topic RE: DHCP Standard Practise in ExtremeSwitching (EXOS/Switch Engine)

DHCP Standard Practise

Ian_Broadway — Wed, 18 Jan 2017 19:27:00 GMT

I have a question regarding DHCP.

Whats the standard practise for implementing DHCP helpers.

Our current setup, we use UDP profile on all our vlans on our core switches that require dhcp services. this is an inherited design before my time.

would it be more beneficial to go down the bootprelay route?

are there any other options? pros and cons for each?

Many Thanks
Ian

RE: DHCP Standard Practise

OscarK — Wed, 18 Jan 2017 19:36:00 GMT

In early days UDP helper was the only method to be able to distinguish between vlans and DHCP servers.
Nowadays you can enable bootprelay per vlan so you can use bootprelay without enabling it for all vlans. Still I think if you need different DHCP servers for different vlans UDP profile is the only config possible.

RE: DHCP Standard Practise

Ian_Broadway — Wed, 18 Jan 2017 19:41:00 GMT

We use 2 DHCP servers for all our vlans, I assume you can specify more than one server within the bootprelay config?

RE: DHCP Standard Practise

Jarek — Wed, 18 Jan 2017 19:41:00 GMT

For example rel. notes 15.6 says that the maximum number of BOOTP or DHCP servers per virtual router is 4

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Jarek

RE: DHCP Standard Practise

Jarek — Wed, 18 Jan 2017 19:48:00 GMT

Ian, it depend what you need .

Oscar, I think you can use bootprelay with more DHCP servers, with additional config on server: agent.circuit-id, agent.remote-id, class, allow members of ... and so on.
It will respond only to configured "class members".

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Jarek

RE: DHCP Standard Practise

Ian_Broadway — Wed, 18 Jan 2017 19:52:00 GMT

Hi,

the scenario is, we have two DHCP servers and I would like all DHCP requests for 20 VLANs to go to these servers.

is it a case of;

configure bootprelay add "DHCP Server IP 1"
configure bootprelay add "DHCP Server IP 2"

configure bootprelay vlan "vlan 1"
configure bootprelay vlan "vlan 2"

and so on.

RE: DHCP Standard Practise

Jarek — Wed, 18 Jan 2017 20:05:00 GMT

Simpler:

1) confgure bootprelay servers

configure bootprelay add 1.1.1.1 vr VR-Default
configure bootprelay add 2.2.2.2 vr VR-Default

2) enable bootprelay

enable bootprelay - "Enables the BOOTP Relay function on all VLANs"

"If DHCP/BOOTP Relay is enabled on a per VLAN basis, make sure it is enabled on both theclient-side and server-side VLANs."

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Jarek

RE: DHCP Standard Practise

Ian_Broadway — Wed, 18 Jan 2017 20:11:00 GMT

I was going to say, not every vlan is DHCP serviced so would i stick with my example?

RE: DHCP Standard Practise

Jarek — Wed, 18 Jan 2017 20:12:00 GMT

disable bootprelay vlan XXX

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Jarek

RE: DHCP Standard Practise

Jason_Grubbs — Mon, 07 May 2018 20:50:00 GMT

I know this is an old post, but would this configuration still be the same when working with dhcp servers in a load balancing configuration (windows server 2016)? List both servers? Does it matter which one is first?