Multicast Address Properties - Cisco Small Business 200 Series Administration Manual

Multicast
Multicast Forwarding
The system maintains lists of Multicast groups for each VLAN, and this manages the Multicast information
that each port should receive. The Multicast groups and their receiving ports can be configured statically or
learned dynamically using IGMP or MLD protocols snooping.
Multicast Registration (IGMP/MLD Snooping)
Multicast registration is the process of listening and responding to Multicast registration protocols. The
available protocols are IGMP for IPv4 and MLD for IPv6.
When IGMP/MLD snooping is enabled in a device on a VLAN, it analyzes the IGMP/MLD packets it receives
from the VLAN connected to the device and Multicast routers in the network.
When a device learns that a host is using IGMP/MLD messages to register to receive a Multicast stream,
optionally from a specific source, the device adds the registration to the MFDB.
The following versions are supported:
• IGMP v1/v2/ v3
• MLD v1/v2
NOTE
When IGMP/MLD Snooping is enabled globally or on a VLAN, all IGMP/MLD packets are forwarded to the
CPU. The CPU analyzes the incoming packets, and determines the following:
• Which ports are asking to join which Multicast groups on what VLAN.
• Which ports are connected to Multicast routers (Mrouters) that are generating IGMP/MLD queries.
• Which ports are receiving PIM, DVMRP, or IGMP/MLD query protocols.
These VLANs are displayed on the IGMP/MLD Snooping page.
Ports, asking to join a specific Multicast group, issue an IGMP/MLD report that specifies which group(s) the
host wants to join. This results in the creation of a forwarding entry in the Multicast Forwarding Data Base.

Multicast Address Properties

Multicast addresses have the following properties:
• Each IPv4 Multicast address is in the address range 224.0.0.0 to 239.255.255.255.
• The IPv6 Multicast address is FF00:/8.
Cisco Small Business 200 Series Smart Switch Administration Guide
The device supports IGMP/MLD Snooping only on static VLANs. It does not
support IGMP/MLD Snooping on dynamic VLANs.
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