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DHCP Addresses stop being offered to wireless clients on a ISA 550

                  In the past 2 weeks, 2x i have had to reboot the ISA 550 as clients were not offered ip addresses anymore.

There is 100 ip addresses to the default vlan. - 192.168.75 100 thru 192.168.75-200.  There are about 39 clients connected wirelessly on the default vlan when this happens.  Memory usage is about 60%, cpu uage in the 5 to 10% range. Power Cycle the router and they start to get ip addresses after power cycle is completed.  When I reboot the router memory usage is about 40%, cpu usage - 5%, although granted their are about 17 clients connected.

Have one Cisco WAP121 connected to an interface on the ISA 550.  The WAP offers a different ssid. Both the ISA 550 and WAP121 fails to offer dhcp ip addresses when the problem occurs.  No wired clients are ever connected.  The appliance is connected to a Cisco 3560 switch for dual redundant wan interfaces connected to 2 different isp's

Was on firmeware 1.2.15, just upgraded to 1.2.18  hopefully this will resolve the issues?

This setup was working flawlessly for 7 months until 2 weeks ago.

13 REPLIES

Re: DHCP Addresses stop being offered to wireless clients on a I

Please see this similar post where the issue ended up being the switch.

https://supportforums.cisco.com/thread/2249429

As well, what do you mean that no physical connected clients? Also you mentioned a 3560 with dual Internet connections. Are the Internet connections terminated in the ISA or the 3560?

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Shawn Eftink CCNA/CCDA Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.
New Member

Re: DHCP Addresses stop being offered to wireless clients on a I

No wired clients only wireless.  The isa 550 is connected to c3560 for the wan interfaces.  Their is no other switch it is connected too.  Changing the switch does not apply in this case as the other case did mention the change of the intellilink switch solved the issue.

Re: DHCP Addresses stop being offered to wireless clients on a I

Michael,
I will admit that I'm a little confused on why the Internet connections are in the 3560 instead of running dual mode on the ISA and terminating them on it. But that's not the issue you raised.
So is the WAP and ISA both handing out DHCP and they both start failing and fixed with a reboot or is the ISA doing all the DHCP?

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Shawn Eftink CCNA/CCDA Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.
New Member

Re: DHCP Addresses stop being offered to wireless clients on a I

Wap doesnt hand out addresses.  ISA does.  Wap only extends network reach to a different part of building.ISa does the dhcp.  The ISA hasnt failed in 3 days albeit thurs. Was a holiday. It has been happening about once a week.

Re: DHCP Addresses stop being offered to wireless clients on a I

Is it possible to run one or more devices physically connected to see if the issue only applies to the wireless or both?

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Shawn Eftink CCNA/CCDA Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.
New Member

Re: DHCP Addresses stop being offered to wireless clients on a I

No addresses are supplied by the isa.  That is the source.  Wap is only an extender with a separate isa.

Re: DHCP Addresses stop being offered to wireless clients on a I

Michael,
I'm sorry. I'm confused. I don't understand what you meant by your last post. Please elaborate.

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Shawn Eftink CCNA/CCDA Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.
New Member

Re: DHCP Addresses stop being offered to wireless clients on a I

The wap is not configured for dhcp.  It passes a dhcp request to the isa 55o and the isa repies with an address to the wireless client.  The wap broadcasts a separate ssid.  I use it to extend the signal to a far point in the building where the isa is too weak to work.  The problem is the isa.

Re: DHCP Addresses stop being offered to wireless clients on a I

Michael,

Couple of "stabs in the dark".  Have you tried changing the port that the WAP is plugged into to a different port on the ISA to see if that helps?  As well, have you tried forcing the Speed and Duplex on the port the the WAP is plugged into to 100M/Full or Half as there might be an occassional duples mismatch issue as well?

One other question.  How far is the cable run between the ISA and the WAP?  If it's over 300' (100M), you will have occasional issues with connectivity.

http://en.wikipedia.org/wiki/Category_5_cable

Shawn Eftink
CCNA/CCDA

Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.

Shawn Eftink CCNA/CCDA Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.
New Member

Re: DHCP Addresses stop being offered to wireless clients on a I

It is plugged into a wan that is fixed at 100 mbs full duplex.  The problem is not with the wap.  It is with the ISA DHCP Database.  I am not going to changed the wap. That is the wrong focus.  The run for the cat5 is about 125 feet.

Re: DHCP Addresses stop being offered to wireless clients on a I

I'm not suggesting that there is an issue with the WAP.  I'm suggesting a possible intermittent connectivity issue between the ISA and WAP.  Connecting the WAP to a different port on the ISA would suggest a possible flaky port on the ISA.  Additionally, a duplex mismatch could be caused by either the WAP or ISA, if that turned out to be the issue.  Obviously the cable run at 125' is not an issue.

Another question I have is have you determined whether the AP integrated into the ISA also stops handing out DHCP at the same time the WAP does?  Again, not suggesting it's a WAP issue, just trying to narrow down where the issue is.  Additionally, have you seen any errors in the ISA logs related to DHCP?

Shawn Eftink
CCNA/CCDA

Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.

Shawn Eftink CCNA/CCDA Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.
New Member

Re: DHCP Addresses stop being offered to wireless clients on a I

the wap connection connects but waits for an ip address which never comes.    The same thing as the ISA.  Both devices are affected by the ISA's inability to provide an ip address.

Re: DHCP Addresses stop being offered to wireless clients on a I

I just looked over the release notes for 1.2.15, 1.2.17, and 1.2.18.  I'm not seeing anything related to the DHCP issues you're having.  At this point, I'd recommend one of two courses of action.

  1. Factory reset the device - The thought behind this is that the original image install may have had a bug that would be corrected on a factory reset.
  2. Contacting Small Business Support (www.cisco.com/go/sbsc).  They will have tools they can use to better troubleshoot the issue and possibly remedy it.

I'm sorry I couldn't assist you further.

Shawn Eftink
CCNA/CCDA

Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.

Shawn Eftink CCNA/CCDA Please rate all helpful posts and mark correct answers to assist others searching for solutions in the community.
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