[Pierre74]

Hi!

I finally made the move to ADSL. I got myself a Zyxel Prestige 650H modem with integrated 4-port hub. The built-in router uses DHCP to provide IP adresses to the connected devices.

To this hup I intend to connect both an iMac and an AirPort basestation.

What I am wondering about is the set-up of the BaseStation. I have the choice of setting it to bridge between AirPort and Ethernet. In which case the router assigns an IP to my iBook on the AirPort network.

I may also activate DHCP on the BaseStation. Then, I understand, the BaseStation gets its IP from the router, whereas my computer gets one assigned by the BaseStation.

I have yet to try the second set-up. The first one works fine.

Are there any reasons to prefer one set-up over the other?

TIA
Pierre

[ghporter]

Your Zyxel modem has an integrated router, not a hub-that really makes a difference. A hub simply congregates the signals from all the devices attached to it, and can slow down access when more than one machine is trying to connect outside the LAN. On the other hand, a router or switch actively examines the traffic and actively routes it to the appropriate receiving port. Routers do other things, too, including provide Network Address Translation, which allows you to fairly transparently share the single IP address your service provider gives you, and hides your LAN from most snooping eyes. They also usually have a DHCP server to automatically assign addresses to the devices on the LAN.

On any given LAN, having more than one DHCP server active can be a headache. You either have to carefully configure both of them not to interfere with each other, or you run into annoying (and sometimes difficult to trace) problems. Further, why would you want to have more than one server active? Most SOHO-level routers provide addresses for up to 253 devices, so it shouldn't be because of running out of addresses. And if you have your AirPport Base Station configured as a bridge, the router will assign addresses through it, so everything gets its own address from the same pool and everybody's happy.

[Pierre74]

Hi GHPorter!

Thanks a lot for your explanations.

I currently use the set-up you describe and indeed everything works fine.

I don't really _want_ the AirPort BaseStation to be second DHCP server. I just saw that I had the option to and was wondering which set-up is better.

I was wondering if there were advantages (e.g. performance, security)of not having the BaseStation bridge between AirPort and Ethernet. I figure if I turn off bridging and set the BaseStation as DHCP server for the AirPort network I will get two distinct LANs, each with it's own DHCP server: Ethernet and AirPort.

Pierre.

[ghporter]

Pierre,

You can indeed set things up the way you suggest, but I think you'll have more headaches if you do. Configuring the two different servers isn't a big deal, you just select an address range that you want each to work in and tell them each how many clients to deal with. However, keeping straight which computer is supposed to be part of which LAN can be a challenge. Also, unless you're really careful, you'll have problems getting the wireless computers to share files with the wired computers, and vice versa.

There aren't really any security advantages in having the two networks separate, either, since you're behind a NAT firewall. The bad guys can't really see anything but your router, and if you've taken the simple step of changing the admin user name and password to secure it, you're pretty well protected from anything coming in uninvited.