DHCP Functionality
As added Cisco accessories are acclimated in SOHO environments, it becomes more
important that they abutment appearance such as Dynamic Host Configuration
Protocol (DHCP). Hosts use DHCP to dynamically access their Internet configuration
instead of actuality configured with a changeless IP abode and added parameters.
The operation is actual simple: Upon connection, a applicant sends a UDP broadcast,
and if receives a specific reply, it configures itself correspondingly. Of course, this
works alone on the anon affiliated LAN articulation or on the segments that are
connected through bridges or routers, which advanced broadcasts.This adjustment can
be used, for example, to abridge workstation management; all reconfigurations
will be agitated on alone on the DHCP server itself, which will accommodate the new
configuration to the workstations.
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Advanced PIX Configurations • Chapter 4 183
The Cisco PIX firewall can act both as a DHCP server and a client. In the
first case, it will apparently be a aperture for a baby arrangement of workstations and
provide them all the advice they charge in adjustment to affix to the Internet.
In its applicant role, it may be a aperture for a arrangement affiliated through a dialup
line, accepting its alfresco interface abode from the ISP’s DHCP server.
Although DHCP functionality on the PIX firewall is accessible on all models of
hardware, it was accurately advised for PIX 501, 506, and 506E, which are used
primarily in SOHO environments.This is why the DHCP appearance the PIX firewall
offers accept some limitations. For example, the DHCP server can alone support
a best of 256 audience (or alike fewer, depending on the firewall model, version,
and license).There is additionally no BOOTP abutment and no failover support; the
current accompaniment of DHCP server or applicant is not replicated over failover link.