With the momentum of the Internet/intranet revolution, TCP/IP is moving to every desktop and server on the network. One of the key issues with TCP/IP is Internet Protocol (IP) address configuration – a manual process for assigning addresses to each and every node on a TCP/IP network. IP address management is one of the most significant problems facing network managers today.

The Dynamic Host Control Protocol (DHCP) is an Internet standard for automating IP address management. A client system – a PC, for example – can use DHCP to automate the process of entering an IP address by querying the DHCP server for the relevant information. The DHCP server provides IP-address, subnet-mask, and default-gateway information so that client machines such as PCs, servers, and workstations can be connected automatically to a network.

DHCP is also useful for laptop users who may want to connect to different locations within an enterprise. With DHCP, laptop users can do this automatically and without having to modify complex configuration files.

• Simplifies IP address management for network managers
• Enables easy configuration and provides scalability for large numbers of remote DHCP servers
• Handles lease extension requests quickly and efficiently, with minimal processing required of the server CPU

HP-UX 10.10 and later versions of the HP-UX 11i Operating System include DHCPv4. HP-UX 11i DHCP Server contains all the benefits inherent in DHCP, plus a number of advantages that are unique to HP’s version. DHCP is available for IPv4 and IPv6 networks. This version is for IPv6 networks and can coexist with DHCPv4 on the same host.

HP-UX 11i DHCP Server supports DHCP clients using software from any vendor – including HP, Microsoft®, and many others – providing improved performance and advanced features. We provide a choice of two configuration methods: either by a graphical interface via CAM or by command line – useful when large numbers of DHCP servers need to be configured.

HP-UX 11i DHCP Server provides superior performance. Large installations generate many thousands of lease transactions per hour, and bursts of one thousand requests per minute are not uncommon. With the HP-UX 11i DHCP Server running on an HP K400 system, lease extensions are routinely granted in less than five milliseconds. The server can field two hundred requests per second indefinitely while consuming only 10 percent of a single CPU.

The HP-UX 11i DHCP Server is also scalable. All of the configuration information is stored in text files that can be easily modified or expanded with your favourite text editor or with tools such as shell scripts, PERL, or sed. The GUI configuration tools are appropriate for single-system administration. Text file configuration allows the configuring of hundreds of pool groups (and the many optional fields) using a relatively simple shell script.

The HP-UX 11i DHCP Server comes with monitoring, debugging, and error-checking tools, which are essential for the network manager.

• A verification tool finds hard-to-spot typographical errors in configuration files.
• A trace tool decodes the packets as they flow in and out and shows the full contents (like a packet sniffer, but much easier to use).
• A dump tool shows the entire internal state of the server while it is running.
• An update tool allows the network manager to modify existing address leases while the daemon is running.
• A preview tool allows the network manager to probe for full groups and service problems.
• The daemon is fully integrated with the HP-UX 11i SYSLOG facility to simplify error logging and reporting.

One unique feature of HP-UX 11i DHCP Server is the call-back facility, which allows the network manager to fully customise the operation of the server. Whenever a lease is granted for an IP address, a user-supplied executable is invoked, with parameters such as MAC address, client ID, IP address, subnet mask, gateway, lease expiry, and hostname. This feature allows the network manager to perform any sort of processing desired on any client that gets a new lease, extends a lease, or is refused a lease.

The processing could range from simply notifying the administrator of the lease, to preparing reports about all current leases, to adjusting the leases using the tools described above, to sending updates to the DNS server about new IP addresses that are now in use.

Many people are noticing the recent emergence of DHCP because software DHCP clients, such as Windows® 95, have appeared quickly. But firmware BOOTP clients are quite pervasive in the form of printers, X-Terminals, and diskless workstations from many vendors.

The HP-UX 11i DHCP Server will support these clients in a completely transparent fashion, delivering static configuration information from /etc/bootptab or dynamic configuration information from /etc/dhcptab (at your option) in a legal BOOTP reply that older clients can understand.

RFCs supported are as follows:

• RFC 951
• RFC 1542
• RFC 1533
• RFC 1395