Selecting A Switch - G&D ControlCenter-IP-XS Installationsanleitung

Selecting a switch

Selecting a switch
Computer modules (
multicast.
Multicast transmission allows users with »Target multi access« rights to connect to a
computer to which another user is already connected.
IMPORTANT: The multicast streams are controlled by the network switches and
enable efficient distribution of the streams to multiple receivers at the same time.
Requirements of network switches
The following requirements apply to the network:
 Gigabit Ethernet:
GBit network connections (in accordance with IEEE 802.3ab).
 Multicast: The computer modules (
The switch manages the multicast groups and maintains multicast tables.
The Internet Group Management Protocol (IGMP) was designed for organising
 IGMP:
multicast groups. The user modules (
notify the switch which multicast group they want to join or which they want to
leave.
 IGMP snooping: IGMP snooping is the interception of IGMP network traffic through
a network switch. By listening to the IGMP conversation, the switches can deter-
mine which of their own hosts have requested a multicast stream. Only these hosts
are supplied with the required multicast stream.
IMPORTANT: Without IGMP snooping, the switch floods all ports with the multi-
cast stream so that potential users can receive the stream.
Since the multicast stream of a single computer module already uses the full GBit,
packet loss occurs if a port receives more than one multicast stream at the same
time.
 IGMP Snooping Querier:
larly asks all subscribers of a multicast group whether they still want to receive
this group (IGMP query). The answers (IGMP reports) are identified and evalu-
ated by all local switches.
NOTE:
Ports that do not regularly confirm their subscription to the respective
multicast groups no longer receive their packets.
If no querier is available, a switch disables the port after reaching the timeout of a
member port for receiving multicast packets.
6 · G&D ControlCenter-IP-XS
IP-CPU ) send the video stream to user modules (
User and computer modules are connected to the network using 1
An IGMP snooping querier (function of the switch) regu-
IP-CPU ) transmit the video stream via multicast.
) use the protocol (min. IGMPv2) to
IP-CON
IP-CON ) using