Skip navigation

"DHCP only" mode

3935 Views 3 Replies Latest reply: Jul 29, 2013 9:18 AM by Bob Timmons RSS
UKenGB Level 2 Level 2 (270 points)
Currently Being Moderated
Jul 29, 2013 5:54 AM

This question could apply to any Airport Extreme and is not about the meaning of DHCP or NAT etc, but the wording used by Apple in the configuration and what that might mean - specifically, what do they mean by "DHCP only"?

 

Bridged of course means no routing whatsoever and the 4 ethernet ports simply act as a 4 port switch. "DHCP and NAT" means full routing between the 3 LAN ports (and wireless) and the WAN port, using NAT and acting also as a DHCP server. But inbetween there is "DHCP only" and I'm trying to understand what that means - precisely.

 

I guess the important issue is whether there is any router functionality in this mode. There is when in "NAT and DHCP", but not when it's set to "Bridged only". However, I can find no information about whther there is or not when it's set to "DHCP only".

 

The reason I ask is that I want to use an Airport Extreme (gigabit) on a network to bridge the wired and wireless ethernet segments. "Bridged only" would work except I want it to also provide DHCP. But if "DHCP only" is selected, does it try to route between the WAN port and the LAN ports, or do I have 4 equivalent ports as per "Bridged only" mode?

 

The issue I have is that the network I am setting up has NO Internet access. Unbelievable as that may seem to some of you, networking is not all about Internet access and it should be possible to operate a DHCP server on a LAN with no functional router. Apple products like to insist on there being one, but they're wrong to insist that. So can I use an Aiport to do what I need? Anyone know whther routing functionality is disabled in "DHCP only" mode?

MacPro, MacBook Pro, Mini Server, ´ú┐TVs, iPad, iPhone 4, Mac OS X (10.7.2), 30" HD display
  • Bob Timmons Level 9 Level 9 (75,845 points)
    Currently Being Moderated
    Jul 29, 2013 6:36 AM (in response to UKenGB)
    what do they mean by "DHCP only"?

     

    This setting is rarely needed any more....and would be used only if your Internet Service Provider (ISP) or a separate DHCP server has supplied the AirPort with a bank of fixed or static IP addresses to use.

     

    But if "DHCP only" is selected, does it try to route between the WAN port and the LAN ports

    Yes

     

     

    The first fixed IP address would be used to setup the AirPort to connect using that Static IP address. Call that the WAN IP Address. The other remaining IP addresses would be provided by the AirPort to route to connected devices.

     

    So, let's say that a DHCP server was providing the following IP addresses that you wanted to use:

     

    80.192.168.33

    80.192.168.34

    80.192.168.35

    80.192.168.36

    80.192.168.37

    Etc.

     

    The first address,  80.192.168.33 would be used as a Static IP address for the AirPort to connect to the network

     

     

    Screen Shot 2013-07-29 at 8.14.03 AM.png

     

     

    Then, click the Network tab and select DHCP only and enter the range of IP addresses to be used. So the range would look something like 80.192.168.34 to 80.192.168.39 or higher depending on how many IP addresses the DHCP server was issuing.

     

     

    Screen Shot 2013-07-29 at 8.21.33 AM.png

     

    So can I use an Aiport to do what I need?

     

    I honestly don't know since I do not understand what you are trying to accomplish.

     

    Anyone know whther routing functionality is disabled in "DHCP only" mode?

    In "DHCP only" mode, the AirPort connects using the first fixed IP address that the server provides and it routes the other range of IP addresses to connected devices.  In effect, in "DHCP only" mode, the AirPort is a router that does not provide NAT service.

     

    I do not know if that is what you are looking for. But, if you do not want the AirPort to "route" anything.....you would use Bridge Mode. In that setting the AirPort acts like an unmanaged Ethernet switch with the exception that you could use it to set up wireless service if you needed that.

  • Bob Timmons Level 9 Level 9 (75,845 points)
    Currently Being Moderated
    Jul 29, 2013 9:18 AM (in response to UKenGB)

    OK, so in "DHCP only" mode routing is enabled.

     

    Yes. As I said, in "DHCP only" mode, the AirPort connects using the first fixed IP address that the server provides and it routes the other range of IP addresses to connected devices.  In effect, in "DHCP only" mode, the AirPort is a router that does not provide NAT service.

     

    I wish Apple would make their documentation more complete.

    You might want to let Apple know.

     

    Apple - AirPort Extreme - Feedback

Actions

More Like This

  • Retrieving data ...

Bookmarked By (0)

Legend

  • This solved my question - 10 points
  • This helped me - 5 points
This site contains user submitted content, comments and opinions and is for informational purposes only. Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site. All postings and use of the content on this site are subject to the Apple Support Communities Terms of Use.