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Thread: Cisco 877W debug question

  1. #1
    Junior Member
    Join Date
    Jun 2002

    Cisco 877W debug question

    Hi all,

    Not sure if this is the right forum but someone out there might know the answer here....

    I've got a Cisco 877 wireless router that I'm setting up for a client site and they require DHCP to be dished out over the wireless interface.

    I have an appropriate "ip helper" command on the wireless interface but I'm not seeing any udp traffic on any interfaces. I have a Windows 2003 server doing the DHCP (and I can see the DHCP broadcasts on this box with ethereal) but when i use the "debug ip udp" command on the router I see nothing?

    My question then is what is the best way to troubleshoot this problem? Which debug commands should I be using to see this traffic and confirm connectivity?

    I can ping the router from the server and the server from the router. The ACL's are wide open but I'm just not seeing any traffic?

    Any help would be appreciated.



  2. #2
    Senior Member
    Join Date
    Sep 2001
    Couple of things:
    -What version of IOS are you using?
    -Show us the config of your wireless interface
    -Are you receiving anything

    You could always do a debug ip packet (match on port 67 and port 68) to see if you're even receiving dhcp requests from clients and if they are being relayed.

    Also, don't forget to create the corresponding dhcp scope on your dhcp server.

    Credit travels up, blame travels down -- The Boss

  3. #3
    Junior Member
    Join Date
    Jun 2002
    Thanks for the reply ammo, unfortunately the device is at my other office so I can't get the IOS version easily although it is brand new so that should be up to date.

    I've got a copy of the config on file here though so here's the wireless bit:

    interface Dot11Radio0
    no ip address
    ip helper-address
    encryption mode ciphers tkip
    ssid ****-Wireless
    max-associations 50
    authentication open
    authentication key-management wpa
    wpa-psk ascii 0 ********Omitted***********
    speed basic-1.0 basic-2.0 basic-5.5 basic-6.0 basic-9.0 basic-11.0 basic-12.0 basic-18.0 basic-24.0 basic-36.0 basic-48.0 basic-54.0
    channel 2452
    station-role root
    no cdp enable
    bridge-group 1
    bridge-group 1 subscriber-loop-control
    bridge-group 1 spanning-disabled
    bridge-group 1 block-unknown-source
    no bridge-group 1 source-learning
    no bridge-group 1 unicast-flooding

    This is my first Cisco wireless product so most of the above config has been copied from other installations.

    Does that look right? Is there anything that should be added?

    The DHCP server ( has a scope of - 100 and its putting out address's OK (my laptop gets an address from it fine, just not via this router).


  4. #4
    Senior Member
    Join Date
    Mar 2004
    You don't need a helper address if you are on the same subnet.

  5. #5
    Senior Member
    Join Date
    Sep 2001
    Indeed, you are bridging, hence there is no need for the ip helper.
    Your dhcp server should handle your wifi clients in a normal fashion (broadcast dhcp without relay)...
    Credit travels up, blame travels down -- The Boss

  6. #6
    Junior Member
    Join Date
    Jun 2002

    dumb moment

    Hmmmm, for some reason I just assumed the Wifi interface would treat them differently. If that's just bridging then it should all just work?

    Looking more closely the dot11radio interface isn't assigned to any VLAN which is more likely to cause a problem.

    Thanks for the heads up guys.

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