Cabletron Systems CyberSWITCH CSX150 User Manual

Also see for CyberSWITCH CSX150: User guide Quick start guide

Contents

USER’S GUIDE248 CyberSWITCHDHCP C ONFIGURATION ELEMENTSDHCP P ROXY C LIENT E NABLE/D ISABLE FLAGA global flag that indicates whether the DHCP Proxy Client feature is enabled or not. The proxyclient is disabled by default.M AXIMUM NUMBER OF IP A DDRESSESRefers to the maximum number of IP addresses obtained from DHCP servers for this networkinterface. This number of IP addresses can be leased from DHCP servers for this interface andplaced into the IP Address Pool. The range of this configuration value is 0 to “x” where “x” is thesize of the Address Pool. The default for this value is 0.Note: If all available entries in the IP Address Pool are assigned to one IP network interfaces’smaximum, there will not be any more available for other interfaces. Therefore, take care toplan accordingly.NUMBER OF IP ADDRESSES TO PRE-FETCHThe configured number of IP addresses to have available at all times for an IP network interface.This means that the IP addresses have been placed in the IP Address Pool, but have not yet beenleased to any remote devices. These IP addresses are sitting in the IP Address Pool waiting to beclaimed by remote devices. The range of this configuration value is 0 to “x” where “x” is themaximum IP addresses to obtain for the IP network interface. The default for this value is 0.LAN PORT ON WHICH TO REACH THE DHCP SERVERThis configuration value contains the number of the LAN port to use in order to reach a DHCPserver. The range of this value is 1 to “x” where “x” is the number of configured LAN ports. Thedefault for this value is 1.DHCP B ACKGROUND INFORMATIONThe DHCP Proxy Client feature enables the CyberSWITCH to dynamically obtain IP addressesfrom a DHCP server for IP host devices that support PPP. This feature compliments the DHCPRelay Agent feature, which supports remote bridges. Both features together allow theCyberSWITCH to access the DHCP server to allocate IP addresses to all types of remote IP devices,rather than maintaining separate IP address pools for separate devices.Remote IP devices that use PPP to connect to the CyberSWITCH use PPP IPCP IP Addressnegotiation to dynamically obtain their IP addresses. In general, those devices are not capable ofusing DHCP to obtain the dynamic IP addresses. However, with the DCHP Proxy Client feature,the CyberSWITCH “pretends” to be a DHCP client. When a connection is established and a remoteIP host device requests an IP address, the CyberSWITCH (acting as a DHCP client) obtains an IPaddress from the DHCP server. It then gives it to the remote device via IPCP.The CyberSWITCH is capable of prefetching some number of IP addresses so that connections canbe established faster. You may configure two numbers for each WAN type network interface: thenumber of the IP addresses to prefetch (“x”), and the maximum number of IP addresses to obtain(“y”). The CyberSWITCH will prefetch “x” IP addresses for the network interface until it hasobtained “y” addresses. For example, if the number to prefetch is 3, and the maximum number is5, then 3 IP addresses will be prefetched immediately. As one IP address is assigned to a remotedevice, one IP address is obtained from a DHCP server until the total of 5 IP addresses have beenobtained.