Product Manual

74 | Product Architecture
Aprisa SR+ Product Description 1.5.0
Bridge Mode with VLAN Aware
Ethernet VLAN Bridge / Switch Overview
The Aprisa SR+ in Bridge mode of operation is a standard Ethernet Bridge based on IEEE 802.1d or VLAN
Bridge based on IEEE 802.1q/p which forward / switch Ethernet packet based on standard MAC addresses
and VLANs using FDB (forwarding database) table decisions. VLAN is short for Virtual LAN and is a virtual
separate network, within its own broadcast domain, but across the same physical network.
VLANs offer several important benefits such as improved network performance, increased security and
simplified network management.
The Aprisa SR+ Bridge mode (see figure below), is the default mode of operation and it enables the
switching / bridging of Ethernet VLAN tagged or untagged packets within the Aprisa SR+ wireless network
and in and out to the external Industrial LAN network and RTUs devices connected to the Aprisa SR+ wired
Ethernet ports or serial ports through the terminal server function.
Within the Aprisa SR+ Bridge mode, each incoming Ethernet packet is inspected for the destination MAC
address (and VLAN) and looks up its FDB table for information on where to send the specific Ethernet
frame. If the FDB table doesn’t contain the specific MAC address, it will flood the Ethernet frame out to
all ports in the broadcast domain and when using VLAN, the broadcast domain is narrowed to the specific
VLAN used in the packet (i.e. broadcast will be done only to the ports which configured with that specific
VLAN).
The FDB table is used to store the MAC addresses that have been learnt and the ports associated with that
MAC address. If the destination MAC address is one of the RTUs, the packet is then forwarded to the
wireless ports and broadcast as a PMP wireless packet to all the repeater / remote stations. The
appropriate remote then switches the Ethernet packet and forwards it based on its FDB table (based on
the MAC or VLAN & MAC) to the appropriate Ethernet port to the RTU. The RTU can then interpret and
process the Ethernet / IP data and communication is established between the RTU and the initiating
communication device.