AUTOMATIC IP CONFIGURATION
This chapter explains more about IP addresses and how automatic IP configuration works on the Switch.
For details on how to view and amend your Switch’s IP settings, refer to “IP Settings” on page 23.
Switch’s MAC address in the DHCP server’s lease list. Refer to “IP Settings” on page 23.
3Com recommends that you do not use DHCP Addressing, unless you have experience of configuring and managing a DHCP server.
How Your Switch Obtains IP Information
Your Switch can obtain IP information using one of the following methods:
■Automatic IP Configuration (default) — the Switch will configure itself with its default IP address 169.254.x.y,where x and y are the last two bytes of the Switch’s MAC address.
Refer to “Automatic Process” on page 19 for details on how the Switch automatically obtains IP address information.
■Static IP Configuration — you can manually input the IP information (IP address, subnet mask, and default gateway). Refer to “IP Settings” on page 23. If your computers are configured with static addresses and you do not wish to change this, then you should use the Discovery program on the Switch
For details on how to use Discovery to detect the Switch on the network, refer to “Using Discovery” on page 39.
■DHCP Addressing — DHCP addressing is a dynamic mechanism which the Switch uses to obtain an IP address lease from the DHCP server which is located on your network. If you select DHCP addressing, you will only be able to find out the IP address of the Switch by cross referencing the
How Automatic IP Configuration Works
When your Switch is powered up for the first time the IP configuration setting is set to automatic — this is the default setting.
If your Switch has been powered up before, whichever of the three options for IP configuration (automatic, static or DHCP) was last configured is activated when the Switch powers up again.
Automatic Process
To detect its IP information using the automatic configuration process, the Switch goes through the following sequence of steps:
1The Switch tries to configure itself with the default IP address 169.254.x.y,where x and y are converted from the last two bytes of the Switch’s MAC address.
For example, if the MAC address is 08004E000102, the IP address would be 169.254.1.2. This address is used if the Switch is operating in a standalone mode, or no other Switches on the network have this IP address.
2If this default IP address is already in use on the network then the Switch detects this, and increments the last byte of the MAC address by one to generate its IP address. The IP address would therefore become 169.254.1.3.
19
