USG 1100 - DHCP issue - stops serving IP addresses

imaohw
imaohw Posts: 124  Ally Member
First Comment First Answer Friend Collector Sixth Anniversary
edited April 2021 in Security

I have a USG 1100 running v4.35 which is providing DHCP for the configured lans and vlans. Most of the devices on the lans and vlans are set up with IP/Mac binding so that they are always assigned the same IP address.

Periodically (4 times in the last 48 hours) the USG 1100 stops serving IP addresses. When this happens no devices on the lans or vlans can get an IP address.

This situation can be temporarily resolved by editing any DHCP parameter (I have not tried other non-DHCP parameters), such as pool size, in the ethernet or vlan configuration screen. Once the change is saved the USG 1100 starts serving IP addresses again.

This is a serious problem. When people enter our building they sometimes do not get an IP address. It is not until someone complains that we know there is an issue.

Happy to provide any configuration files or logs.

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All Replies

  • mMontana
    mMontana Posts: 1,389  Guru Member
    50 Answers 1000 Comments Friend Collector Fifth Anniversary

    How many addreses are provided by your USG1100?

    I intend the sum of all scopes of your network segments.

  • imaohw
    imaohw Posts: 124  Ally Member
    First Comment First Answer Friend Collector Sixth Anniversary
    edited October 2019

    @mMontana - across all scopes, about 175 address are in the IP/Mac binding tables which are provided by DHCP. An additional 30 or so addresses from 3 pools are handed out at any one time for guests.

  • Zyxel_Emily
    Zyxel_Emily Posts: 1,396  Zyxel Employee
    Zyxel Certified Network Administrator - Security Zyxel Certified Sales Associate 100 Answers 1000 Comments
    Hi @imaohw,
    When the issue happens, use the command debug system ps | match "dhc" on console to see if the daemon "dhcpd.leases" is working.

    If the daemon is working but clients cannot get IPs in a certain interface, capture the packets of the lan interface and check DHCP packets.

    Then go to MAINTENANCE > Diagnostics > Diagnostics > Collect and click "Collect Now".

    After the collection is done, go to MAINTENANCE > Diagnostics > Diagnostics > Files to download the diagnostic file and send the file to me in private message.

  • imaohw
    imaohw Posts: 124  Ally Member
    First Comment First Answer Friend Collector Sixth Anniversary

    @Zyxel_Emily - I sent you the requested info in a private message. If you need anything else please let me know.

    Thank you for your help.

  • Zyxel_Emily
    Zyxel_Emily Posts: 1,396  Zyxel Employee
    Zyxel Certified Network Administrator - Security Zyxel Certified Sales Associate 100 Answers 1000 Comments

    Hi @imaohw,

    The firmware is sent to you in private message.

    If the DHCP is not working, capture the packets of the lan interface and diagnostic file for analysis.

  • RobT
    RobT Posts: 8
    First Comment Friend Collector
    @Zyxel_Emily I'm experiencing a similar problem with my Zywall 110 where after about 3 days the DHCP server appears to stop working.  I ran the debug system command when the DHCP server was working and when it wasn't. Here's the output:

    Working:
    Router> debug system ps | match "dhc"
    14319     1 dhcpd           root     ?         19   0  0.0  0.1 Ss     8628  174                  8  1028  2157 17:37:42       09:49 00:00:00 /usr/sbin/dhcpd -lf /var/dhcp/dhcpd.                  leases -cf /var/zyxel/dhcpd.conf -q eth3 eth4 eth6 vlan4 vlan25 vlan100
    12160     1 dhcpcd_request  root     ?         19   0  0.0  0.0 Ss     2028   51                  6   364   507 17:37:24       10:07 00:00:00 /usr/local/sbin/dhcpcd_request eth1                   0 ZyWALL 110
    11681     1 dhcpcd_request  root     ?         19   0  0.0  0.0 Ss     2028   49                  2   364   507 17:36:50       10:41 00:00:00 /usr/local/sbin/dhcpcd_request eth0                   0 ZyWALL 110
    16053 12160 dhcpcd          root     ?         19   0  0.0  0.0 S      1836   36                  0   296   459 17:47:22       00:09 00:00:00 /sbin/dhcpcd -R -Y -N -B -G -L /var/                  zyxel/zysh/ -i ZyWALL 110 -h EBCzywall110 eth1
    11729     1 dhcpcd          root     ?         19   0  0.0  0.0 Ss     1836    6                  4   296   459 17:36:50       10:41 00:00:00 /sbin/dhcpcd -R -Y -N -B -G -L /var/                  zyxel/zysh/ -i ZyWALL 110 -h EBCzywall110 eth0

    Not Working:
    Router# debug system ps | match "dhc"
    11018     1 dhcpcd_request  root     ?         19   0  0.0  0.0 Ss     2028   516   364   507 08:52:51    01:54:57 00:00:06 /usr/local/sbin/dhcpcd_request eth0 0 ZyWALL 110
    11088     1 dhcpcd          root     ?         19   0  0.0  0.0 Ss     1836   492   296   459 08:53:03    01:54:45 00:00:00 /sbin/dhcpcd -R -Y -N -G -L /var/zyxel/zysh/ -i ZyWALL 110 -h EBCzywall110 eth0

    Any suggestions as to what is going on?



  • Zyxel_Kevin
    Zyxel_Kevin Posts: 885  Zyxel Employee
    Zyxel Certified Network Administrator - Security Zyxel Certified Sales Associate 100 Answers 500 Comments
    edited May 2022
    Hi @RobT,
    Please Kindly provide your firmware version. If the firmware is not the latest.
    Please upgrade to the latest. Thanks
    Kevin
  • RobT
    RobT Posts: 8
    First Comment Friend Collector
    I confirmed that firmware version is 4.71(AAAA.0).



  • Zyxel_Kevin
    Zyxel_Kevin Posts: 885  Zyxel Employee
    Zyxel Certified Network Administrator - Security Zyxel Certified Sales Associate 100 Answers 500 Comments
    Hi @RobT
    Please find your Inbox, I've sent the weekly for you. Please install and test .
    Thanks
    Kevin
  • RobT
    RobT Posts: 8
    First Comment Friend Collector
    Hi @Zyxel_Kevin I installed the weekly update and I'm now testing it. I'll post the test results.

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