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Cisco CNS Network Registrar User’s Guide
OL-6240-02
Chapter22 Advanced DHCP Server Properties
Tuning the DHCP Server
•Windows:
–
For Tcl—\program files\Network Registrar\extensions\dhcp\tcl
–
C or C++—\program files\Network Registrar\extensions\dhcp\dex
It is best to place these extensions in the appropriate directory for TCL or C/C++ extensions. Then, when
configuring the filename, just enter the filename itself, without slash (/) or backslash (\).
If you want to place extensions in subdirectories, enter the filename with a path separator. These are
different depending on the operating system on which your DHCP server is running.
Note When entering a filename that contains a backslash (\) character in Windows, you must enter it
with a double-backslash (\\), because backslash (\) is an escape character in the CLI. For
example, enter the filename debug\myextension.tcl as debug\\myextension.tcl.
Step2 Use the extension command to configure the DHCP server to recognize this extension.
Step3 Attach the configured extension to one or more DHCP extension points using dhcp attachExtension.
Step4 Reload the server.
Tuning the DHCP Server
Other helpful hints in tuning your DHCP performance include:
•Set the request (max-dhcp-requests) and response (max-dhcp-responses) buffers for optimal
throughput. See Table22-1 on page 22-4 for details.
•Keep the defer-lease-extensions attribute enabled. This reduces writes to the database.
•Set the last-transaction-time-granularity attribute to at least 60 seconds, optimally a value greater
than half your lease interval.
•Disable the allow-lease-time-override attribute for policies offering production leases.
•Minimize your logging and debugging settings. If you require logging, use the log-settings attribute
for the DHCP server with a controlled number of attributes, as described in Table 22- 2.
Table22-2 DHCP Log Settings
Log Setting
(Numeric Equivalent) Description
default (1) Displays basic DHCP activity logging (the default setting).
incoming-packets (2) Logs a separate line for each incoming DHCP packet (the default).
missing-options (3) Displays missing policy options expected by a client (the default).
incoming-packet-detail (4) The same as incoming-packets, but in human-readable form.
outgoing-packet-detail (5) Logs each incoming DHCP packet in a human-readable form.
unknown-criteria (6) Logs whenever a client entry has a selection-criteria or
selection-criteria-excluded that is not found in any scope appropriate for
that client’s current network location.
dns-update-detail (7) Logs each sent and replied DNS update.