Ip Multicast Vlan Overview; Vlan Stacking Mode; Ipmvlan Lookup Mode - Alcatel-Lucent OmniSwitch 6850-48 Network Configuration Manual

Configuring IP Multicast VLAN

IP Multicast VLAN Overview

The IP Multicast VLAN (IPMV) feature helps service providers to create separate dedicated VLANs to
distribute multicast traffic. Service providers have to separate users using these VLANs. This should be
done along with the distribution of broadcast media through IP Multicast across these VLANs without a
router in the distribution L2 switch. To achieve this, the distribution L2 switch needs to perform IGMP
snooping (i.e., allow the switch to "listen in" on the IGMP conversation between hosts and routers) as well
as distribute multicast traffic from one multicast distribution VLAN to many customer ports.
A distribution multicast VLAN that switches into customer ports is invisible to the customer to avoid
packet duplication across the trunk. Furthermore, some service providers use QinQ on the provider ports
to tag the multicast distribution VLAN with a distinct outer VLAN tag. The customer ports can either be
tagged or untagged. However, the multicast traffic always needs to be tagged. This process requires one or
more separate multicast distribution VLANs. These distribution VLANs connect to the nearest multicast
router and are used for multicast traffic only.
The multicast traffic will only flow from the distribution VLAN to the customer VLAN. Customer-gener-
ated multicast traffic will flow only through the customer VLANs so that the multicast router can control
the distribution of such traffic.
The IPMV feature works in both the Enterprise and the VLAN Stacking environment. The ports are classi-
fied as VLAN Stacking ports and Legacy ports (fixed ports/tagged ports). To ascertain that data flow is
limited to either the VLAN Stacking domain or the Enterprise domain, VLAN Stacking ports must be
members of VLAN Stacking VLANs only, while the normal Legacy ports must be members of VLANs
configured in the Enterprise mode only.
It is not possible to change an IPMVLAN from one mode to another. An IPMVLAN configured in a
specific mode must first be deleted, then re-created in the other mode.

VLAN Stacking Mode

IP Multicast VLANs in the VLAN Stacking mode contain VLAN Stacking ports as their member ports. In
an IPMVLAN, the VLAN Stacking network port (NNI) corresponds to the sender port, which also
receives multicast data for the configured multicast group. Only one sender port can be assigned to an
IPMVLAN. The VLAN Stacking user port (UNI) corresponds to the receiver port of the IPMVLAN. An
IPMVLAN can include multiple receiver ports as its members.

IPMVLAN Lookup Mode

In the VLAN Stacking double-tagged mode, single-tagged IGMP reports are double-tagged and sent to the
CPU of the Ethernet switch.
The IP Multicast Switching (IPMS) module can use any one of the following methods to bind
IPMVLANs to a single receiver port:
•
IP address, or
•
CVLAN-tag, received as part of the IGMP report
Note. It is recommended to use any one of the methods on the receiver port and not both.
OmniSwitch AOS Release 6 Network Configuration Guide September 2009
IP Multicast VLAN Overview
page 43-3