Chapter 2: About the HSIM-W6
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.
