Technicolor COM400 Assembly instructions

TECHNICOLOR
9045 River Road, Suite 400
Indianapolis, IN 46240 - USA
Phone [phone]
www.technicolor.com
1 | P a g e
Technical Tip
COM400
IGMP Query Packet Sets COM400 Port as Dynamic Router
If a COM400 receives an IGMP Query packet from a managed ethernet switch it will
automatically assign that port as a “dynamic router port”and force all multicast traffic to flow
across the connected port.
Suggested Action:
It is recommended that managed ethernet switches only be connected to the 10G ports on the
COM400 chassis, and that only management devices such as Laptops be connected to the 1G
ports. It is recommended that the Meraki router be connected to the managed ethernet switch
instead of to the 1G port on the COM400.
If the Meraki router is connected to the 1G port on the COM400, do not connect managed
ethernet switches to the Meraki router as the switch may send the IGMP Join and Query
request through the router to the COM400. This will then trigger the 1G port as a dynamic
router which will flood the Meraki with multicast traffic and prevent remote management. Any
devices downstream from the switch must also not send any IGMP Queries as well.
Background
IGMP Protocol –“10 Thousand Foot View”
When an end device is tuned to receive an IP video stream via multicast it will send an IGMP
Join request to the switch. The switch will then route the requested multicast stream to that
end device.
The Ethernet switch will then send occasional IGMP Query
request packets asking all the end devices to send another
IGMP Join request. If an IGMP Join request is not sent, the
switch will drop that end device from the IGMP group.
Technicolor recommends ports used for Managed Ethernet
switches be set as router port manually, however this
might not be required if the switch receives an IGMP Query
packet.
In a single COM3000 chassis system, normally the COM400
is the only IGMP Querier in the network so IGMP queries
are only transmitted out of the COM3000. But in situations
with more complicated multicast routing, there may be

TECHNICOLOR
9045 River Road, Suite 400
Indianapolis, IN 46240 - USA
Phone [phone]
www.technicolor.com
2 | P a g e
more IGMP Queriers in the network and an IGMP query may come in on an unexpected
COM400 port.
By following the Preferred installation diagram below, there is no risk of an IGMP Query to
come in on an unexpected port on the COM400.
Multicast
End-point
COM400
1G Port
10G router port
IP Router
Preferred Installation:
Installing the managed Layer 2 switch in this
configuration will ensure IGMP Query request
packets only pass through the 10G port. The
managed layer 2 switch will properly forward
multicast traffic only to the requested multicast
endpoints and the router will not be flooded
with unsolicited traffic.
All Multicast Traffic
IGMP requested stream

TECHNICOLOR
9045 River Road, Suite 400
Indianapolis, IN 46240 - USA
Phone [phone]
www.technicolor.com
3 | P a g e
Multicast
End-point
COM400
10G router port
IP Router
Problematic Installation:
Installing a managed Layer 2 switch in this configuration
might send IGMP query packets through the router’s switch
ports and activate the 1G COM400 ports as dynamic router
ports. This will cause the COM400 to send all Multicast traffic
across the 1G ports, flooding the router with multicast traffic.
Be sure there are no IGMP Queriers active elsewhere in the
network below the router or the second layer 2 switch in this
configuration.
All Multicast Traffic
IGMP requested stream
1G Port