• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

How to give DHCP lease to multiple subnets on multiple vlans

G

gmc8757

Member
I have a question about DHCP. I'm trying to come up with a new addressing scheme with multibple vlans, then multiple subnets within each vlan. For example: I'll have one for my infrastructure management devices, and within there i'll have 3 subnets(one subnet is for one part of the campus, the second is for the other side of campus, and the third is for remote sites which are on our network connected by point to point fiber). The same thing goes for say a Data vlan where it will have the three unique subnets as well. The IP Voice will have it's own vlan with three unique subnets and so on with Wireless Data, Wireless Voice etc. My question is, do you see any downside to this? having this many vlans with different subnets in each? The amount of subnets will build up very quickly considering each subnet in each vlan will be it's own unique subnet. Also, how will the dhcp server know that a Data device was plugged in and is supposed to be on a certain vlan within a certain subnet and give it the appropriate ip opposed to a infrasuctrure management device being plugged into the same switch but supposed to be on a different vlan with a different subnet and give it a totally different ip? Does that make sense at all? I really appreciate any help you can give. Thanks.
 
I would think that with the DHCP and the voice that you could assign a range/ reserve a range in the DHCP server for the voice system and make sure they only draw from that range.

The only "downside" I can think of to this is complexity and its reliance on so many other parts. You have to ask yourself how much is going to go down if one of the parts goes down. Is it a house of cards that will come down if one of the VLANs (voice?) goes down?

Also with all the VLANs you need to make sure your router(s) can handle all that traffic. But if you're running fiber between areas my guess is that you probably have the funding to GET (if you don't already HAVE) nice routers.

Personally I think it sounds like a pretty cool setup, just complicated, which can lead to troubles when trouble shooting. You might want to try and deploy something like this between a couple of virtual machines nd then take different parts down and see what is effected when certain parts fail.
 
Thanks a lot for your comments. We're actually doing a huge network upgrade of all the equipment, hence the new addressing. The routers being able to handle them won't be an issue i don't think.

I don't know really waht you mean when you say for example we lose one of our voice vlans. How would we lose only one vlan and not the others that reside on that same cabling?
 
I was using it as an example. I guess what I meant was if a subnet was to go down how would that effect everything else. And it's questions like that, "Why would we loose only one vlan?" that need to be asked. Who knows WHY it might happen, the question is what WILL happen. (IE: Port failure on a switch or something...)

Essentially the point was complexity and dependencies.
 
I just didn't know it was even possible to lose a vlan all together..but you're right..anything can happen.

It is very complex, i'm just worried it's too complex?
 
I'm sure there is a point where it would be TOO complicated, but honestly it seems to make sense to me. (It keeps things nice and separated) I think you just need to test it a bit and make sure it's not too complex. Setup a test maybe with a computer computers and a couple virtual computers running on them and then randomly turn things off and see what happens.

There is nothing wrong with complex as well as you know what is going on and can explain it to someone else. (Besides that is bragging rights around the IT table some-day. "I had this network once...") I guess the point here is to make sure you can handle the "beast". =)
 
Ok, would it change anythying if i told you i have only about 1000 hosts, and about 1500 voip phones?

that's a ton of subnets/room for growth.
 
I like the idea of vlans because I can plug into the switch and be on any vlan I want no matter the location.

Also, not sure if this is 100% correct, but doesn't having vlans help with packet prioritization or qos?
 
Originally posted by: gmc8757
I like the idea of vlans because I can plug into the switch and be on any vlan I want no matter the location.

Also, not sure if this is 100% correct, but does having vlans help with packet prioritization or qos?
Click to expand...

I'm not 100% on this as well, but I was pretty sure you had to have VLANs to pull off QoS as well.
 
Say you have an IP phone. in the back, they ahve the jack for a pc to be plugged in, where the phone kinda acts like a hub so you only have one line going back to the switch. How would the phone get one IP and the PC get a different one? It's just one port on the switch. I don't understand that part, can anyone help? Thanks.
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top