switch
Encoder
Encoder
These links contain the
combined Multicast traffic
from all the Encoders in
their segment i.e. 35 Mbps.
Decoder
L2 Switch
L2 Switch
Encoder
Encoder
L2 Switch
L2 Switch
Encoder
Encoder
Switches with IGMP Snooping
eliminate flooding local interfaces
with Multicast traffic.
L2 Switch
Encoder
Very practical implementation
Management of the Ethernet Switches is required.
Decoder
How does it work?
iMPath
Networks
From the Encoder to the L3 Switch
L3 Switch
0 Mbps
35 Mbps
L2 Switch
L2 Switch
5 Mbps
Encoder
0 Mbps
The L2 Switch with IGMP
Snooping detects the
Query message from the
L3 Switch and logs
internally the ports that
pass traffic to the L3
Switch
Encoder
L2 Switch
Decoder
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
L2 Switch eliminates
flooding of the local
interfaces and passes the
Multicast traffic to the L3
Switch for processing.
Encoder
The L2 Switch
detects/identifies the
Multicast stream source
and logs internally what
port this stream came
from.
L2 Switch
Encoder
Each Encoder forwards a
constant Multicast stream
to the Ethernet Switch
(224-239.x.x.x)
The L3 Switch forwards
the IGMP Query on all its
ports to determine if there
are any devices that wish
to subscribe to a Multicast
Group.
How does it work?
iMPath
Networks
From the Encoder to the L3 Switch
At this point, the Multicast
traffic from all Encoders is
combined on this link
towards the L3 Switch.
35 Mbps Combined Multicast Traffic
L3 Switch
0 Mbps
L2 Switch
L2 Switch
Encoder
5 Mbps
0 Mbps
Encoder
L2 Switch
Encoder
Decoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
The L3 Switch detects the
Multicast traffic arriving on this
interface and logs internally all the
Multicast address for distribution.
How does it work?
iMPath
Networks
From the L3 Switch to the Decoder
L3 Switch
0 Meg
35 Mbps Combined Multicast Traffic
L2 Switch
L2 Switch
Encoder
The L3 Switch responds and releases the traffic to this
specific port on the Ethernet switch.
L2 Switch
Decoder
Encoder
L2 Switch
Encoder
L2 Switch
5 Mbps
0 Mbps
Encoder
The Decoder registers this address in its table and
forwards the request (“join” the multicast group) to
the network
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
The Virtual Matrix application forwards a
message to the decoder to view a specific
video stream on a specific monitor. (request
to see video from address 224.168.32.55)
The operator makes a request to see
a video on a specific monitor
Virtual Matrix Control Console
•Displays video to monitors
•Controls camera PTZ
Control Center # 1
How does it work?
iMPath
Networks
From the L3 Switch to the Decoder
0 Meg
The L3 Switch responds by forwarding
the stream
35 Mbps
224.168.32.140
L3 Switch
L2 Switch
Encoder
The L3 Switch responds by stopping the stream
224.168.32.55
L2 Switch
Decoder
Encoder
L2 Switch
Encoder
5 Mbps
L2 Switch
0 Mbps
Encoder
The Decoder sends an IGMP
request to join
(224.168.32.140)
The Decoder sends an IGMP “leave” message.
No longer need to receive the Multicast steam
(224.168.32.55)
L2 Switch
Encoder
L2 Switch
Encoder
The Decoder registers this address in its table and
forwards two messages to the switch
L2 Switch
Virtual Matrix Control Console
Encoder
The Virtual Matrix application forwards a message to the
decoder to view a specific video stream.
(224.168.32.140)
•Displays video to monitors
•Controls camera PTZ
The operator makes a NEW request
to see a video
onCenter
a specific
Control
# 1 monitor
How does it work?
iMPath
Networks
Typical Star Topology
Multicast traffic flows
from all Encoders to the
L3 Switch
L3 Switch controls the distribution of all Multicast
traffic to Decoders
L3 Switch
Decoders
Encoder
L2 Switch with
IGMP Snooping
Watch for…
iMPath
Networks
Limitations of IGMP Snooping
If this is a Gig E link and you have
more then 70 Meg of Video traffic, no
other application will run on this
network until the link is re-established.
L3 Switch
Maximum port traffic will be exceeded.
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
In the event of a communication
break between the L2 and L3
switches, the L2 IGMP Snooping
switch will behave like a L2 switchDecoder
L2 Switch
A few minutes after loss of signal, the
switches may* flood all Multicast signals
to the ports of every switch
Encoder
L2 Switch
Encoder
* Behavior may differ depending on switch manufacturer.
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switches with IGMP Snooping have limitations.
Watch for…
iMPath
Networks
Distributed Control Centers
This switch will allow traffic from
network A to flow to the Decoder when a
“join” request is received.
Multicast traffic flows to the L3 Switch
L2 Snooping
L2 Snooping
L3 Switch
Network
A
Encoder
Encoder
Video Source A
Decoder
Decoder
Decoder
Decoder
Multicast “join”
request sent to the L3
Switch
Control Center # 2
Control Center # 1
Watch for…
iMPath
Networks
Distributed Control Centers
It will not be possible to view
any video. Not even local video.
