Problem obtaining IP from a cisco router

shunmugakrishnan shunmugakrishnan at yahoo.co.in
Thu Feb 8 05:40:15 UTC 2007


Hello all,
In the configuration file, you have specified a line
"ip dhcp excluded-address 172.16.208.1
172.16.208.100". The addresses in this range are not
available for DHCP server to assign to the client.
You have hard coded this 172.16.208.15 address to
billing. But since this falls in the range of excluded
address the server is not assigning this address.

If you want to exclude only those two address, try
giving it in seperate lines 
ex: 
ip dhcp excluded-address 172.16.208.1 
ip dhcp excluded-address 172.16.208.100

I dont know much about cisco routers, but I just went
through their documentation, and it reads
"ip dhcp excluded-address low-address [high-address]"
So I thought this might be the problem.

Am I missing something? :)

Thanks & Regards,
S.Shunmuga Krishnan

--- Brad Stockdale <brad_lists at greenepa.net> wrote:

> Hello all,
> 
>     I've ran into an interesting situation which may
> or may not be 
> related to dhclient. It could very possibly be a
> configuration issue 
> on my end, but I cannot seem to figure out what
> exactly is going on...
> 
>     At my office I have a Cisco 2620 router acting
> as the network 
> DHCP server. On said router, I have a mix of both
> static and dynamic 
> IP allocations. The relevant configuration is below:
> 
> no ip dhcp conflict logging
> ip dhcp excluded-address 172.16.208.1 172.16.208.100
> ip dhcp bootp ignore
> !
> ip dhcp pool 172.16.208.0/24
>     import all
>     network 172.16.208.0 255.255.255.0
>     default-router 172.16.208.1
>     dns-server 67.135.184.20 67.135.184.21
> !
> ip dhcp pool computer1
>     host 172.16.208.58 255.255.255.0
>     client-identifier 0100.0475.99fe.e7
> !
> ip dhcp pool billing
>     host 172.16.208.15 255.255.255.0
>     INSERT LINE HERE...
> !
> 
> The machine that is causing me grief is "billing".
> No matter what I 
> do, I cannot seem to get the router to recognize the
> 
> client-identifier that I specify. I have tried the
> following configs 
> to see if I could get anything to work...
> 
>     hardware-address 00d0.b7a9.26c2
>     hardware-address 0100.d0b7.a926.c2
>     client-name 00d0.b7a9.26c2
>     client-name 0100.d0b7.a926.c2
>     client-identifier 00d0.b7a9.26c2
>     client-identifier 0100.d0b7.a926.c2
>     client-name "billing"
> 
> I forget any other ones...
> 
> In the dhclient.conf file, I have tried specifying
> the 
> dhcp-client-identifier option to all the various
> iterations above. I 
> have also tried setting the host-name to the same
> values.
> 
> Here's what I'm seeing on the router:
> 
> 9w0d: DHCPD: checking for expired leases.
> 9w0d: DHCPD: DHCPREQUEST received from client
> 00d0.b7a9.26c2.
> 9w0d: DHCPD: Sending DHCPACK to client
> 00d0.b7a9.26c2 (172.16.208.129).
> 9w0d: DHCPD: child  pool: 172.16.208.0 /
> 255.255.255.0 (172.16.208.0/24)
> 9w0d: DHCPD: pool 172.16.208.0/24 has no parent.
> 9w0d: DHCPD: child  pool: 172.16.208.0 /
> 255.255.255.0 (172.16.208.0/24)
> 9w0d: DHCPD: pool 172.16.208.0/24 has no parent.
> 9w0d: DHCPD: child  pool: 172.16.208.0 /
> 255.255.255.0 (172.16.208.0/24)
> 9w0d: DHCPD: pool 172.16.208.0/24 has no parent.
> 9w0d: DHCPD: creating ARP entry (172.16.208.129,
> 00d0.b7a9.26c2).
> 9w0d: DHCPD: unicasting BOOTREPLY to client
> 00d0.b7a9.26c2 (172.16.208.129).
> 
> So, it assigns it the address 172.16.208.129,
> instead of the hard 
> coded 172.16.208.15.
> 
> The client-identifiers will not match with what I
> have tried on the 
> router as far as the client-identifier or
> client-name or 
> hardware-address lines...
> 
> I have contacted Cisco about it, because my gut
> instinct is that the 
> problem is on the router, not the dhclient. After
> working on it for a 
> couple weeks on and off with Cisco, they came to the
> conclusion that 
> they didn't know what was going on and couldnt fix
> it.
> 
> Oh, here's a sh ip dhcp bind
> 
> Bindings from all pools not associated with VRF:
> IP address          Client-ID/              Lease
> expiration        Type
>                      Hardware address/
>                      User name
> 172.16.208.3        0100.5004.d7c6.7c       Infinite
>                Manual
> 172.16.208.4        0100.104b.2b27.ca       Infinite
>                Manual
> 172.16.208.5        0100.0502.37e5.9f       Infinite
>                Manual
> 172.16.208.6        0100.e081.2e69.6a       Infinite
>                Manual
> 172.16.208.7        0100.0d60.11f4.89       Infinite
>                Manual
> 172.16.208.8        0010.5aaa.8c7c          Infinite
>                Manual
> 172.16.208.9        0100.9027.3a4c.55       Infinite
>                Manual
> 172.16.208.10       0100.0502.8e16.10       Infinite
>                Manual
> 172.16.208.11       0100.6097.bbfe.e6       Infinite
>                Manual
> 172.16.208.12       0010.4b21.5e02          Infinite
>                Manual
> 172.16.208.13       0100.3018.a5ea.1a       Infinite
>                Manual
> 172.16.208.14       0100.1485.1e82.85       Infinite
>                Manual
> 172.16.208.15       00d0.b7a9.26c2          Infinite
>                Manual
> 172.16.208.58       0100.0475.99fe.e7       Infinite
>                Manual
> 172.16.208.101      0050.04d7.c67c          May 03
> 1993 12:26 PM    Automatic
> 172.16.208.102      0100.c0b6.01b5.a3       May 03
> 1993 05:13 PM    Automatic
> 172.16.208.129      00d0.b7a9.26c2          May 03
> 1993 08:06 PM    Automatic
> 
> As you can see above, some of the Client-ID's have
> the 01 prepended, 
> and some do not... I cannot figure out why the
> router detects some of 
> then like that and others not. I know a
> Client-Identifier is partly a 
> microsoft invention, but even when I use the
> hardware-address 
> command, I cannot get dhclient to get the assigned
> address...
> 
> I was hoping that maybe someone out there has ran
> into this before 
> and can point me towards a solution or work-around.
> 
> 
> Thanks in advance,
> Brad
> 
> 
> -- 
> This message has been scanned for viruses and
> dangerous content by MailScanner, and is
> believed to be clean.
> 
> 
> 



		
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