Cisco Router DHCP address reservation for device with Repeater

[onlize111]

Hello,

This is my configuration. Cisco Router -> AP -> Repeater -> Device.

I am trying to configure DHCP, so this device would use reserved IP address. This is my configuration:

ip dhcp excluded-address 192.168.100.1 192.168.100.100
ip dhcp excluded-address 192.168.100.200 192.168.100.255
!
ip dhcp pool StaticDevice
   host 192.168.100.200 255.255.255.0
   client-identifier abcd.ef98.ba7e
!
ip dhcp pool CLIENT
   import all
   network 192.168.100.0 255.255.255.0
   default-router 192.168.100.1
   dns-server 8.8.8.8 8.8.4.4
   lease 0 1

After I restarted device, I have the following:

Router#show ip dhcp binding
Bindings from all pools not associated with VRF:
IP address          Client-ID/              Lease expiration        Type
                    Hardware address/
                    User name
192.168.100.102       abcd.ef98.ba7e          Apr 07 2014 11:20 AM    Automatic
192.168.100.200       abcd.ef98.ba7e          Infinite                Manual
Router#
 

If I try hardware-address instead of client-identifier, this device does not receive any DHCP address. I waited for about 15-20 minutes and no address assigned at all.

I think the problem is that I am using repeater. My AP shows me that the DHCP request comes from repeater's MAC address. I cannot use repeater's MAC address because there are few more devices use that repeater, but I need DHCP reservation only for this one.

Can someone help me with this problem?

[acampbell]

i,

Can you try re-configuring your reservation:-

!
ip dhcp pool StaticDevice
   host 192.168.100.200 255.255.255.0
   client-identifier 01ab.cdef.98ba.7e
!

You need to prefix the mac address with 01

see this link :-
http://www.cisco.com/c/en/us/td/docs/ios/12_2/ip/configuration/guide/fipr_c/1cfdhcp.html#wp1001108

Hope this helps
Regards
Alex

[onlize111]

Thank you for your reply. I tried it. Actually, I have it in my config right now. I did not show it here. I have:

ip dhcp pool StaticDevice
   host 192.168.100.200 255.255.255.0
   client-identifier abcd.ef98.ba7e
!
ip dhcp pool StaticDevice2
   host 192.168.100.201 255.255.255.0
   client-identifier 01ab.cdef.98ba.7e
!

Router#show ip dhcp binding
Bindings from all pools not associated with VRF:
IP address          Client-ID/              Lease expiration        Type
                    Hardware address/
                    User name
192.168.100.102       abcd.ef98.ba7e          Apr 07 2014 11:20 AM    Automatic
192.168.100.200       abcd.ef98.ba7e          Infinite                Manual
192.168.100.201       01ab.cdef.98ba.7e     Infinite                Manual
Router#
 

It does not want to take it.

Any ideas?

[Julio Carvajal]

Hello,

Can you run the following debugs

-debug ip dhcp server packet

So you can see on the router itself the value he is reciving and then you can confirm whether you are configuring right or not?

Regards

Jcarvaja

[onlize111]

Thank you for your reply. I do not know Cisco that good, so please tell me what else should I do. It does not show me anything when I run this command:

Router#debug ip dhcp server packet
DHCP server packet debugging is on.
Router#
 

And nothing after that.

[Julio Carvajal]

Hello,

That's the command right there, u did good.

Are you connected via console (If yes, avoid step1)

Step 1 (If SSH,Telnet access)

Now add the command 

terminal monitor

Step 2 

Renew the IP address on the Repeater and look in the output for a message such as 

DHCPD:DHCPDISCOVER received from client 0b07.1134.a029

Regards

[onlize111]

Thank you for your reply. These are the entries related to that device that I have:

Apr  7 22:05:03: DHCPD: DHCPDISCOVER received from client abcd.ef98.ba7e on interface Ethernet0.
Apr  7 22:05:05: DHCPD: Sending DHCPOFFER to client abcd.ef98.ba7e (192.168.100.115).
Apr  7 22:05:05: DHCPD: broadcasting BOOTREPLY to client abcd.ef98.ba7e.
Apr  7 22:05:06: DHCPD: DHCPREQUEST received from client abcd.ef98.ba7e.
Apr  7 22:05:06: DHCPD: broadcasting BOOTREPLY to client abcd.ef98.ba7e.
 

It looks that it receives correct MAC address. Why wouldn't it assign address that I need?

[Julio Carvajal]

Hey,

It's my pleasure to help sr :) Just remember to rate my posts with the 5 stars at the bottom of each reply. That's like a thanks for us the Geek People :)

Now, great tshoot done, We now confirm we are receiving the right Client ID information on the DHCP Discovery packet.

