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About the CyberSWITCH 100 Router
Bridging and Routing
Bridging connects two or more LANs together so that all devices share the same
Bridging —
logical LAN segment and network number. The bridge examines a portion of each network frame
called the header. This header contains control information for the frame. The bridge compares the
destination address of the frame with the address from which the frame was received. If the
address indicates that the sending station and the destination station are on the same side of the
bridge, the frame is discarded. If the addresses indicate that the sending station and the receiving
station are not on the same side, then the bridge forwards the frame to its other interface.
During this process, the bridge formulates a table that allows it to identify which stations are
connected to which LAN segment. The destination addresses of received frames are compared to
this address table and decisions are made to discard, or forward frames, based on the outcome.
Transparent bridging allows locally connected devices to send frames to all devices as if they are
locally connected.
Bridging allows frames to be sent to all destinations regardless of the network protocols used. It
allows protocols that cannot be routed (such as NETBIOS) to be forwarded and optimizes
internetwork capacity by localizing traffic on LAN segments. A bridge extends the physical reach
of networks beyond the limits of each LAN segment. Filters are used to increase network security
in bridged networks.
Routing provides a way to transfer data from source to destination over different
Routing —
LAN and WAN links using one or more network protocol formats. Routing relies on routing
address tables to determine the best path for each packet. Routing tables can be seeded; i.e.,
addresses for remote destinations are placed in the table along with network address masks and a
metric for path latency. Routing tables are also built dynamically; i.e., the location of remote
stations, hosts, and networks, are updated from broadcast packet information. Routing helps to
increase network capacity by localizing traffic on LAN segments and reducing the number of
broadcasts that would result from bridged traffic. Routing also provides security by isolating traffic
on segmented LANs. Routing extends the reach of networks beyond the limits of each LAN
segment.
CyberSWITCH 100 Bridging and Routing —
The CyberSWITCH 100 can operate as a bridge,
as a router, or as both (sometimes called a brouter). The CyberSWITCH 100 operates as a router
for network protocols that are supported when routing is enabled. The router operates as a bridge
when bridging is enabled. When both bridging and routing are enabled, routing takes precedence
over bridging; i.e., the router uses the protocol address information of the packet to route the
packet to the correct destination and if the protocol is not supported, the router uses the MAC
address information to bridge the packet.
CyberSWITCH 100 Advanced User Information 13
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