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Complete IP pool is marked as conflicting on DHCP request

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  • 1.  Complete IP pool is marked as conflicting on DHCP request

    Posted Sep 14, 2018 11:35 AM

     I am setting up a DHCP server running on one of MSR3012 interfaces:

     

    >display interface GigabitEthernet 0/1 brief 
    ...
    Interface Link Protocol Primary IP Description 
    GE0/1 UP UP 192.168.202.1 Workstations
    
    >display dhcp server pool 
    ...
    Network: 192.168.202.0 mask 255.255.255.0 
    address range 192.168.202.100 to 192.168.202.200
    expired 1 0 0 0
    gateway-list 192.168.202.1

     

    I don't see any problem here, but when an actual DHCP request comes in the router marks all of the IPs in the pool as conflicting:

    *Sep 14 23:16:09:005 2018 Main router DHCPS/7/PACKET: 
    From 0.0.0.0 port 68, interface GigabitEthernet0/1
    Message type: REQUEST (1)
    Hardware type: 1, Hardware address length: 6
    Hops: 0, Transaction ID: 1891928330
    Seconds: 0, Broadcast flag: 0
    Client IP address: 0.0.0.0 Your IP address: 0.0.0.0
    Server IP address: 0.0.0.0 Relay agent IP address: 0.0.0.0
    Client hardware address: <stripped>
    Server host name: not configured
    Boot file name: not configured
    DHCP message type: DHCPDISCOVER (1)
    *Sep 14 23:16:09:005 2018 Main router DHCPS/7/EVENT: Receive a DHCPDISCOVER message from GigabitEthernet0/1.
    *Sep 14 23:16:09:005 2018 Main router DHCPS/7/EVENT: Add a conflict IP 192.168.202.100.
    *Sep 14 23:16:09:005 2018 Main router DHCPS/7/EVENT: Add a conflict IP 192.168.202.101.
    *Sep 14 23:16:09:005 2018 Main router DHCPS/7/EVENT: Add a conflict IP 192.168.202.102.
    *Sep 14 23:16:09:005 2018 Main router DHCPS/7/EVENT: Add a conflict IP 192.168.202.103.
    *Sep 14 23:16:09:006 2018 Main router DHCPS/7/EVENT: Add a conflict IP 192.168.202.104.
    *Sep 14 23:16:09:006 2018 Main router DHCPS/7/EVENT: Add a conflict IP 192.168.202.105.
    *Sep 14 23:16:09:006 2018 Main router DHCPS/7/EVENT: Add a conflict IP 192.168.202.106.
    ...
    *Sep 14 23:16:09:006 2018 Main router DHCPS/7/EVENT: Add a conflict IP 192.168.202.200.

    After this DHCP server is not able to offer a lease to any clients. Any ideas why this could happen:?


    #DHCP


  • 2.  RE: Complete IP pool is marked as conflicting on DHCP request

    Posted Sep 15, 2018 08:38 AM

    Few more notes. I use the latest firmware, I can see all IPs as free in the pool before DHCP request arrives, the client is a single Ubuntu laptop connected directly to the router, it works fine with a static IP from the same subnet outside of the pool or with other DHCP servers. The problem is reproducible: if I reset IP conflicts all IPs become available and then are marked as conflicting simultaneously as soon as another DHCP request arrives.



  • 3.  RE: Complete IP pool is marked as conflicting on DHCP request

    EMPLOYEE
    Posted Sep 15, 2018 04:06 PM

    Hi,

    Could you please share the current configuration of the MSR Router, specially all DHCP configuration?

    Thank You!

    I am an HPE Employee



  • 4.  RE: Complete IP pool is marked as conflicting on DHCP request

    Posted Sep 16, 2018 12:51 PM

    Thank you for looking into it! I will post all the configuration ASAP. In the meantime, is there any particular command that can display complete DHCP configuration or I need to output all of it separately (IP pools, interfraces, DHCP server status, etc)?



  • 5.  RE: Complete IP pool is marked as conflicting on DHCP request

    EMPLOYEE
    Posted Sep 17, 2018 01:03 AM

    Hi,

    Try this 

    display current-configuration | include dhcp

    or

    display current-configuration begin dhcp

    if it will not work then share full.

     

    Thank You!

    I am an HPE Employee



  • 6.  RE: Complete IP pool is marked as conflicting on DHCP request

    Posted Sep 17, 2018 08:30 AM

    And thank you again!

    I found out what the problem was: misconfigured static NAT had IP pool that was overlapping with DHCP pool. The problem manifested in a rather strange way, but apparently DHCP assigned IP was indeed conflicting with IPs that router was supposed to use for NAT.