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ROS™ v3.5 204 RS400
8.3 Troubleshooting
Problem One
When I start a multicast traffic feed it is always distributed to all members of the VLAN.
Is IGMP enabled for the VLAN? Multicasts will be distributed to all members of the VLAN unless
IGMP is enabled.
Problem Two
Computers on my switch receive the multicast traffic just fine, but I can’t get the stream
through a connected router.
Is the port used to connect the router included in the Router Ports list?
To determine whether the multicast stream is being delivered to the router, run the Ethernet
Statistics menu View Ethernet Statistics command. Verify that the traffic count transmitted to
the router is same as the traffic count received from the multicasting source.
Problem Three
The video stream at one of my end stations is of pretty poor quality.
Video serving is a resource-intensive application. Because it uses isochronous workload, data
must be fed at a prescribed rate or end users will see glitches in the video. Networks that carry
data from the server to the client must be engineered to handle this heavy, isochronous
workload.
Video streams can consume large amounts of bandwidth. Features and capacity of both server
and network (including routers, bridges, switches, and interfaces) impact the streams.
You should not exceed 60% of the maximum interface bandwidth. For example, if using a 10
Mbps Ethernet, you should run a single multicasting source at no more than 6 Mbps, or two
sources at 3 Mbps.
Router ports will carry the traffic of all multicast groups, so it is especially important to consider
these ports in your design
Note that multicasting will definitely introduce latency in all traffic on the network. Plan your
network carefully in order to account for capacity and latency concerns.
Problem Four
Multicast streams of some groups are not forwarded properly. Some segments without
subscribers receive the traffic while some segments with subscribers don’t.
Ensure do not have a situation where different multicast groups have multicast IP addresses
that map to the same multicast MAC address. The switch forwarding operation is MAC address
based and will not work properly for several groups mapping to the same MAC address.
Problem Five
Computers on my switch issue join requests but don’t receive multicast streams from a
router.
Is your multicast router running IGMP version 2? It must run IGMP version 2 in order for IGMP
Snooping to operate properly.