Chapter 8 WAN
EMG2926-Q10A User’s Guide
57
Multicast
Traditionally, IP packets are transmitted in one of either two ways - Unicast (1 sender - 1 recipient)
or Broadcast (1 sender - everybody on the network). Multicast delivers IP packets to a group of
hosts on the network - not everybody and not just 1.
Figure 26 Multicast Example
In the multicast example above, systems A and D comprise one multicast group. In multicasting,
the server only needs to send one data stream and this is delivered to systems A and D.
IGMP (Internet Group Multicast Protocol) is a network-layer protocol used to establish membership
in a multicast group - it is not used to carry user data. The EMG2926-Q10A supports both IGMP
version 1 (IGMP-v1) and IGMP version 2 (IGMP-v2).
At start up, the EMG2926-Q10A queries all directly connected networks to gather group
membership. After that, the EMG2926-Q10A periodically updates this information. IP multicasting
can be enabled/disabled on the EMG2926-Q10A WAN interface in the Web Configurator (WAN).
Select None to disable IP multicasting on these interfaces.
8.4 Internet Connection
Use this screen to change your EMG2926-Q10A’s Internet access settings. Click Network > WAN
from the Configuration menu. The screen differs according to the encapsulation you choose.
8.4.1 IPoE Encapsulation
This screen displays when you select IPoE encapsulation.