[c-nsp] Strange NAT and DHCP Problem

[Church, Charles]

The infinite DHCP entry is probably a BOOTP client, which doesn't have
the concept of a lease.  There are knobs (ip dhcp bootp ignore) that can
turn off bootp, and only allow DHCP.  I think by default, it'll service
both.

Chuck

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Andy Saykao
Sent: Monday, July 20, 2009 3:49 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] Strange NAT and DHCP Problem


Hi All,
 
Just a few questions about DHCP and some strange NAT entries.
 
1/ What can cause this strange NAT entry where there's no protocol,
outside local/global defined??? I'm always seeing it in the NAT able.
 
core2#sh ip nat trans
Pro Inside global         Inside local          Outside local
Outside global
--- 210.15.240.8          172.16.75.111         ---
---
 
Seems to be giving me a warning message whenever it can't use the inside
global IP when there are active translations in place:
 
%IPNAT-4-ADDR_ALLOC_FAILURE: Address allocation failed for
172.16.75.111, pool NAT-POOL might be exhausted
 
2/ How is it possible that a DHCP client (172.16.75.113) has been able
to have their lease expiration time set to "infinite" when I haven't set
any lease time within the DHCP config so it should default to 1 day (see
below). 
 
3/ Any reasons why a DHCP client might prefer to send their own
Client-ID (0065) instead of their MAC address as shown for
172.16.75.111? (see below).
 
core2#sh ip dhcp binding
IP address       Client-ID/              Lease expiration        Type
                 Hardware address
172.16.75.111    0065                    Jul 21 2009 05:34 PM
Automatic
172.16.75.113    0021.e9a0.777c          Infinite
Automatic
 
The DHCP config is pretty straight forward:
 
ip dhcp pool Wireless-512b
   network 172.16.75.0 255.255.255.0
   domain-name netspace.net.au
   default-router 172.16.75.1
   dns-server 210.15.254.240 210.15.254.241
 
Running on Cisco 7606 with IOS 12.2(18)SXF11.
 
Thanks.
 
--

Regards,
 
Andy Saykao
Systems Administrator
Netspace Online Systems Pty Ltd
Phone : 03 9811 0049
Mobile : 0401 422 406
Fax     : 03 9811 0044
E-Mail : andy.saykao at staff.netspace.net.au
<blocked::mailto:andy.saykao at staff.netspace.net.au> 
 

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