Junos OS

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EX dhcp relay and pxe boot issue.

  • 1.  EX dhcp relay and pxe boot issue.

    Posted 10-12-2020 06:54

    Hello,
    Facing issue with DHCP relay on Ex4200.
    DHCP server located in Location A

    Servers located in Location B and each server has different vlan.
    When we boot server using pxe booting..  relay serve via different ip configured on interfaces even we make vlan primary/preferred it does not work.

    Any idea how to fix it once and for all.
    Thanks

     

     



  • 2.  Re: EX dhcp relay and pxe boot issue.

    Posted 10-12-2020 21:18

    I think you need support for unnumbered address, but is not supported on EX series



  • 3.  Re: EX dhcp relay and pxe boot issue.

     
    Posted 10-13-2020 05:57

    Could you share the following information

    • current dhcp forwarding configuration
    • vlan(s) that you want forwarding for
    • destination address of the dhcp server
    • route table showing where that address will be forwarded
    • Local addresses on the ex4200 vlan.x and lo0.x
    • Confirmation that the dhcp server has a valid return route to the ex address

     



  • 4.  Re: EX dhcp relay and pxe boot issue.

    Posted 10-13-2020 11:12

    Hello,
    It is a very simple setup.
    Location A: dhcp server ip 196.168.0.10

    Location B: server connected to vlan xx need to be pxe booting.
    config:  set forwarding-options helpers bootp interface vlan.xx server 192.168.0.10 routing-instance vrf1

    Network shows : vrf1.inet.0
    server is on vlan.xx interface ip 196.168.10.9/29
    switch has me0 configured as 10.0.0.10

    When pxe boot process starts dhcp server get reply from me0 address.
    In other setup dhcp server get reply from linknet ip.

    No matter even if I set 196.168.10.9/29  primary / preferred it won't  serve the purpose.

    Thanks



  • 5.  Re: EX dhcp relay and pxe boot issue.

     
    Posted 10-14-2020 02:39

    The config is choosing me0 as the source towards the dhcp server for some reason. We need to dig into your routing tables and paths since your end nodes are in a routing instance.  Can you confirm the instance type?

     

    Are you leaking routes in some way?

     

    Is the dhcp server route reachable directly in the vrf1.inet.0 table?

     

    Is the ex4200 address vlan.x placed into vrf1?

     

     



  • 6.  Re: EX dhcp relay and pxe boot issue.

    Posted 10-14-2020 11:18

    First time we booted server everything was perfect as it should be but after that all requests are going via me0.
    Tired location C with same DHCP server now in this location link net ip is source towards DHCP.

    Instance vrf layer3.

    Are you leaking routes in some way?
    Nope
    Is the dhcp server route reachable directly in the vrf1.inet.0 table?
    Yes
    Is the ex4200 address vlan.x placed into vrf1?
    Yes