Allied Telesis AT-S83 - Manual (Page 33)

AT-S83 Management Software Command Line Interface User’s Guide
33
Switching
Technology
Another key development pushing the limits of Ethernet technology is in
the field of switching technology. A switch bridges Ethernet packets at the
MAC address level of the Ethernet protocol transmitting among connected
Ethernet or Fast Ethernet LAN segments.
Switching is a cost-effective way of increasing the total network capacity
available to users on a LAN. A switch increases capacity and decreases
network loading by making it possible for a LAN to be divided into
segments, which are not competing with each other for network
transmission capacity. Therefore, the load on each segment is decreased.
The switch has a high-speed selective bridge between the individual
segments. Traffic that needs to go from one segment to another (from one
port to another) is automatically forwarded by the switch, without
interfering with other segments (ports). This ability allows the total network
capacity to be multiplied, while still maintaining the same network cabling
and adapter cards.
For Fast Ethernet or Gigabit Ethernet, a switch is an effective way of
eliminating the problem of chaining hubs beyond the two-repeater limit. A
switch can be used to split parts of the network into different collision
domains. For example, the switch can make it possible to expand a Fast
Ethernet network beyond the 205 meter network diameter limit for 100TX
networks. Switches supporting both traditional 10Mbps Ethernet and
100Mbps Fast Ethernet are also ideal for bridging between existing
10Mbps networks and new 100Mbps networks.
Switching LAN technology is a marked improvement over the previous
generation of network bridges which were characterized by higher
latencies. Routers have also been used to segment local area networks,
but the cost of a router and the setup and maintenance required make
routers relatively impractical. The AT-10408XP switch is an ideal solution
to most kinds of LAN congestion problems.
Routing Protocol
Support
The AT-S83 software supports IETF-compliant IPv4 and IPv6 versions of
OSPF (Open Shortest Path First) and RIP (Routing Information Protocol).
The RIP IPv4 Protocol Module supports both RIPv1 and RIPv2. In
addition, OSPFv2 and OSPFv3 protocol modules are provided with IPv4
and IPv6 support.
RIP
A distance-vector protocol, RIP is an Interior Gateway Protocol (IGP) that
uses hop counts as its metric. The AT-S83 software supports RIP module
supports RFCs 1058 and 1723. The RIPv2 module supports more fields in
the RIP packets as well as security authentication features.
At regular intervals of the routing update timer and at the time of change in
the topology, the RIP router sends update messages to other routers. The
listening routers update their route table with the new route, and increase