Printer FriendlyEmail Article Link

Spirent TestCenter: What does the DHCP Server ID Override suboption do?

  • RFC 5107 - DHCP Server Identifier Override Suboption
The explanation in RFC 5107 (DHCP Server Identifier Override Suboption) describes the use case for why this suboption was created.
  • A relay agent (RA) wishing to have a client's RENEW DHCPREQUEST to come through the RA (versus possibly bypassing it by contacting the DHCP server directly) will insert the Server ID Override suboption with its address.
  • This informs the DHCP server that in its replies (DHCPOFFER, DHCPACK) to use in the Server ID option (option 54) the address specified in the Server ID Override suboption.
    • That is, the DHCP server will use the address from the Server ID Override in the DHCP Server Indentifier
    • Here's also what the RFC says:
           This DHCP relay agent suboption, Server Identifier Override, allows
           the relay agent to tell the DHCP server what value to place into the
           Server Identifier option [5].
  • The RA then passes this Server ID option back to the client.
  • So in subsequent RENEW DHCPREQUESTs, the client will contact the RA thereby allowing the RA to again insert other relevant information (e.g., Circuit ID, Remote ID)

Product : Access,DHCP