Problem with DHCP in Cisco 1100 Access Point

[elihcaros]

Hi all, please i need help,

I have installed an Aironet 1100 and i use it with dhcp, my configuration is the following:

ip dhcp excluded-address 172.28.13.1 172.28.13.149

ip dhcp excluded-address 172.28.13.155 172.28.13.254

!

ip dhcp pool prueba

network 172.28.13.0 255.255.255.0

default-router 172.28.13.30

dns-server 172.28.10.14

lease 10

!

it works well, but lately when a user tried to connected to the access point it gets ip:

169.254.155.137 255.255.0.0

i tried with a D-link DWL-650 802.11b card and with a Belking 54g Card and i have the same problem.

I solve this erasing the dhcp pool and then create it again, but this solve the problem just for a week and then the problem came back.

I hope you can help me. Thanks a lot for your time.

Atte,

Eli Caro

[chandlerbr]

You are allowing 5 addresses to be leased. Each lease is for 10 days. A sixth client cannot obtain a lease until the one of the first 5 expires. However, if one of the original clients is still active when it's lease expires, it will (or should) immediately request the same address again. The sixth client is still out of luck. It sounds like you require a pool greater than five. You could decrease the lease duration, increase the number of available addresses, or both. If you set the lease time to 8 hours (or one business day) the entire pool should be available again the next day. An 8-hour lease wouldn't be a good idea on a large network but should be fine for 5 addresses.

hth

Just a thought.

hth

[elihcaros]

Hi chandlerbr,

Well i think i wouldn't include the line

lease 10, in my configuration, i didn't especified a lease when my access point works fine, i include that because i think that maybe the aironet need a lease.

by the way, thanks a lot for your suggestion, any more ideas?

the weird thing is that the ip 169.254.155.137 is not in my config, why the users get that ip?

i don't know, please help.

thanks again for your time

atte,

Eli Caro

[chandlerbr]

The 169.254.x.x address is the result of Automatic Private IP Addressing (APIPA). By default, if a Microsoft client is configured for DHCP and it is unable to obtain an IP from a DHCP server, it will assign itself an address from the 169.254.0.0 -169.254.255.255 range. The concept is to reduce administration time. For example, you can configure all your MS clients on a LAN for DHCP without configuring a DHCP server, and the clients will all assign themselves IP addresses and can communicate via TCP/IP. Pretty slick if you think about it. This article talks about Windows Millennium Edition but it is the same for all MS products with TCP/IP installed.

http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/Q307/2/87.ASP&NoWebContent=1

I do believe you can disable APIPA with a registry hack if you want. Just search for APIPA and you'll find the hack.

Bottom line, if the DHCP server is accessible and addresses are available, you shouldn't see a 169.254.x.x address on the clients.

hth