ADTRAN NetVanta 3000 Series - Manual

TECHNICAL SUPPORT NOTE
NetVanta 3000 Series Routers
Bridging (Point-to-Point & Multipoint)
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Introduction
Bridging is an OSI Model Layer 2 function. Bridges and switches are often talked about
interchangeably because both of these devices work at the Data Link Layer. Bridges are a step
above a network device called a hub. A hub operates at the Physical Layer, connecting one or
more network devices on the LAN, sharing bandwidth or acting as a termination point for multiple
network devices in a star topology. A bridge is a LAN (Local Bridge) or WAN (Remote Bridge)
device that interconnects network segments and uses the destination MAC address of each frame
of information to determine whether to pass the signal to the other network segment. Bridges can
be used to connect network segments of dissimilar media, extend the number of hosts allowed on
a single segment, or segment data traffic to reduce overall bandwidth usage.
A bridge keeps a forwarding table, which is a list of MAC (or Layer 2) addresses with their
associated interface. If the bridge does not have an entry for a destination address that comes
across, the packet is forwarded to all attached interfaces. All broadcast and multicast packets are
forwarded to all interfaces (flooded).
Care should be used in deciding when to use a bridge. In general, it is only wise to bridge data
that cannot be routed. The NetVanta 3000 Router can route IP while bridging all other protocols.
Local Bridge
Remote Bridge – Like the NetVantas
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Before You Begin
Before configuring and testing a bridging application, verify that the point-to-point network
connection is installed and operational. All cables necessary for network connection installation