DHCP, IT guy confused me....

[Hansoon]

DHCP, IT guy confused me....

Customer had a problem with multiple IP-addresses in their network.
Installed 6 months ago a MFP. As usual do I hookup the machine and let DHCP issue an IP-Address. Than I change this address into a fixed address.
Until now life was good that way.

Today however it came to conflicts in their network. I discovered that somebody added an IP-Camera with the same address as my MFP. Talked to the IT-guy and asked him to change that camera. He said NO, you have to change your MFP cause you cannot use an address being within the DHCP range, it should be a fixed address outside of that, because the DHCP server will notice that the lease period is expired and cause problems. WTF?

Is that IT-guy right and am I doing it the wrong way since about 10 years? Had never any problems with it before.

Hans

[RRodgers]

Normally, you do not want to put a copier (or any mfp) in the DHCP scope unless you can lock in the IP for that device. Doing that would require a DHCP host that you can configure. I (we at work) usually start with .200 and work our way up from there.

I think it's always best to find something that is way up out of the DHCP range, that way you won't ever have to worry about conflics.

[Hemlock]

Best way to wash your hands of it is have the IT guy/gal give you a static ip addy to plug in when you do the install. This way, if there are any conflicts down the road, it's on them. Bonus: if they change the machine ip in the future the port will need to be updated in the driver(s). You get to put this back on them.

[jonhiker]

Best way to wash your hands of it is have the IT guy/gal give you a static ip addy to plug in when you do the install. This way, if there are any conflicts down the road, it's on them.

THis is the best way if it is a new install. I will sometimes put it on DHCP to grab the addressing scheme and then ping something above 200 to make sure it is available.

[Jules Winfield]

Most of the time when using DHCP you can reserve an IP address in the DHCP range by MAC address. The IT guy should know how to do this. You give him the MAC address of the printer, he creates an IP reservation based on the MAC address you gave him. Then all you have to do is enable DHCP. The printer will receive the IP address that was reserved for it's MAC address.

[Tonerbomb]

Most of the time when using DHCP you can reserve an IP address in the DHCP range by MAC address. The IT guy should know how to do this. You give him the MAC address of the printer, he creates an IP reservation based on the MAC address you gave him. Then all you have to do is enable DHCP. The printer will receive the IP address that was reserved for it's MAC address.

JW nailed it I've been doing it this way for years. It's always good.... unless you have to explain how to do this to the IT guy!!!!!LOL...

[blackcat4866]

My method is a composite of what you've already heard.

If there is IT (and several of my small customers answer "What IT?"), I'll start with the machine on DHCP, and ask the IT for an address. Often DHCP will pick up DNS1, DNS2, WINS, & domain, in addition to an open address. I like letting DHCP do the work for me.

Then I'll enter the desired address, or choose one in the .200+ range. You can ping, or use a utility like angryIP or NetScan to see what addresses are already assigned. The benefit to using the utility, is that even if the PC is off the network, AngryIP or NetScan will still see the address being assigned to a PC. Ping will just fail. It's not quite as sure fire. Make sure that you select Static. Most of the machines I work on will not scan-to-SMB to a DHCP address.

I'm pretty sure that you're in northern Europe, Hans. I don't know if our networks in the US are set up similarly. Does anyone know?

[Hansoon]

I'm pretty sure that you're in northern Europe, Hans. I don't know if our networks in the US are set up similarly. Does anyone know?

Based on the threads I see I would say yes, Cat.

Hans

[Andy21]

US and Europa have the same set up for networks. The static IP address is the best solution.

[Hemlock]

The problem with letting DHCP grab you one and then making it permanent - when the CEO comes in with a laptop it's most likely gonna have a static ip that just happens to match the one in your device. When he gets done chewing on the IT staff for his connection errors, they're gonna point the finger at you. At which point you get a service call to go out and smooth ruffled feathers.

So yeah, let the IT guys assign it.

