3com TR ユーザーズマニュアル

C

HAPTER

 1: O

VERVIEW

These connectors provide a high-speed cascade con-
nection between Switch 2000 TRs in a stack. You can 
connect multiple units to form a single switched 
domain. You can connect up to six Switch 2000 TRs 
with these connectors.

A stack of Switch 2000 TRs act as a single multiport 
switch. The setup configuration parameters are 
shared among switches and the entire stack can be 
managed and downloaded as a single IP entity.

This section describes Token Ring Switching and 
unique features of the Switch 2000 TR, including:

■

Why Token Ring Switching?

■

Source Route Bridging

■

Transparent Bridging

■

Source Route Transparent Bridging

■

Spanning Tree (802.1d and IBM)

■

Store-and-Forward

■

Cut-through

■

Dynamic Cut-through

■

Congestion Control

■

Workgroups

Existing Token Ring networks are built around shared 
media technology and typically operate at 16 Mbps 

wire speed. This 16 Mbps of bandwidth is shared 
between all stations on the ring. As applications 
become more sophisticated, or as work-stations 
become more powerful, or as the number of users 
per ring grows, the demand for bandwidth increases. 
As a result, stations are limited not by their own pro-
cessing power but by the limitations of the physical 
network. 

In an effort to reduce the traffic per ring and increase 
the overall bandwidth availability, existing rings have 
been divided into multiple smaller rings. This division 
provides more bandwidth per station. 

With an optional FDDI or ATM downlink module, 
Token Ring switching also solves problems found in 
client-server applications where a shared 100 Mbps 
(FDDI) or 155 Mbps (ATM) pipeline can provide easy 
access to servers and WAN links.

The major benefits of Token Ring switching are:

■

Bandwidth relief

■

Migration path to high-speed technologies

■

Cost-effective method for achieving LAN intercon-
nectivity

Source Route Bridging is a method of allowing a ring 
station (node) on a Token Ring network to communi-
cate with another ring station on a different ring 
interconnected by bridges. The “source” ring station, 
in other words, the node initiating the communica-
tion, is responsible for dynamically determining and 
then maintaining information about the “route” to