H3C S3600 Series Operation Manual

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H3C S3600 Series Operation Manual Manual pdf 10 page image

Operation Manual – DHCPH3C S3600 Series Ethernet Switches-Release 1510 Chapter 2 DHCP Server Configuration2-3holds belong to the network segment the interface resides in and are available tothe interface only.II. The structure of an address poolThe address pools of a DHCP server are hierarchically organized in a tree-like structure.The root holds the IP address of the natural network segment, the branches hold thesubnet IP addresses, and the leaves holds the IP addresses that are manually bound tospecific clients. The address pools that are of the same level are sorted by theirconfiguration precedence order. Such a structure enables configurations to be inherited.That is, the configurations of the natural network segment can be inherited by itssubnets, whose configurations in turn can be inherited by their client address. So, forthe parameters that are common to the whole network segment or some subnets (suchas domain name), you just need to configure them on the network segment or thecorresponding subnets. The following is the details of configuration inheritance.1) A newly created child address pool inherits the configurations of its parent addresspool.2) For an existing parent-child address pool pair, when you performs a newconfiguration on the parent address pool:z The child address pool inherits the new configuration if there is no correspondingconfiguration on the child address pool.z The child address pool does not inherit the new configuration if there is already acorresponding configuration on the child address pool.2.1.4 DHCP IP Address PreferencesInterfaces of the DHCP server can work in the global address pool mode or in theinterface address pool mode. If the DHCP server works in the interface address poolmode, it picks IP addresses from the interface address pools and assigns them to theDHCP clients. If there is no available IP address in the interface address pools, theDHCP server picks IP addresses from its global address pool that contains the interfaceaddress pool segment and assigns them to the DHCP clients.A DHCP server assigns IP addresses in interface address pools or global addresspools to DHCP clients in the following sequence:z IP addresses that are statically bound to the MAC addresses of DHCP clients orclient IDsz IP addresses that are ever used by DHCP clients. That is, those in the assignedleases recorded by the DHCP server. If there is no record in the leases and theDHCP-DISCOVER packets sent by DHCP clients contain option 50 fields, theDHCP server assigns the IP address requested by option 50.z The first IP address found among the available IP addresses in the DHCP addresspool.