Recommended Switch setup with PXE Boot

[a_naipaul]

Hi Guys,

I have a quick question regarding deploying PXE boot into a LAN environment, if you could please advise on whether the below is a recommended solution that would be great:

• Place the PXE Server on a separate subnet to your user machines
• Configure a Layer 3 Vlan which utilises IP helper address function to pass the PXE requests to the PXE server

Also, I have the following questions:

• If the recommended solution is to place the PXE server into a separate subnet would you recommend only using specific ports for PXEBOOT? As I would assume this port would then need to become a trunk port? As opposed to an access port.

Any help would be greatly appreciated.

[balaji.bandi]

You understand is correct, in the setup

PXE boot server can be any VLAN as long as it is reachable.

[a_naipaul]

Hi there

Thank you for your quick response!

Ok great - so I could leave the server in the current user vlan as we do not want to be limited to what ports will be used for pxe boot and we can leave them as access ports.

If we already are using 2 x IP helpers for DHCP (primary and backup) would there be an issue adding a 3rd just purely for PXE?

Thanks!

[Richard Burts]

I think there are multiple parts to the answers to your question.

- multiple helper addresses. there is no issue in adding a third helper address. I think there are some platforms that limit the number of helper addresses, but I think that kicks in around 16. 3 helper addresses should not be an issue.

- why are you asking about additional helper addresses. I understand your comment to be that you will leave the server in the same subnet/same vlan as the clients. Where is the need for a helper address?

- I do not understand your comment about trunk ports. Putting the server into a separate vlan/separate subnet does not have any thing to do with needing a trunk port. It only would require inter vlan routing.

HTH

Rick

[balaji.bandi]

I have seen a scenario, some orgaisation need 2 different IP helper for only DHCP leave 3 one for PXE boot, but your case different.

[a_naipaul]

Hi Richard,

Thank you for your response,

Apologies, I think I am completely over complicating this - I was advised that putting the PXE server in a separate vlan was best practice and I am not sure why – Are you able to confirm?

I think I will look to just add the extra helper address to the existing data vlan and make sure the server is reachable on the same data vlan or a new one.

Thank you for your help!

Hi Balaji,

I think this is exactly what we will look to do have 2 helpers for DHCP and another one for pxe – Thanks for this.

[Richard Burts]

We do not know much about your environment. I am assuming that your network is fairly small and probably has all users in a single vlan/single subnet. Is my understanding correct? If so then I would not agree that it is best practice to put PXE server in a separate vlan. If you originally had a single vlan then I believe that best practice is to put PXE server in that vlan. Clients will send requests as broadcast, the server will receive the request and respond. All will work with no need of helper addresses. 

If a network has several vlans/several subnets then I could perhaps see some benefit to having the PXE in a separate vlan. If a network started as a single vlan then creating a new vlan for PXE is just adding complexity and I do not see any benefit in it.

HTH

Rick

[balaji.bandi]

that should be ok.....but we have seen some older setup more than 4 -  PXE not able to pickup due to timeouts.