[Hansoon]

One of our colleagues on another forum had a very interesting reply:

"The IT guy is actually right for once. While you may have been getting away with your method all this time, Hans, a lot of newer routers will cry foul if you do that.

Say your network is operating in the range 192.168.1.XXX, and say the router has a DHCP pool ot 100 addresses, from 192.168.1.100 ~ 192.168.1.199. If you let your copier snag an address via DHCP, say that it takes 192.168.1.105, and then you change that to a static address and reboot, while at this time nothing may be using the .105 address, because you manually set that address and it was not assigned via DHCP (by the router), the router still thinks that address is free and will assign it to the next device that comes knocking. You may get away with your method for a time, especially if they have their DHCP lease period set to a very long time (I've seen as long as two weeks), but once that lease expires, the router will no longer be "holding" the .105 address, and will assign it to any device that comes calling.

There are two ways to handle this.

The first, and the preferred method, is to go ahead and do the first part of your setup like normal, connect the copier and let it grab an address via DHCP. The next step, instead of changing that to a static address, is to go into the DHCP server (whether it be the router itself, or another computer acting as the DHCP server) and create what is called a client reservation or MAC reservation. Each NIC has a distinct MAC address which acts as a sort of serial number, totally unique to that card. Creating the reservation tells the router "Okay, the copier at 00:FF:C3A:83:22 (or whatever) should always get 192.168.0.5" Even if the copier is off or disconnected, and so nothing is currently "on" the .105 address, if another device comes on the network and requests a DHCP lease, the router will go "Okay, the next available address is .105... but hey, that is reserved for a certain device. Since you are not that device, you get .106 instead." In a situation where the client is already using DHCP, the reason that this is the preferred method is that all your addresses still fall within the DHCP pool, and since the router is still handling all the addressing (with a reservation for your copier), the potential for conflicts is reduced to nearly zero. IT admin can simply look at the router at a glance and see not only all the devices connected and using a leased (the term for a DHCP-assigned) address, but also which addresses are reserved. At a glance, he knows all the active IPs in-use on his network.

The second method is to do as the IT guy remarked, and create a static IP outside the range of the normal DHCP pool. Now, if their DHCP leases all start at .100 or .200, it's pretty to tell that scheme and just shoot low. But if the leases are all .3, .4, .7, etc... where does it end? 50? 100? It's hard to say, and even more, some routers are so possessive of their DHCP pool that if you manually assign an address within that pool, it goes "Hey, who's that stealing one of my addresses? I'm gonna shut you down, buddy." And you'll lose WAN or even LAN connectivity until you change it. You can go into the DHCP server (again, this may be the router itself, or another computer acting as the DHCP server) and check to see what the DHCP range is, but if you're going that far, why not take 10 seconds to do it right, and just create a reservation? The danger here is exactly what you just discovered: If you don't know for sure where the DHCP pool ends, you could very well end up with just this kind of conflict. Admittedly, it's much less of an issue in a small office with 3 computers where it's highly unlikely that you'll ever come close to exhausting the pool. But in larger offices with many more machines, the need to do it right is much greater.

Last edited by BayshoreOffice on Tue Feb 15, 2011 5:47 pm; edited 1 time in total"

Hans

[tinnyjay]

DHCP, IT guy confused me....

Customer had a problem with multiple IP-addresses in their network.
Installed 6 months ago a MFP. As usual do I hookup the machine and let DHCP issue an IP-Address. Than I change this address into a fixed address.
Until now life was good that way.

Today however it came to conflicts in their network. I discovered that somebody added an IP-Camera with the same address as my MFP. Talked to the IT-guy and asked him to change that camera. He said NO, you have to change your MFP cause you cannot use an address being within the DHCP range, it should be a fixed address outside of that, because the DHCP server will notice that the lease period is expired and cause problems. WTF?

Is that IT-guy right and am I doing it the wrong way since about 10 years? Had never any problems with it before.

Hans

Their system is configuret like that.
But,i think its not your problem.