N o t e s

Multimedia Traffic Control with IP Multicast (IGMP)

Excluding Multicast Addresses from IP Multicast Filtering

Excluding Multicast Addresses from IP Multicast Filtering

Each multicast host group is identified by a single IP address in the range of

224.0.0.0through 239.255.255.255. Specific groups of consecutive addresses in this range are termed “well-known” addresses and are reserved for predefined host groups. IGMP does not filter these addresses, so any packets the switch receives for such addresses are flooded out all ports assigned to the VLAN on which they were received (except the port on which the packets entered the VLAN).

The following table lists the 32 well-known address groups (8192 total addresses) that IGMP does not filter on the switches covered in this guide, as well as on the 1600M, 2400M, 2424M, 2650M, 4000M, 6108M, 8000M, and Switch 2500 Series devices.

4-3.IP Multicast Address Groups Excluded from IGMP Filtering

Groups of Consecutive Addresses in

Groups of Consecutive Addresses in

the Range of 224.0.0.X to 239.0.0.X*

the Range of 224.128.0.X to 239.128.0.X*

 

 

 

 

224.0.0.x

232.0.0.x

224.128.0.x

232.128.0.x

225.0.0.x

233.0.0.x

225.128.0.x

233.128.0.x

226.0.0.x

234.0.0.x

226.128.0.x

234.128.0.x

227.0.0.x

235.0.0.x

227.128.0.x

235.128.0.x

228.0.0.x

236.0.0.x

228.128.0.x

236.128.0.x

229.0.0.x

237.0.0.x

229.128.0.x

237.128.0.x

230.0.0.x

238.0.0.x

230.128.0.x

238.128.0.x

231.0.0.x

239.0.0.x

231.128.0.x

239.128.0.x

* X is any value from 0 to 255.

Reserved Addresses Excluded from IP Multicast (IGMP) Filtering.

Traffic to IP multicast groups in the IP address range of 224.0.0.0 to 224.0.0.255 will always be flooded because addresses in this range are “well known” or “reserved” addresses. Thus, if IP Multicast is enabled and there is an IP multicast group within the reserved address range, traffic to that group will be flooded instead of filtered by the switch.

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