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Chapter 1
Overview
CentreCOM AT-3675 SNMP-Manageable Bridge
The CentreCOM
AT-3675 SNMP-Manageable Learning Bridge allows you
to interconnect two Ethernet sub-networks. Each sub-network may be IEEE
802.3 10BASE2 (thin) Ethernet or 10BASE5 (thick) Ethernet or pre-802.3
Ethernet. Unshielded Twisted Pair (UTP) can also be connected to the bridge
through a transceiver. The AT-3675 bridge transparently forwards packets.
Since the bridge operates at the Media ACcess (MAC) level, all higher level
protocols, such as Transmission Control Protocol (TCP), DECnet™ and
NetWare®, are passed unaffected.
Performance
The four repeater rule does not apply across the bridge. The effective length
of a Local Area Network (LAN) can be increased by adding a CentreCOM
AT-3675 SNMP-Manageable Learning Bridge. Placing bridges at natural
boundaries of the workgroups increases the network performance at each
segment by diminishing network traffic. The reliability of a large network can
be enhanced by a bridge and allows sub-networks of different media types to
be interconnected.
The CentreCOM AT-3675 is self-learning, adjusting to reconfiguration of sub-
nets to provide continuous isolation of local traffic. The AT-3675 provides
packet filtering at 25,000 Packets Per Second (PPS) and sustained forwarding
at 12,500 PPS. Its filter table supports 2,048 MAC-level station addresses.
Multiple AT-3675 bridges can be used as backups in case of network failure.
The AT-3675 supports the IEEE 802.1 Spanning Tree Protocol (STP), which
provides redundancy link management and network loop checking. STP
allows backup bridges to provide fault tolerant networks by placing the
bridges that form loops into a standby state until an active bridge fails. When
failure occurs, the network is reconfigured and any loops are eliminated. This
network reconfiguration occurs without impacting the network users or the
applications.
