RAVENNA Networking Guide V1.0/3 9
Selecting Components
Switches
Switches
In order to create aRAVENNA network you will need aLayer 2switch, or switches, that meet the following
requirements:
1. Transmission Speed =Gigbit Ethernet
AGigabit Ethernet switch operating at 1000 Mbit/s is recommended, as opposed to Fast (100 Mbit/s) or Standard
(10 Mbit/s) Ethernet.
2. Synchronization =PTP-Aware
In mc2/Nova73 systems, synchronisation of the RAVENNA streaming network requires aPTP master clock
source. In the current release, this takes the form of aspecially configured DALLIS sync frame which converts
incoming Wordclock, from the master sync reference, to PTP.
In other Lawo systems, you should consider installing aPTP Grandmaster. Currently, Lawo recommends using
Meinberg clock generators.
As aresult, you will require aPTP-aware switch with this feature enabled.
In smaller RAVENNA streaming networks using crystal, sapphire or JADE, it is possible for nodes to
sync to an incoming stream. In this instance, a PTP Grandmaster is not required, and non-PTP
switches may be implemented. Please see "RAVENNA for crystal" or "RAVENNA for sapphire/
Nova17" for more details.
3. Capacity (Non-blocking) =dependent on number of RAVENNA nodes &bandwidth requirements
The capacity of the switch will depend on the number of RAVENNA nodes and their bandwidth requirements. It is
best to choose anon-blocking switch, where all ports are capable of simultaneous Gigbit transfer. This can be
determined by the switch capacity and number of ports -for example, if aswitch has 10 ports, then its capacity
should be at least 20 Gbps (Gigabits per second), to cater for 1Gb Input and Output transmissions per port.
If long distance connections are required, then you should choose a switch that supports fibre optic
modules.
4. Energy Efficient Ethernet (EEE) or Power Saving =OFF
It is important that any EEE, Green Ethernet or power saving features can be disabled, as these can interfere with
RAVENNA's clock signals and real-time buffering.
5. Addressing =Multicast, with IGMPv2
The switch must support multicast addressing. This means that packets sent from asingle device can be
received by multiple nodes at the same time (i.e. one to many). This differs from aunicast data network where
data packets are addressed to asingle receiving node (i.e. one to one).
The switch should also support IGMPv2 Snooping with an active Querier and Fast or Immediate leave.IGMP
Querying/Snooping is atechnique used by network switches to control the forwarding of Multicast data packets.
Aswitch with IGMP Querying/Snooping will forward Multicast data packets only to the ports that are members of
the Multicast group. Whereas, aswitch without IGMP Querying/Snooping will broadcast Multicast data to all of its
output ports. As aresult, the volume of Multicast traffic will be significantly reduced if anetwork switch supports
IGMP Querying/Snooping.