Can you change one of the DHCP exclude lines to look like

ip dhcp excluded-address 192.168.100.201 192.168.100.255

Then try to renew and let me know :) If this does not work I will recreate it real quick, Just let me know how it goes 

[onlize111]

This what I got:

Apr  7 22:24:49: DHCPD: DHCPDISCOVER received from client abcd.ef98.ba7e on interface Ethernet0.
Apr  7 22:24:49: DHCPD: Allocate an address without class information (192.168.100.0)
Apr  7 22:24:51: DHCPD: Sending DHCPOFFER to client abcd.ef98.ba7e (192.168.100.116).
Apr  7 22:24:51: DHCPD: broadcasting BOOTREPLY to client abcd.ef98.ba7e.
Apr  7 22:24:51: DHCPD: DHCPREQUEST received from client abcd.ef98.ba7e.
Apr  7 22:24:51: DHCPD: Can't find any hostname to update
Apr  7 22:24:51: DHCPD: Sending DHCPACK to client abcd.ef98.ba7e (192.168.100.116).
Apr  7 22:24:51: DHCPD: broadcasting BOOTREPLY to client abcd.ef98.ba7e.

[Julio Carvajal]

So no kudos to me yet, Come on hehehe.

Now I build a Quick GNS lab just to show you how this should look like

You can take a look at the DHCP Lab Attachment.

Now, here is the config on R1

interface Ethernet0
 ip address 192.168.1.1 255.255.255.0

ip dhcp pool All_LAN
   network 192.168.1.0 255.255.255.0
   default-router 192.168.1.1
   dns-server 8.8.8.8
ip dhcp pool Only_R2
   host 192.168.1.200 255.255.255.0

I still do not know the client ID of R2 so have not add it yet.

Then the r2-r3 config

interface Ethernet0
 ip address dhcp

Now I ran the debug I asked you to run and Got:

R1#debug ip dhcp server packet
DHCP server packet debugging is on.

*Mar  1 00:03:11.663: DHCPD: DHCPDISCOVER received from client 0063.6973.636f.2d64.3030.332e.3132.3538.2e30.3030.312d.4574.30 on interface Ethernet0.
*Mar  1 00:03:11.663: DHCPD: Allocate an address without class information (192.168.1.0)
R1#

Afterwards I modify config as follows

ip dhcp pool Only_R2
   host 192.168.1.200 255.255.255.0
   client-identifier 0063.6973.636f.2d64.3030.332e.3132.3538.2e30.3030.312d.4574.30

Went to R2 shut/no shut and voila!

R2(config-if)#shut
*Mar  1 00:03:29.031: %LINK-5-CHANGED: Interface Ethernet0, changed state to administratively down
*Mar  1 00:03:30.031: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0, changed state to down
R2(config-if)#no shut
R2(config-if)#
*Mar  1 00:03:41.407: %LINK-3-UPDOWN: Interface Ethernet0, changed state to up
*Mar  1 00:03:42.407: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0, changed state to up
R2(config-if)#
*Mar  1 00:03:43.779: %DHCP-6-ADDRESS_ASSIGN: Interface Ethernet0 assigned DHCP address 192.168.1.200, mask 255.255.255.0, hostname R2

R2#sh ip interface  brief
Interface                  IP-Address      OK? Method Status                Protocol
Ethernet0                  192.168.1.200   YES DHCP   up                    up

The output on the DHCP server looked as follows:

*Mar  1 00:04:29.507: DHCPD: DHCPDISCOVER received from client 0063.6973.636f.2d64.3030.332e.3132.3538.2e30.3030.312d.4574.30 on interface Ethernet0.
*Mar  1 00:04:29.507: DHCPD: Sending DHCPOFFER to client 0063.6973.636f.2d64.3030.332e.3132.3538.2e30.3030.312d.4574.30 (192.168.1.200).
*Mar  1 00:04:29.511: DHCPD: broadcasting BOOTREPLY to client d003.1258.0001.
*Mar  1 00:04:29.643: DHCPD: DHCPREQUEST received from client 0063.6973.636f.2d64.3030.332e.3132.3538.2e30.3030.312d.4574.30.
*Mar  1 00:04:29.647: DHCPD: No default domain to append - abort update
R1#
*Mar  1 00:04:29.647: DHCPD: Sending DHCPACK to client 0063.6973.636f.2d64.3030.332e.3132.3538.2e30.3030.312d.4574.30 (192.168.1.200).
*Mar  1 00:04:29.647: DHCPD: broadcasting BOOTREPLY to client d003.1258.0001.

Try to do the same and get back with the result

Regards,

[onlize111]

Thank you for your help. I found a way around the problem. I configured IP address through repeater. Not sure if it will be okay, so I will test it later.

Thank you.

[Julio Carvajal]

OK