Question about DHCP and network performance

tomdkat

tomdkat

Registered
So, I support a couple of iMacs (PowerPC based, I believe) that run OS X Tiger.

When DHCP is configured, each iMac is assigned an IP address and network access works just fine. There is a particular application they use that works but is a bit sluggish to start.

When DHCP is NOT configured and I assign the IP address, netmask, default gateway, and DNS server manually, this particular application they use starts up much more quickly and seems to run faster.

My question: why would DHCP have any impact on how any given application runs? I mean by the time the application starts, the machine should *already* have its IP address assigned, it's netmask and default gateway setup, and DNS server(s) configured.

Thanks!

Peace...
 
What is the application? What portion(s) of the application depend on the network?

Without knowing more about the program, it's tough to say what exactly is going on.
 
It's a dental application called "MacPractice". It uses a MySQL database to store the patient information and it uses IP to connect to a database server running on a remote machine. (I'm not sure if TCP or UDP is used as the transport protocol so I left that out).

The strange thing is, we're using a raw IP address for the address of the database server so there should be no DNS lookups, etc., going on to resolve the IP address of the remote server.

When DHCP is configured, it takes an unusually long time for the connection to the remote server to be established.

When DHCP is NOT configured, it takes far less time for the connection to the remote server to be established.

The MacPractice configuration has NOT been changed at the raw IP address of the remote database server is used regardless of DHCP being enabled or disabled. It's just strange that it runs faster if DHCP is not enabled, which makes me think there might be something weird going on at the DHCP level in OS X.

Peace...
 
Could there possibly be an IP conflict, in the sense that the static IP of the mySQL server is somehow being handed out to another machine via DHCP?
 
ElDiabloConCaca said:
Could there possibly be an IP conflict, in the sense that the static IP of the mySQL server is somehow being handed out to another machine via DHCP?
Click to expand...
I don't think so because I'm not being alerted to any conflicts. The database server has a static IP address and there are only a handful of machines on the network.

The database server has IP address 192.168.1.100 and the iMac that had a DHCP configuration had an IP of 192.168.1.2 or .3. There are three machines on the network that used to have DHCP configurations and two that had static IP addresses assigned in addition to the server having the static IP as displayed above.

The other thing to make note of is this application appears to be running "faster" since changing over to a static IP address.

I'm not asking you guys to troubleshoot what this particular app is doing but I was looking to find out if there's any quirky with DHCP support on Mac OS X.

EDIT: Over the weekend, I'll see if I can conduct a test where I ping the server IP address (192.168.1.100) with one of the iMacs configured with a static IP and with DHCP and see if there are any differences in response time. The netmask on all the machines is 255.255.255.0.

Peace...
 
tomdkat said:
I'm not asking you guys to troubleshoot what this particular app is doing but I was looking to find out if there's any quirky with DHCP support on Mac OS X.
Click to expand...
Not that I know of -- I run several Mac network setups, about half with static, half with DHCP (with some scattered statics for printers and servers, etc.), and both operate smoothly and correctly.

I don't know of any quirks or wonkiness or "catch-22s" with the DHCP implementation on OS X.
 
Thanks! :)

EDIT: Well, this turns out to be an application specific issue. Apparently, the server records IP address information for each user id that logs in. If the assigned IP address changes, it takes longer for the server to react to that IP address change which causes the initial connection to be slower than normal. *Sigh*

The more I learn about this application, the less I like its underpinnings.

Peace...
 
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