[c-nsp] Strange NAT and DHCP Problem

[Manu Chao]

3/ MAC and/or Client ID depend on your hosts network setting

By default, DHCP implementations typically employ the client's MAC address
but you can add Client ID option if you want specific DHCP reply for hosts
with different Client IDs or host without

On Mon, Jul 20, 2009 at 9:48 AM, Andy Saykao <
andy.saykao at staff.netspace.net.au> wrote:

> 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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