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Complete IP pool is marked as conflicting on DHCP request

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graphite
Occasional Contributor

Complete IP pool is marked as conflicting on DHCP request

 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:?

5 REPLIES
graphite
Occasional Contributor

Re: Complete IP pool is marked as conflicting on DHCP request

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.

akg7
Frequent Advisor

Re: Complete IP pool is marked as conflicting on DHCP request

Hi,

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

Thank You!

I am an HPE Employee

graphite
Occasional Contributor

Re: Complete IP pool is marked as conflicting on DHCP request

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)?

akg7
Frequent Advisor

Re: Complete IP pool is marked as conflicting on DHCP request

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

graphite
Occasional Contributor
Solution

Re: Complete IP pool is marked as conflicting on DHCP request

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.