Getting Peer hold all free leases

Glenn Satchell glenn.satchell at uniq.com.au
Wed Aug 18 07:22:42 UTC 2021


Hi Kraishak

omapi is a bit of a black art. It only handles some specific and not 
well defined items.It's also towards the end of it's lifecycle, so very 
unlikely to get any new features added. It is being replaced by the new 
Kea dhcp server, so perhaps this might be worth investigating?

There are some notes at the bottom of the dhcpd(8) man page. It also 
refers to omapi(3) and dhcpctl(3) man pages but those are not installed 
on my system (ubuntu).

regards,

Glenn

On 2021-08-18 16:58, Kraishak Mahtha wrote:

> Hi Glenn,
> 
> I tried restarting dhcpd services but no luck, tried the way of moving 
> that specific subnet to standalone mode and restart dhcpd services on 
> both and then again changed subnet to failover mode, now it is ok
> But I have few concerns in doing so,
> If we have such problem with many subnets it will be a problematic and 
> just checking if we have any way like using OMAPI and sending the force 
> request to dhcp service to try rebalance without disturbing the 
> services
> 
> Thanks
> Kraishak
> 
> On Wed, Aug 18, 2021 at 11:46 AM Kraishak Mahtha 
> <kraishak.edu at gmail.com> wrote:
> Hi Glenn,
> 
> I tried checking with tcpdump command to make sure traffic is able to 
> communicate initially, But again as recommended I checked with telnet 
> command as well
> 
> From primary:
> ==========
> command used:  /usr/bin/telnet 192.168.56.178 647
> Trying 192.168.56.178...
> Connected to 192.168.56.178.
> Escape character is '^]'.
> 
> From failover
> =========
> /usr/bin/telnet 192.168.56.156 647
> Trying 192.168.56.156...
> Connected to 192.168.56.156.
> Escape character is '^]'.
> 
> I hope this means the ports are able to communicate each other, Please 
> correct me If I am wrong in understanding this output
> 
> I also tried checking netstat to check port status
> From Primary
> ===========
> netstat -tulpna | grep 647
> tcp        0      0 192.168.56.156:647 [1]      0.0.0.0:*               
> LISTEN      8599/dhcpd
> tcp        0      0 192.168.56.156:47907 [2]    192.168.56.178:647 [3]  
>     ESTABLISHED 8599/dhcpd
> 
> From Failover
> ==========
> netstat -tulpna | grep 647
> tcp        0      0 192.168.56.178:647 [3]      0.0.0.0:*               
> LISTEN      7574/dhcpd
> tcp        0      0 192.168.56.178:647 [3]      192.168.56.156:47907 
> [2]    ESTABLISHED 7574/dhcpd
> 
> not blocked by any firewalls
> 
> ------> I don't have a firewall setup between the servers
> 
> Could you post the failover clause from dhcpd.conf from both servers?
> 
> ----> yes I did shared already in the thread,
> 
> Failover section from primary config
> 
> =========================
> failover peer "peer-host" {
> primary;
> address 192.168.56.156;
> port 647;
> peer address 192.168.56.178;
> peer port 647;
> max-response-delay 30;
> max-unacked-updates 30;
> load balance max seconds 3;
> mclt 1800;
> split 128;
> }
> 
> Failover section from failover config
> ======================
> failover peer "peer-host" {
> secondary;
> address 192.168.56.178;
> port 647;
> peer address 192.168.56.156;
> peer port 647;
> max-response-delay 30;
> max-unacked-updates 30;
> load balance max seconds 3;
> }
> 
> On Wed, Aug 18, 2021 at 10:51 AM Kraishak Mahtha 
> <kraishak.edu at gmail.com> wrote:
> Question to ISC Team,
> 
> Can we manually send a request for the DHCP server from externally to 
> do the pool balance for a specific subnet? or sent a force parameter in 
> send request to balance specific subnet
> 
> Thanks
> Kraishak
> 
> On Tue, Aug 17, 2021 at 5:41 PM Kraishak Mahtha 
> <kraishak.edu at gmail.com> wrote:
> Hi,
> I am using ISC DHCP in primary and failover mode and I am getting issue 
> that clients are not getting leases and when I checked for the service 
> logs I see as
> Primary Logs:
> ==========
> Aug 17 17:15:48 dhcp1 dhcpd[12130]: balancing pool f6f5f0 
> 192.168.56.0/24 [4]  total 50  free 0  backup 0  lts 0  max-own (+/-)0
> Aug 17 17:15:48 dhcp1 dhcpd[12130]: balanced pool f6f5f0 
> 192.168.56.0/24 [4]  total 50  free 0  backup 0  lts 0  max-misbal 0
> Aug 17 17:15:48 dhcp1 dhcpd[12130]: peer peer-host: Got POOLREQ, 
> answering negatively!  Peer may be out of leases or database 
> inconsistent.
> 
> Failover Logs
> ==========
> Aug 17 17:14:48 dhcp2 dhcpd[1902]: balancing pool bf05b0 
> 192.168.56.0/24 [4]  total 50  free 50  backup 0  lts -25  max-own 
> (+/-)5  (requesting peer rebalance!)
> Aug 17 17:14:48 dhcp2 dhcpd[1902]: balanced pool bf05b0 192.168.56.0/24 
> [4]  total 50  free 50  backup 0  lts -25  max-misbal 8
> pool response: 0 leases
> 
> I tried searching the forums and many of them suggested that there 
> might be inconsistency between the configuration file and leases 
> database, I cross verified the configs they are good and regarding the 
> leases file can we manually do any operation to make them in sync ?
> 
> I tried checking the status of the primary and failover in the lease 
> file but they are in normal-normal, cat dhcpd.leases | egrep "my 
> state|partner state" | tail -2
> my state normal at 2 2021/08/17 16:41:09;
> partner state normal at 2 2021/08/17 17:01:17;
> 
> Has anyone faced a similar issue/Any suggestions of how to fix the 
> issue,
> Can we manually send requests for the DHCP service to do the pool 
> balance and sync the leases for that specific subnet ?
> 
> Any help/suggestion would be much appreciated
> Thanks
> Kraishak

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Links:
------
[1] http://192.168.56.156:647
[2] http://192.168.56.156:47907
[3] http://192.168.56.178:647
[4] http://192.168.56.0/24
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