Re: DHCP Manual Bindings

From: Marko Milivojevic <markom_at_ipexpert.com>
Date: Wed, 17 Nov 2010 17:58:38 +0000

Absolutely correct. Running "debug ip dhcp server events" on the
server will answer all doubts as to what the client identifier value
you are dealing with.

That said... I have one DHCP question. Does anyone know a
scenario/situation when using "hardware-address" inside host pool
actually does anything?

--
Marko Milivojevic - CCIE #18427
Senior Technical Instructor - IPexpert
FREE CCIE training: http://bit.ly/vLecture
Mailto: markom_at_ipexpert.com
Telephone: +1.810.326.1444
Web: http://www.ipexpert.com/
On Wed, Nov 17, 2010 at 17:29, Adel Abouchaev <adel_at_netmasterclass.net> wrote:
> B  B  B  B Marko and Tyson are absolutely correct here.
>
> B  B  B  B To add a bit to the message on how to approach this situation if you aren't sure why client ID or any other parameters aren't leading to a correct DHCP assignment, the debug for DHCP is quite talkative and usually answers any question within a minute. I have found it very useful during troubleshooting DHCP issues for many occasions.
>
> Cheers,
>
> Adel Abouchaev, CCIE# 12037, CISSP, MCSE
>
> Technical Support Engineer
> Netmasterclass LLC, Cisco Learning Partner
> RFC821: adel_at_netmasterclass.net
> E.164: +18886772669
> HTTP: www.netmasterclass.net
>
>
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Marko Milivojevic
> Sent: Wednesday, November 17, 2010 8:10 AM
> To: Tyson Scott
> Cc: Steven Blasiol; Cisco certification
> Subject: Re: DHCP Manual Bindings
>
> Just to follow-up on Tyson's reply. This will probably work if you set
> "ip address dhcl client-identifier Fa0/0" on R1. If not, after certain
> IOS release (12.4somethingortheother) client identifier option is set
> to something else (see previous discussion on OSL for details).
>
> When you set the client-identifier option to be derived from the
> interface MAC address, it will still not be the MAC address alone. The
> MAC address will be prefixed by media type, which for Ethernet is "01.
> Therefore, your client-id becomes 01<MAC_ADDRESS>". You need to move
> the dot around a bit.
>
> For MAC address c002.0594.0000, client identifier becomes
> 01c0.0205.9400.00 -> just as Tyson wrote below.
>
> --
> Marko Milivojevic - CCIE #18427
> Senior Technical Instructor - IPexpert
>
> FREE CCIE training: http://bit.ly/vLecture
>
> Mailto: markom_at_ipexpert.com
> Telephone: +1.810.326.1444
> Web: http://www.ipexpert.com/
>
> On Wed, Nov 17, 2010 at 00:22, Tyson Scott <tscott_at_ipexpert.com> wrote:
>> That is because that will never be your client-identifier.
>>
>> ip dhcp pool LABMANUAL
>> B B host 10.0.12.77 255.255.255.0
>> B B client-identifier 01c0.0205.9400.00
>>
>> When you get the IP address you should be able to notice in the output of
>> "show ip dhcp bind" what the client identifier is showing up for when it
>> isn't working for you.
>>
>> Please let me know if this doesn't work for you. B If it doesn't work please
>> provide the output of "show ip dhcp bind"
>>
>> Regards,
>>
>> Tyson Scott - CCIE #13513 R&S, Security, and SP
>> Managing Partner / Sr. Instructor - IPexpert, Inc.
>> Mailto: tscott_at_ipexpert.com
>>
>>
>> -----Original Message-----
>> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
>> Steven Blasiol
>> Sent: Tuesday, November 16, 2010 7:10 PM
>> To: Cisco certification
>> Subject: DHCP Manual Bindings
>>
>> I am having some problems in GNS3 setting manual ip address bindings. B Here
>> are the relevant configs:
>>
>> (DHCP Client)R1 Fa0/0-------------------Fa0/0R2 (DHCP Server)
>>
>> Router1
>>
>> interface FastEthernet0/0
>> ip address dhcp client-id FastEthernet0/0 hostname CCIELAB
>> duplex auto
>> speed auto
>>
>>
>> Router2
>>
>> no ip dhcp conflict logging
>> !
>> ip dhcp excluded-address 10.0.12.1 10.0.12.50
>> !
>> ip dhcp pool LABMANUAL
>> B B host 10.0.12.77 255.255.255.0
>> B B client-identifier c002.0594.0000 (MAC of R1 Fa0/0)
>> B B client-name CCIELAB
>> !
>> ip dhcp pool LABDYNAMIC
>> B B network 10.0.12.0 255.255.255.0
>> B B domain-name ccie.com
>> B B default-router 10.0.12.1
>>
>>
>> When I have it configured like this I keep getting an address from the
>> LABDYNAMIC pool. B I thought maybe you could have two pools so I removed the
>> DYNAMIC pool and I just don't get an address.
>>
>> i am obviously missing something and the documentation i have found so far
>> is not really helpful.
>>
>> Thanks in advance.
>> --
>> Steven M. Blasiol
>>
>>
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>
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Received on Wed Nov 17 2010 - 17:58:38 ART

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