3Com 3C17304 Getting Started Guide - Page 56

56 CHAPTER 4: PROBLEM SOLVING Solving Stack Formation Problems The IP address is split into two parts: ■ The first part ('192.168.100' in the example) identifies the network on which the device resides ■ The second part ('.8' in the example) identifies the device within the network The natural subnet mask for this example is 255.255.255.0. If your network has a connection to the external IP network, that is, you access the Internet, you must apply for a registered IP address. How do you obtain a registered IP Address? The IP registration system ensures that every IP address used is unique; if you do not have a registered IP address, you may be using an identical address to someone else and your network will not operate correctly. InterNIC Registration Services is the organization responsible for supplying registered IP addresses. The following contact information is correct at time of publication: World Wide Web site: http://www.internic.net If your IP network is internal to your organization only, that is, you do not access the Internet, you may use any arbitrary IP address as long as it is not being used by another device on your network. 3Com suggests you use addresses in the series 192.160.100.X (where X is a number between 1 and 254) with a subnet mask of 255.255.255.0. These suggested IP addresses are part of a group of IP addresses that have been set aside specially for use 'in house' only. If you are having problems with correctly forming a stack, first ensure that Spanning Tree is enabled. If it is enabled, do the following: 1 Power off all units in the stack. 2 Check all the cable connections in the stack. 3 Power on all units in the stack.