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DHCP relay on EX4300

  • 1.  DHCP relay on EX4300

    Posted 02-20-2019 03:19

    Hi 

    I 've configured DHCP relay on EX4300 but DHCP message is not be forwarded to DHCP server. 

    Here is my configuration.

     

    set forwarding-options dhcp-relay server-group CP 10.1.2.99
    set forwarding-options dhcp-relay server-group CP 10.1.3.254
    set forwarding-options dhcp-relay active-server-group CP
    set forwarding-options dhcp-relay group server active-server-group CP
    set forwarding-options dhcp-relay group server interface irb.27 < VLAN27 = Client' vlan

     

     

    root# run show dhcp relay statistics
    Packets dropped:
    Total 0

    Messages received:
    BOOTREQUEST 309
    DHCPDECLINE 0
    DHCPDISCOVER 309
    DHCPINFORM 0
    DHCPRELEASE 0
    DHCPREQUEST 0
    DHCPLEASEACTIVE 0
    DHCPLEASEUNASSIGNED 0
    DHCPLEASEUNKNOWN 0
    DHCPLEASEQUERYDONE 0

    Messages sent:
    BOOTREPLY 0
    DHCPOFFER 0
    DHCPACK 0
    DHCPNAK 0
    DHCPFORCERENEW 0
    DHCPLEASEQUERY 0
    DHCPBULKLEASEQUERY 0



  • 2.  RE: DHCP relay on EX4300

    Posted 02-20-2019 03:35

    Hello,

    Please check Your lo0.0 filter to allow udp ports 67,68 

    Thanks

    Alex



  • 3.  RE: DHCP relay on EX4300

     
    Posted 02-20-2019 04:17

     Hi Halo,

     

    Also, we can check  this output to see the BOOTP requests sent out to server and BOOTP replies received:

    monitor traffic interface <egress_interface_towards_server> no-resolve extensive

     

    In some cases, if the server responds with a non-standard source-port (anything other than udp 67), BOOTP replies will be dropped.  And you may need to enable this knob (available from Junos 14.1X53-D12.4 or 14.1X53-D30 and above)
    set system processes dhcp-service accept-any-source-port

     

    Hope this helps.

     

    Regards,
    -r.

    --------------------------------------------------

    If this solves your problem, please mark this post as "Accepted Solution."
    Kudos are always appreciated :).

     



  • 4.  RE: DHCP relay on EX4300

    Posted 02-20-2019 21:32

    There's no frewall filter on lo0.0. Interface irb.27 can ping to DHCP server.

    I saw this message when I capture packet on egress

     

    Capture.PNG

     

     



  • 5.  RE: DHCP relay on EX4300

     
    Posted 02-21-2019 00:56

    Hi Halo,

     

    Please note that the command to capture packets on egress is:

    monitor traffic interface <egress_interface_towards_server> no-resolve extensive

     

    The knob that to accept any source that we were looking at, is hidden, so please continue typing it in and commit:

    set system processes dhcp-service accept-any-source-port

     

    See https://prsearch.juniper.net/InfoCenter/index?page=prcontent&id=PR1070989 

     

    Hope this helps.

     

    Regards,
    -r.

    --------------------------------------------------

    If this solves your problem, please mark this post as "Accepted Solution."
    Kudos are always appreciated :).

     



  • 6.  RE: DHCP relay on EX4300

    Posted 02-20-2019 04:45

    Hey,

    check if dhcp server is reacbable from irb.27 with source ping.