Security Management

Expand all | Collapse all

What happens if using multi DHCP relay with same IP Pool?

Jump to Best Answer
  • 1.  What happens if using multi DHCP relay with same IP Pool?

    Posted 07-24-2017 03:01

    Hi all, 

    I'm confused when deploying with multi DHCP relay having the same DHCP pool
    .......................... ___________..................................
    Client 1 ====== |SRX/MX/EX |====== DHCP server 1
    Client 2 ====== |__________ | ====== DHCP server 2

    For example, I have 2 DHCP client are client 1 and client 2 connect to Junos device (SRX/MX/EX) and the Junos device connect to two DHCP server 1 and DHCP server 2 have same DHCP pool such as range: 192.168.1.10 to 192.168.1.100. 

    When Client 1 request DHCP supply IP, the client 1 send DHCP Discover packet, after that Juno's device relay to two DHCP server. Two DHCP server also send back DHCP information for client 1 are 192.168.1.10. Finally, Client 1 receives DHCP information from DHCP server 1 because it comes first. 
    After Client 1 request DHCP information successfully, the client 2 request. In this situation, DHCP information packet of DHCP server 2 comes first with IP address 192.168.1.10. 
    So the Junos device will drop the packet or transfer to Client 2? 


    Thank all, 🙂 



  • 2.  RE: What happens if using multi DHCP relay with same IP Pool?
    Best Answer

     
    Posted 07-25-2017 16:59

    The Juniper device will forward the packet.  There is no inspection of the response contents with DHCP forwarding just the forward and return of the request packets.

     

    When you use multiple servers you need to have them configured to be aware of each other if they are active active and serving the same pool.  The instructions for the specifics of this will be part of the DHCP server management software.