Transmission Methods - Bosch PRAESENSA Installation Manual

PRAESENSA
Additional information:
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Notice!
When a DHCP‑server is added to an existing PRAESENSA network in which the devices already
have a Link‑Local IP‑address, then these devices will query a new IP‑address from the
DHCP‑server and get a new address assigned. This results in temporary network disconnects.
When a DHCP‑server is removed from an existing PRAESENSA network, initially all devices will
continue to work with their assigned IP‑addresses. However, when the lease time expires,
they will revert back to a Link‑Local IP‑address. Since every device will do this at a different
moment, this will lead to system instability for a prolonged time. It is better to switch off the
power to the system, remove the DHCP‑server and switch the system on again.
Caution!
When part of a PRAESENSA system is powered down, including the DHCP‑server, while the
rest of the system remains in operation, then, upon restart of the DHCP‑server, some
DHCP‑servers may assign an IP‑address to a restarting PRAESENSA device that is already in
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use by one of the devices in operation. This will result in unexpected behavior of the system
and requires a power cycle of the whole system, to renew all IP‑addresses. Also the
DHCP‑server function of the PRA-ES8P2S switch is suffering from this behavior; therefore this
function is disabled by default and it is advised not to enable and use it.
4.6.11

Transmission methods

IP‑communication takes place using the following transmission methods:
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Bosch Security Systems B.V.
Some devices have multiple IP‑addresses. This refers to devices that contain multiple
Network Interface Cards (NICs) or to the protocols they are using. Examples are the
system controller and the call station, which contain a controller IP‑address and an audio
IP‑address.
Managed switches need a valid IP‑address to change the configuration.
Unicast is used for one‑to‑one, also known as point‑to‑point, transmission with one
sender and one receiver. A switch detects which port a unicast IP‑address is connected
to and only forward packets to this port.
1
Broadcast is used for one‑to‑all transmission with one sender and multiple receivers.
With broadcast, the packets are sent to all devices in the subnet or VLAN. The data is
then processed by the devices that need it, but ignored by others that do not. However,
the bandwidth on the link is still utilized by sending this information.
General installation procedures and instructions | en
1 Sender
2 Receiver
2
Installation manual
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2019.11 | V1.00 |