From: Kenneth Wygand (KWygand@customonline.com)
Date: Fri Jul 09 2004 - 10:11:24 GMT-3
Tim,
Yes, DHCP is "smart enough" not to distribute those host addresses.
Here is the logic:
When you configure a pool of addresses in the DHCP pool, you give it the
network number (0's in host portion) and the prefix length (or
equivalent subnet mask). The DHCP service knows not to give out the all
0's or all 1's address for the host portion. If the DHCP valid
addresses were entered into the IOS like the excluded addresses
(starting IP address and ending IP address), then DHCP might not be "so
smart".
It should be noted, however, that IP addresses you list in the various
DHCP options (Default Network/Gateway, DNS, WINS, etc), all *MUST* be
excluded from the range if they fall in the network portion you
configured (obviously the default network/gateway must be in this local
address range).
Also, according to Scott Morris (I haven't tested this, so I use this
disclaimer :) [Hi Scott!]), if you configure manual bindings in
alternate DHCP pools, but the manual binding is part of the dynamic
range in your first pool, the IOS actually creates a binding for that
manually-bound address so it won't attempt to give out that IP address
in the dynamic range. As a result, you don't need to exclude manual
bindings from the dynamic range.
This does make sense since once the network ranges or host "range" is
configured, the "excluded-addresses" are defined globally on the router,
not within a specific range.
HTH!
Kenneth E. Wygand
Systems Engineer, Project Services
CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
Network+, A+
Custom Computer Specialists, Inc.
"The only unattainable goal is the one not attempted."
-Anonymous
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
ccie2be
Sent: Friday, July 09, 2004 7:04 AM
To: Group Study
Subject: DHCP
Hi guys,
Is dhcp smart enough to know not to distribute invalid ip host addresses
such
as 172.16.15.0/24 and 172.16.15.255/24 or do we have to manually exclude
these
addresses?
TIA, Tim
This archive was generated by hypermail 2.1.4 : Sun Aug 01 2004 - 10:11:50 GMT-3