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Latest post 08-17-2012 8:07 PM by qqabdal. 1 replies.
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  • 08-17-2012 12:31 AM

    DHCP snooping not working



    I am doing section number 7.4 of INE workbook Volume1 of dhcp snooping where DHCP server is R3 & R1 is dhcp client I configured SW1 with the following commands

    Rack1SW1#sh run | incl dhcp
    ip dhcp snooping vlan 13
    ip dhcp snooping database flash:/dhcp-bindings.txt
    ip dhcp snooping database write-delay 15
    ip dhcp snooping
     ip dhcp snooping limit rate 10
     ip dhcp snooping trust

    Outputs are below


    Rack1SW1#sh ip dhcp snooping
    Switch DHCP snooping is enabled
    DHCP snooping is configured on following VLANs:
    DHCP snooping is operational on following VLANs:
    DHCP snooping is configured on the following L3 Interfaces:

    Insertion of option 82 is enabled
       circuit-id format: vlan-mod-port
        remote-id format: MAC
    Option 82 on untrusted port is not allowed
    Verification of hwaddr field is enabled
    Verification of giaddr field is enabled
    DHCP snooping trust/rate is configured on the following Interfaces:

    Interface                    Trusted     Rate limit (pps)
    ------------------------     -------     ----------------
    FastEthernet0/1              no          10
    FastEthernet0/3              yes         unlimited

    Rack1SW1#sh ip dhcp snooping binding
    MacAddress          IpAddress        Lease(sec)  Type           VLAN  Interface
    ------------------  ---------------  ----------  -------------  ----  --------------------
    Total number of bindings: 0

    Rack1SW1#more flash:/dhcp-bindings.txt

    Please let me know where exactly the fault is so that I am able to achieve appropirate output

    • Post Points: 20
  • 08-17-2012 8:07 PM In reply to

    Re: DHCP snooping not working

    What issue are you facing? R1 not getting an IP Address? 

    If that's the problem, there are a several ways to fix it, but try to disable the insertion of option 82 on the switch with the following global config command:

    no ip dhcp snooping information option

    You may want to shutdown and no shutdown R1's interface afterwards to trigger a DHCP discover. Please let me know if it works for you.


    Good luck!

    • Post Points: 5
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