Avaya P580 - Manual (Page 545)

Avaya P550R, P580, P880, and P882 Multiservice Switch User Guide, v5.3.1 16-3
Managing Intelligent Multicasting
Dynamic Intelligent Multicasting
In an environment that uses IGMP (and an IP multicast routing
protocol, optionally), Dynamic Intelligent Multicasting may be used.
The ability of the switch to dynamically set up sessions and add or
remove client and router ports is particularly useful in a flexible
multicast environment where there are many multicast sessions to
administer. The protocols and mechanisms used to perform
Intelligent Multicasting are enabled or disabled across all VLANs on
a switch. The Dynamic Intelligent Multicasting process is split into
three parts: Learning, Administration, and Dissemination.
The Learning
Process, IGMP
Snooping
To learn which sessions must be configured, or which client or
router ports must be added or removed, a mechanism to draw that
information from the layer 3 protocols must be enabled. For the
Avaya Multiservice Switch, IGMP Snooping is that mechanism.
IGMP Snooping can learn about multicast sessions from IP interfaces
that reside on the same switch.
* Note: IGMP Snooping is only available for VLANs that have an
IGMP interface enabled.
Enabling DVMRP on an interface also enables IGMP.
The
Administration
Process;
Management
and Pruning
At the core of all Intelligent Multicast functionality, the
Administration Process is manipulated by manual configuration and
dynamic configuration, and implements a pruning function. In a
dynamically configured environment, the Administration Process
takes the information from the Learning Process (from IGMP
Snooping) or from one of the clients in the Dissemination Process
and creates the AFT table entries which will perform the actual
Intelligent Multicast functionality on the local switch. It also passes
the new information to the servers in the Dissemination Process for
distribution to other switches in the same VLAN.
The Administration Process views all data inputs as applications.
Manual configuration is the MGMT (management) application,
IGMP Snooping is the IGMP application, the LGMP client is the
LGMP application, and the CGMP snooper is the CGMP application.
The pruning functionality of the Administration Process is a cleanup
facility that prevents stale information from existing in the
Intelligent Multicast tables in the event an application fails to
perform its own cleanup. There are three types of pruning, each
with their own timers: session, client port, and router port.