Technical data

16
Numerous network protocols have evolved and within each protocol are associated protocols for routing, error
handling, network management, etc. The following chart displays the networking and associated protocols
supported by the router.
Most of the router’s operation on each protocol level is transparent to the user. Some functions are influenced by
configuration parameters and these are described in greater details in the following sections.
Bridging
Bridging connects two or more LANs together so that all devices share the same logical LAN segment and
network number. The MAC layer header contains source and destination addresses used to transfer frames.
An address table is dynamically built and updated with the location of devices when the frames are received.
Transparent bridging allows locally connected devices to send frames to all devices as if they are local.
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 allows optimizing internetwork capacity by
localizing traffic on LAN segments. A bridge extends the physical reach of networks beyond the limits of each
LAN segment. Bridging can increase network security with filtering.
The router bridging support includes the IEEE 802.1D standard for LAN-to-LAN bridging and the Spanning Tree
Protocol for interoperability with other vendors’ bridge/routers. Bridging is provided over PPP as well as adjacent
LAN ports.
Most of the router’s bridging operation is transparent. Some functions are influenced by configuration parameters
and these are described in greater detail in the following sections.
Network Protocol Associated Protocol Description
Internet Protocol
(IP)
Routing Information Protocol (RIP) Protocol used to maintain a map of
the network
Address Resolution Protocol (ARP) Maps IP addresses to datalink
addresses
Reverse Address Resolution Protocol (RARP)
a
a Used only during a network boot
Maps data link addresses to IP
addresses
Internetwork Control Message Protocol
(ICMP)
Diagnostic and error reporting/
recovery
Simple Network Management Protocol
(SNMP)
Network Management
Internet Packet
Exchange (IPX)
Routing Information Protocol (RIP)
b
b IPX-RIP is a different protocol from IP-RIP and includes time delays
Protocol used to maintain a map of
the network
Service Advertising Protocol (SAP) Distributes information about service
names and addresses