2 Routers with DHCP Put On same unmanaged switch

[Iloveyou]

Let's suppose I want dhcp redundancy.

I have 2 ISP cisco router.

R1 is configured as 192.168.1.1/24 with dhcp enabled.

R2 is configured as 192.168.2.1/24 with dhcp enabled.

It is both connected to the same unmanaged layer 2 switch.

What happens to the end devices connected to the switch?

Is there any other way to achieve dhcp redundancy?  

[balaji.bandi]

Depends on which router reply quick that DHCP address get for the user.

i would suggest to have out of the box, small Rasberry Pi for DHCP Server in the network.

But again the question come here ? how are you going to use both the ISP network ? ( you need to intellegent device between switch and routers to make that decision.

[Iloveyou]

So it will work?

There wouldnt be any dhcp conflict on the unmanaged switch?

R1 and R2 have their own static route to isp so it wouldnt be an issue.

I am afraid because there are some servers that need static ip

[balaji.bandi]

If you happy user get random IP address and Router can do NAT - is this acceptable ?

[Joseph W. Doherty]

"There wouldnt be any dhcp conflict on the unmanaged switch?"

That depends on what you're doing (which is why I made assumptions in my first reply)and what you consider is a "conflict".

"R1 and R2 have their own static route to isp so it wouldnt be an issue."

Again, depends on what you're doing.

"I am afraid because there are some servers that need static ip"

If some server are using a static IP how does DHCP become a consideration?

[Richard Burts]

The original post describes 2 routers and 2 networks which implies separation of traffic but they are connected to an unmanaged switch. But the unmanaged switch treats everything equally and there is no separation of traffic on an unmanaged switch. If you want the 2 networks to be separate you need a managed switch.

[Joseph W. Doherty]

"What happens to the end devices connected to the switch?"

You're also implying R1 and R2 .1 interface is connected to the unmanaged switch?

If so, each router only has that /24 networking, including for a DHCP pool?

If so, you have a "race" condition (much like multiple DHCP servers supporting the same network block).  Also what @balaji.bandi is describing with his first reply's first sentence "Depends on which router reply quick that DHCP address get for the user."

I.e. both will obtain the DHCP request and both will make a offer, fastest wins.

"Is there any other way to achieve dhcp redundancy?"

Yes.