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Table of Contents
Mapping devices into NAV's data model
This page tries to summarize the different physical ways that network devices are internally organized, and how this is mapped into NAV's data model. If you disover factual errors in the device descriptions used here, please don't hesitate to fix them :)
Chassis, stacking, clustering etc.
Different vendors use different terminology to describe their own implementations of these concepts. We will use our own terminology here, but attempt to translate into the names used by the vendors best known to us.
Standalone devices
Standalone devices are the simplest kind. A standalone device consists of a single physical box with few or no options for expansion. This is your typical simple N-port switch. All vendors provide something like this.
Chassis devices
A chassis devices doesn't provide much functionality in itself, it is mostly just a container with slots to fill with expansion cards that make up the important functions of the box.
Most large Cisco routers or switches with router functionality are of this kind.
Physical stacks
Some vendors provide a way to combine several otherwise standalone devices into a single functional unit, through the use of a special stacking cable. The stacking cable connects to a stacking port on each device, and functions as a backplane for communication between the devices. Usually, one of the devices in the stack is assigned the role of commander; this device takes an IP address, manages the stack as a whole and presents the stack as single device to SNMP management stations.
Both 3Com and Cisco are known to have products that are capable of this kind of stacking.
Virtual stacks
Some vendors provide a way to virtually stack multiple standalone devices by connecting them by their regular ethernet ports. Typically, one device in such a stuck is assigned the role of commander, while the other devices take the role of members. The commander will have an IP address and provide management facilities for the stack as a whole. BUT, the commander will not present the stack as a single physical unit to the management station. Each device in this stack operate independently of each other; the commander will allow the management station to communicate with each stack member by addressing them with a modified SNMP community string.
