User manual

Multicast Filtering
6874_en_09 PHOENIX CONTACT 6-1
6 Multicast Filtering
6.1 Basics
Multicast Multicast applications, unlike unicast applications with point-to-point communication, do
not transmit their data with the MAC address of the destination, but with an independent
multicast group address. Always using connectionless communication, a station transmits
one data packet that is received by one or more receiver stations.
Advantages:
1 If, for example, a data packet of a transmitter is to be transmitted to eight receivers,
the same packet does not have to be sent eight times to the addresses of all eight
devices. Instead it only needs to be sent once to the address of the multicast group
that includes the eight devices.
2 When using multicast communication and filtering, the required bandwidth for data
transmission is reduced because each packet can only be transmitted once.
6.2 Enabling the Web Pages for Multicast Filtering in
WBM
Activate WBM for the switches, e.g., using the Factory Manager. Switch to the "General
Configuration" menu, then the "User Interfaces" page. Activate "Multicast Filtering" and
confirm by entering your password.
6.3 Static Multicast Groups
Static multicast groups must be created manually on every switch and all ports that are
used to contact group members need to be added. The advantages of static groups are:
1 Easy specification of network paths on which the multicast data traffic of known groups
is limited.
2 No querier required (see "Query" on page 6-7).
The following marginal conditions must be observed:
– Precise network documentation for path specification is required.
– Possible redundant paths due to Spanning Tree must be taken into account during
port assignment.
A maximum of 20 multicast groups can be created.
When activating "Multicast Filtering" under "General Configuration/User Interfaces", the
multicast mechanism is not activated. In the WBM menu, the "Multicast" page - under
which the function can be configured and activated - is enabled.