Configuring Mvr; Configuration Guidelines And Limitations; Default Mvr Configuration - Cisco Catalyst 2950 Software Configuration Manual

Chapter 16 Configuring IGMP Snooping and MVR
MVR eliminates the need to duplicate television-channel multicast traffic for subscribers in each VLAN.
Multicast traffic for all channels is sent only once around the VLAN trunk—only on the multicast
VLAN. Although the IGMP leave and join messages originate with a subscriber, they appear to be
initiated by a port in the multicast VLAN rather than in the VLAN to which the subscriber port is
assigned. These messages dynamically register for streams of multicast traffic in the multicast VLAN
on the Layer 3 device. The access layer switch (S1 switch) modifies the forwarding behavior to allow
the traffic to be forwarded from the multicast VLAN to the subscriber port in a different VLAN,
selectively allowing traffic to cross between two VLANs.
IGMP reports are sent to the same MAC addresses as the multicast data. The S1 CPU must capture all
IGMP join and leave messages from receiver ports and forward them to the multicast VLAN of the
source (uplink) port.

Configuring MVR

These sections include basic MVR configuration information:
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Configuration Guidelines and Limitations

Follow these guidelines when configuring MVR:
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Note For complete syntax and usage information for the commands used in this section, refer to the
Catalyst 2950 Desktop Switch Command Reference for this release.

Default MVR Configuration

Table 16-5
Table 16-5 Default MVR Configuration
Feature
MVR
Multicast addresses
78-11380-04
Configuration Guidelines and Limitations, page 16-13
Default MVR Configuration, page 16-13
Configuring MVR Global Parameters, page 16-14
Configuring MVR Interfaces, page 16-15
Receiver ports cannot be trunk ports. Receiver ports on a switch can be in different VLANs, but
should not belong to the multicast VLAN.
The maximum number of multicast entries that can be configured on a switch (that is, the maximum
number of television channels that can be received) is 256.
Each channel is one multicast stream destined for a unique IP multicast address. These IP addresses
cannot alias between themselves or with the reserved IP multicast addresses (in the
range 224.0.0.xx).
shows the default MVR configuration.
Default Setting
Disabled globally and per interface
None configured
Catalyst 2950 Desktop Switch Software Configuration Guide

Configuring MVR

16-13