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dhcpd process is saturating the cpu

[ Edited ]
‎04-07-2017 04:56 AM

Hi All,

 

I have a switch which is acting as dhcp relay and since some day the process dhcpd is saturating the cpu. I can notice a peak from 10% to 99% in within one hour and now is keeping stay at 100%

Basically the config  is :

 

 forwarding-options helpers bootp interface

 

Model: ex3200-48t
JUNOS Base OS boot [12.3R6.6]

 

and cpu

 

  PID USERNAME         THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
 1266 root               1 132    0  9528K  4008K RUN     52.7H 68.51% dhcpd

 

helper statistics

 

BOOTP:
  Received packets: 47885191
  Forwarded packets: 68282073
  Dropped packets: 110
    Due to no interface in DHCP Relay database: 0
    Due to no matching routing instance: 0
    Due to an error during packet read: 0
    Due to an error during packet send: 20
    Due to invalid server address: 0
    Due to no valid local address: 90
    Due to no route to server/client: 0

 

Would you please suggest a starting point for investigationg the problem?

 

Thank you.

4 REPLIES 4
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Junos

Re: dhcpd process is saturating the cpu

‎04-08-2017 05:27 AM

This type of behavior feels like a bug.  So we search the PR database (problem reports).  And this appears to be the one you may be hitting

 

https://prsearch.juniper.net/InfoCenter/index?page=prcontent&id=PR1045693

 

You can upgrade to one of the fixed versions listed if this fits your case.

 

If you are not sure, you can open an official JTAC case and they should be able to verify if this is the bug you are seeing.

Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
http://puluka.com/home
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Re: dhcpd process is saturating the cpu

‎03-03-2020 09:40 AM

A temporary solution is to restart the DHCP process using ths command.  This will quickly restart the DHCP process and restore the CPU to a normal level. 

restart dhcp-service gracefully
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Re: dhcpd process is saturating the cpu

‎03-05-2020 02:05 PM

Hi FabNewCert

 

based on bootp stats, looks like the switch is receiving a lot of request,  have you tried to do monitor traffic interface <vlan.xyz>  no-resolve  matching "port 67 && 68" count 10 extensive? 

vlan.xyz is the vlan interface that is reachable to your dhcp server.

 

During the problem, ideally it would be better to use that command and see where the problem is coming from - with that capture, we will know who is requesting a lot of DHCP or maybe is stuck somehow.

 

Also, make sure, you don't have any interface of your EX trying to request dhcp , otherwise you might see this problem too

show configuration | display set | match dhcp

 

If this solves your problem, please mark this post as "Accepted Solution".

Regards, 

Franky

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Junos

Re: dhcpd process is saturating the cpu

‎03-12-2020 12:15 PM

Hi FabNewCert

 

Just checking to see if you were able to resolve the issue? if not, please let us and we can try to narrow down little bit more.

 

Thank you, 

Franky