Problem obtaining IP from a cisco router

Jeremy Bessee jeremy.bessee at gcmail.maricopa.edu
Thu Feb 8 18:48:08 UTC 2007


Brad,

I just ran through your configuration on a 2611XM, IOS version 
12.2(15)T16, and it ran flawlessly.  The only thing I am not able to 
test is Linux.  Our labs are purely Windows XP.

Sincerely,


Jeremy

Brad Stockdale 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
>
>
>  
>


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