3Com SuperStack 3 3812 Implementation Manual

Contents

72 CHAPTER 9: U SING A UTOMATIC IP CONFIGURATIONHow Your SwitchObtains IPInformationYour Switch has two ways to obtain its IP address information:■ Automatic IP Configuration (default) — The Switch attempts toconfigure itself by communicating with a DHCP server on thenetwork.■ Manual IP Configuration — You can manually input the IPinformation (IP address, subnet mask, and default gateway).If you select an option for no IP configuration the Switch will not beaccessible from a remote management workstation on the LAN. Inaddition, the Switch will not be able to respond to SNMP requests.How Automatic IPConfigurationWorksWhen your Switch is powered up for the first time the IP configurationsetting is set to auto — this is the default setting.If your Switch has been powered up before, whichever of the threeoptions for IP configuration (manual, auto, none) was lastconfigured is activated when the Switch powers up again.You can switch to manual IP configuration at any time using a serial portconnection to set up the IP information. For more information see theGetting Started Guide that accompanies your Switch.Automatic Process To detect its IP information using the automatic configuration process,the Switch continually attempt to contact a DHCP server on the networkrequesting IP information from the server.If a DHCP server is on the network and working correctly it responds tothe clients request with an IP address (allocated from a pool of availableaddresses) and other parameters such as a subnet mask, default gateway,lease time, and any other options configured in the DHCP server.The way a DHCP server responds is dependant on the DHCP serversettings. Therefore the way your DHCP server responds may be differentto the process outlined.