System information

306 Switched Observer
example, if a system on port 3 of a switch has a packet destined for port 7, the switch will
create a virtual segment between ports 3 and 7 for the time required to move the packet.
The switch then removes the virtual segment. In this example, two things are ensured: for
the period of time that port 3 communicates with port 7, the bandwidth between port 3 and
7 is not shared with any other stations; and any other port pair can communicate while port
3 and 7 are communicating.
Switches provide the full maximum theoretical bandwidth for port to port communication,
and add to the potential maximum bandwidth of a network by allowing multiple
simultaneous connections between stations. As long as there are no problems on the
network, this is a valid methodology for moving traffic between station. Not only is it
valid, but replacing a shared hub with a switch will almost invariably increase real
throughput. As your network moves from a one-to-many communication environment to a
many-to-many communications environment, your switch will continue to improve
overall data throughput.
When a problem arises on the network, this methodology erects great barriers to
troubleshooting. The very fact that data streams are “hidden” and paths are simultaneously
created and then removed makes this environment much like trying to judge the traffic on
a busy highway with your eyes closed.
Technology Overview
Observer bridges the gap between switches and protocol analyzers by using three methods
for switch management:
1. Statistical sampling technologies that let you see all ports on your switch. This
functionality is included in the standard Observer product.
2. RMON console functionality for switched with embedded RMON. This requires the
RMON Extension for Observer.
3. SNMP console monitoring functionality for switches with embedded SNMP agents.
This requires the SNMP Extension for Observer.
Additionally, since Observer can manage the ports on your switch, you can also use
Packet Capture for any port (or groups of ports if your switch supports this feature)
without first configuring your switch outside of the Observer environment.
A brief discussion of different switch management options will help develop an
understanding of your ability to monitor your switches with Observer.
In general, switches fall into two categories:
• Switches with management options.
• Switches without management options.
Most switches from higher-end (name brand) manufacturers fall into the first category, but
there is a great deal of differentiation between offerings. Some of the lower-cost switches