DHCP problem !

Answered Question
Jun 4th, 2008
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Hello,


I have a 1812 cisco router, I have 2 vlans (172.31.0.0/24 and 172.31.2.0/24) and I configured this :

ip dhcp pool dhcp-vlan2

import all

network 172.31.0.0 255.255.255.0

domain-name domain1.com

dns-server x.x.x.x

default-router 172.31.0.1

lease infinite

!

ip dhcp pool dhcp-vlan3

import all

network 172.31.2.0 255.255.255.0

domain-name domain2.com

dns-server x.x.x.x

default-router 172.31.2.1

lease infinite


ip dhcp pool name1

host 172.31.2.20

hardware-address 01ab.cdef.ghij.kl

client-name name2


The problem is that this manual binding in the end is not working; the host with that MAC gets another IP everytime I renew the dhcp request.

Before setting this manual binding I had that host setup staticly with that IP.


Where is the problem?


Correct Answer by Richard Burts about 8 years 11 months ago

Spinu


Try using the client-identifier instead of the hardware-address command.


I found this is the command reference:

Microsoft DHCP clients require client identifiers instead of hardware addresses. The client identifier is formed by concatenating the media type and the MAC address. For example, the Microsoft client identifier for Ethernet address b708.1388.f166 is 01b7.0813.88f1.66, where 01 represents the Ethernet media type. For a list of media type codes, refer to the "Address Resolution Protocol Parameters" section of RFC 1700, Assigned Numbers.

Examples


The following example specifies the client identifier for Mac address b7.0813.8811.66 in dotted-hexadecimal notation:


client-identifier 01b7.0813.8811.66


If you want more detail you can start with this link:

http://www.cisco.com/en/US/docs/ios/12_1/iproute/command/reference/1rddhcp.html#wp1017792


HTH


Rick


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Correct Answer
Richard Burts Wed, 06/04/2008 - 04:25
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Spinu


Try using the client-identifier instead of the hardware-address command.


I found this is the command reference:

Microsoft DHCP clients require client identifiers instead of hardware addresses. The client identifier is formed by concatenating the media type and the MAC address. For example, the Microsoft client identifier for Ethernet address b708.1388.f166 is 01b7.0813.88f1.66, where 01 represents the Ethernet media type. For a list of media type codes, refer to the "Address Resolution Protocol Parameters" section of RFC 1700, Assigned Numbers.

Examples


The following example specifies the client identifier for Mac address b7.0813.8811.66 in dotted-hexadecimal notation:


client-identifier 01b7.0813.8811.66


If you want more detail you can start with this link:

http://www.cisco.com/en/US/docs/ios/12_1/iproute/command/reference/1rddhcp.html#wp1017792


HTH


Rick


Richard Burts Wed, 06/04/2008 - 09:56
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Spinu


I am glad that you got it worked out and that my suggestion was helpful. I find that sometimes the Cisco documentation is very good about telling you how to configure a particular function (hardware-address and client-identifier) and not so good at helping distinguish when you use one and when you use the other.


Thank you for using the rating system to indicate that your problem was resolved (and thanks for the rating). It makes the forum more useful when people can read a problem and can know that there were responses which did resolve the problem.


The forum is an excellent place to learn about Cisco networking. I encourage you to continue your participation in the forum.


HTH


Rick

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