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DHCP option 82 relay: QFX switch does not insert client´s MAC address

  • 1.  DHCP option 82 relay: QFX switch does not insert client´s MAC address

    Posted 10-13-2020 13:15
      |   view attached

    Hello team:

    I am testing a QFX 5110 switch that I configured as a DHCP relay for PCs that request IPs to a DHCP server located one hop across this switch.

    I am interested in the switch inserting option 82.2 (DHCP Agent Remote ID, i.e. client´s MAC address) in the relayed DHCP requests, so I added the following JUNOS commands:

    {master:0}[edit forwarding-options dhcp-relay]
    root# show |display set
    set forwarding-options dhcp-relay relay-option-82 circuit-id no-vlan-interface-name
    set forwarding-options dhcp-relay relay-option-82 circuit-id keep-incoming-circuit-id
    set forwarding-options dhcp-relay relay-option-82 remote-id no-vlan-interface-name
    set forwarding-options dhcp-relay relay-option-82 remote-id keep-incoming-remote-id
    set forwarding-options dhcp-relay server-group 4-srvs 10.1.1.2
    set forwarding-options dhcp-relay group 4 active-server-group 4-srvs
    set forwarding-options dhcp-relay group 4 interface ge-0/0/1.0

     

    But no matter which combinations I choose in this config area, my sniffer always shows me that the "remote-id" field in the DHCP relayed packet has exactly the same value as in the "circuit-id" field. It seems that the switch does not pick the MAC address from the client to insert its value in the "remote-id" field of the relayed DHCP packet.

     

    ¿ Any ideas of what I could be doing wrong?

     

    Just in case I am attaching a snapshow of the wireshark capture in which I see that both the circuit-id and the remote-id fields are exactly the same.

     

    Thanks!



  • 2.  Re: DHCP option 82 relay: QFX switch does not insert client´s MAC address

    Posted 10-13-2020 13:36

    Just in case I shrinked my commands to the following set, but nothing really changed. The remote-ID field in the DHCP relayed packet does not contain the client´s MAC address.

     

    {master:0}[edit forwarding-options dhcp-relay]
    root# show |display set
    set forwarding-options dhcp-relay relay-option-82 remote-id
    set forwarding-options dhcp-relay server-group 4-srvs 10.1.1.2
    set forwarding-options dhcp-relay group 4 active-server-group 4-srvs
    set forwarding-options dhcp-relay group 4 interface ge-0/0/1.0



  • 3.  Re: DHCP option 82 relay: QFX switch does not insert client´s MAC address

    Posted 28 days ago

    Just asking.. The qfx acting the layer 3 "helper" for the devices connected to your system do you have a vlan option option 82 setup for it  ?

    I only ask as I have had things not work the way I expected as I have setup the Vlan fwd option 82 stuff but also the layer 3 fwd dhcp-relay  for the same vlan being supported by the irb ..

    set vlans Group4 l3-interface irb.999;

    set vlans Group4 forwarding-options dhcp-security option-82 circuit-id use-vlan-id
    set vlans Group4 forwarding-options dhcp-security option-82 remote-id host-name

    Yours.

    set forwarding-options dhcp-relay relay-option-82 remote-id
    set forwarding-options dhcp-relay server-group 4-srvs 10.1.1.2
    set forwarding-options dhcp-relay group 4 active-server-group 4-srvs
    set forwarding-options dhcp-relay group 4 interface ge-0/0/1.0