This switch requires connectivity to the
L3 switch to provide local “join”
L2 Snooping
Communication break
L2 Snooping
L3 Switch
Network
A
Encoder
Encoder
Decoder
Decoder
Decoder
Decoder
Video Source A
This limitation can be eliminated by installing an L3 Switch at all Control Centers.
Control Center # 2
Control Center # 1
Watch for…
iMPath
Networks
Distributed Control Centers
to the
L3 Switch
All Multicast traffic flows
will flow
to the
L3 Switch
L2 Snooping
L2 Snooping
L3 Switch
L2 Snooping
This switch will only forward traffic
from video source B when the
Decoder requests to join a video from
source B
Encoder
Encoder
Decoder
Decoder
Decoder
Decoder
Encoder
Video Source A
Encoder
Video Source B
Multicast “join” requests are sent to the L3
Switch
Control Center # 2
Control Center # 1
Configuration Tips
iMPath
Networks
L2 Switch with IGMP Snooping
This switch generates IGMP
Queries. It is considered as the
“Master” or the “Active” device
Two IGMP configuration modes can be
set in the switches.
Passive
L2 Snooping
Encoder
Encoder
Passive
L2 Snooping
Decoder
Decoder
Passive
L3 Switch
Decoder
Decoder
In this topology, there can only be one Master unit.
Control Center # 2
Control Center # 1
L2 Snooping
Encoder
Encoder
Configuration Tips
iMPath
Networks
L2 Switch with IGMP Snooping
Some L2 Switches with IGMP Snooping can be
configured as Passive or Active
Passive
L2 Snooping
This switch generates IGMP
Queries. It is considered as the
“Master” or the “Active”
device
Passive
L2 Snooping
Passive
L2 Snooping
L2 Snooping
In this topology, there can only
be one Master unit.
Encoder
Encoder
Decoder
Decoder
Decoder
Decoder
Encoder
Encoder
This topology should only be considered for small networks.
Most L2 IGMP Snooping Switches do not have the capacity to handle
a large
table# 2of IGMP Control
Multicast
Control Center
Center #traffic.
1
Multi-Vendor Support
iMPath
Avoid…Mixing IGMP Snooping Switches
Passive
L2 Snooping
Passive
L2 Snooping
Manufacturer A
Encoder
Encoder
Active
L2 Snooping
Manufacturer A
Decoder
Decoder
Control Center # 2
Networks
Passive
L2 Snooping
Manufacturer B
Decoder
Decoder
Manufacturer B
Encoder
Encoder
Control Center # 1
Although some L2 IGMP Snooping Switch manufacturers may imply that
they can integrate into a multi-vendor solution, this is not recommended since
IGMP Snooping is not an RFC standard. Implementation differs between
manufacturers. (Proven to fail in our labs)
Multi-Vendor Support
iMPath
Recommendation …
Use L2 with IGMP
Snooping
“Hardened” products
are available
Networks
L3 Switch
L2 Switch
Encoder
L2 Switch
Encoder
Keep it simple.
A single manufacturer
solution is recommended
Decoder
L2 Switch
High end products should be used
for L3 Switch to control all your
Multicast traffic. Products from
Foundry, Extreme, Nortel and
Cisco (to name just a few) should
be used.
Encoder
These are typically non-hardened
products
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
L2 Switch
Encoder
Several vendors offer a wide range of
products for this application. Several
(including Magnum 6Ks from
GarrettCom) were tested at iMPath with
positive results.
Multi-Vendor Support
iMPath
Avoid…
Networks
L3 Switch
L2 Switch
Manufacturer A
Encoder
L2 Switch
Manufacturer A
Do not MIX
different vendors
IGMP Snooping
switches in this
topology. It will
most-likely not
work
Encoder
Decoder
L2 Switch
Manufacturer A
Encoder
L2 Switch
Manufacturer A
Encoder
L2 Switch
Manufacturer B
Encoder
L2 Switch
Manufacturer A
Encoder
L2 Switch
Manufacturer B
Encoder
Although some L2 IGMP Snooping Switch vendors
may suggest they can integrate into a multi-vendor
solution, this is not recommended since IGMP
Snooping is not a RFC standard. Implementation
differs between manufacturers. (Proven to fail in our
labs)
Multi-Vendor Support
iMPath
Recommendation…
Networks
When multi-vendor solutions are used, it is recommended to use a single manufacturer solution on each link. Use
the L3 Switch to separate each group (manufacturer) of L2 IGMP switches.
This is the most reliable topology to support multi-vendor solutions.
Manufacturer A
Manufacturer B
L3 Switch
Decoder
Manufacturer C
Manufacturer B
Manufacturer C
Manufacturer A
iMPath
Credits
Networks
• The information shared in this document was obtained by performing
numerous IGMP related tests at iMPath facilities between January and
June 2005.
– Tests were performed using L2, L2 IGMP Snooping, and L3
switches.
– Over 30 MPEG-2 iMPath Encoders were used during these tests to
validate the proper function and performance of the switches
under stress.
• iMPath would like to thank its business partners for their participations
and providing equipment and support during the research phase.
– L2 IGMP Snooping switch manufacturers
• GarrettCom, as well as Etherwan, IFS, Ruggedcom
– L3 switch manufacturer
• Foundry Networks
• Test Coordinator
– iMPath Networks, Daniel Brisson, Sr. System Engineer