22. Multicast Filtering
ROX™ v2.2 User Guide
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RuggedBackbone™ RX5000
The Multicast Filtering form can be accessed in two locations: interface/switch and then clicking on a
submenu (for example, lm1/1) or interface/trunks and then clicking on a submenu (for example, 1).
GMRP
Synopsis: string - one of the following keywords { learn_advertise, advertise_only }
GMRP (GARP Multicast Registration Protocol) operation on the port. There are several GMRP
operation modes:
• DISABLED : the port is not capable of any GMRP processing.
• ADVERTISE ONLY : the port will declare all MCAST addresses existing in the switch (configured
or learned) but will not learn any MCAST addresses.
• ADVERTISE and LEARN : the port will declare all MCAST Addresses existing in the switch
(configured or learned) and can dynamically learn MCAST addresses.
22.4. 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 the
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.
