Bosch PRAESENSA, Installation Manual

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174 en | Application notes PRAESENSA
2019.11 | V1.00 | Installation manual Bosch Security Systems B.V.
17 Application notes
Sometimes applications using PRAESENSA have very specific requirements or face special
installation challenges. This chapter shows possible solutions to some of them.
17.1 Connecting 100 Mbps-devices
Some Dante devices only have a 100BASE‑TX connection, but also many control devices, like a
Fire Alarm system, only support a 100BASE‑TX connection. This is also the case for the Bosch
Smart Safety Link. Devices that have a low speed 100BASE‑TX network interface are only
allowed at the endpoints of a PRAESENSA network and may not be looped through. But even
if such a device is connected as an endpoint, the maximum number of audio channels on the
network must be taken into consideration. PRAESENSA uses multicast traffic which is actually
broadcast within the subnet to all switch ports. Because every OMNEO channel requires
2.44
Mbps, the number of (multicast) OMNEO audio channels must be kept below 20 , to not
exceed the available network bandwidth.
When
more than 20 simultaneous multicast audio channels are needed on the network, it
must be avoided that all this traffic is forwarded to the 100 Mbps link. This is possible by
using a switch with IGMP‑snooping. The low speed 100 Mbps‑devices must then be connected
to a port on the switch that runs IGMP‑snooping on that port. OMNEO devices may be
connected to other ports of that switch, but for these ports IGMP‑snooping must be disabled
and these ports should
not filter multicast traffic.
Notice!
It is very important that OMNEO or Dante devices are not connected behind a port that uses
IGMP‑snooping. See
Network switches, page 28 .
Notice!
Dante devices that are based on the Audinate’s Ultimo chip (e.g. Dante AVIO audio network
adapters, Atterotech u) are limited to a 100BASE‑TX connection. When such a
device is used, the maximum number of simultaneous OMNEO audio channels in PRAESENSA
is 20.
17.2 Long range interconnections
Copper CAT‑wiring for Ethernet is limited to a distance of 100 m between nodes. Longer
distances can be covered by using Gigabit fiber interconnections with SFP transceivers. Some
PRAESENSA devices have one or more SFP sockets for this purpose. But call stations need
Power over Ethernet (PoE), which cannot be transported on fiber connections. For distances
above 100
m there are several possibilities:
– It is possible to use special Ethernet cables that deliver 1 Gbps and PoE+ over 200 m and
pull and terminate like a CAT6 cable.
See Gamechanger cables (
http://www.paigedatacom.com/ ).
– Use one or more Gigabit PoE Ethernet extenders/repeaters. Typically, up to four or five
can be daisy chained, each one adding a new stretch of 100
m, up to around 600 m in
total. The repeaters themselves are powered from the incoming PoE source and also
forward PoE to the connected call station. Multiple repeaters may need a PoE+ power
source in order to still have adequate PoE power left for the call station. These extenders
do not need mains power.