Cabletron Systems HSIM-W6 - Manual (Page 31)

Chapter 2: About the HSIM-W6
HSIM-W6 User’s Guide 17
Routing — Routing provides a way to transfer user data from source to destination over different
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 through inter-router protocols). Routing helps to increase
network capacity by localizing traffic on LAN segments and broadcasts that would result from
bridged traffic. It also provides security by isolating traffic on segmented LANs. Routing extends
the world-wide reach of networks.
HSIM-W6 Bridging and Routing — The HSIM-W6 can operate as a bridge, a router, or both.
The HSIM-W6 operates as a router for network protocols that are supported when routing is
enabled and operates as a bridge when bridging is enabled. When both bridging and routing are
enabled, routing takes precedence over bridging (i.e., the HSIM-W6 uses the protocol address
information of the packet to route the packet to the correct destination, and if the protocol is not
supported, the device uses the MAC address information to bridge the packet).
Operation of the HSIM-W6 is influenced by routing and bridging controls and filters set during
HSIM-W6 configuration. General IP routing, and routing or bridging from specific remote routers
are controls set during the configuration process.
IEEE 802.1d Bridging — The HSIM-W6 supports the IEEE 802.1d standard for LAN to LAN
bridging. This bridging algorithm learns the low-level MAC addresses of each LAN constituent
and uses this information to decide whether to transmit the packet to another LAN via a WAN
connection, or keep it local. Part of the bridging standard used, called Spanning Tree Protocol,
supports multiple, redundant paths for LAN to LAN bridging, yet prevents data loops and
duplication. This adds fault tolerance to a system of LANs, since, if one WAN data path fails,
another may be substituted automatically.
IP Routing — IP routing support provides the ability to process TCP/IP frames at the network
layer for routing. IP routing support includes the Routing Information Protocol (RIP) that allows
the exchange of routing information on a TCP/IP network. The HSIM-W6 receives and broadcasts
RIP messages to adjacent routers and workstations.
IPX Routing — Internet Packet Exchange (IPX) routing support provides the ability to process
Novell proprietary frames at the network layer for routing. IPX routing support includes the
Routing Information Protocol (RIP) that allows the exchange of routing information on a Novell
NetWare network.