How do Static Route DHCP Assign IP Address to Vlan Client in the MX and MS Layer 3 Topology

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Marlon
Here to help

How do Static Route DHCP Assign IP Address to Vlan Client in the MX and MS Layer 3 Topology

Hi All,

 

I am new to my company's Meraki Network and I want to figure it out how it works.

My company Network is using this Topology in the article below

 

https://documentation.meraki.com/Architectures_and_Best_Practices/Recommended_Topologies/MX_and_MS_B...

 

The Layer 3 Switch is using HP 3800 and all the Vlans created on it. All the Static Routes are created on MX Appliance and each Route is setup with a DHCP Server to provide DHCP services to the clients. 

You can see between MX and Layer 3 Switch it is using an Access link, on Meraki Port is Access Port only Allow Native Vlan in this case is Vlan 50. 

1. What I don't understand how DHCP Server give IP to downstream clients when MX is using Access Mode to connect Layer 3 Switch not using Truck Mode? should the Link to Trunk?

2. For example, a new client A in Vlan 1 want to get a IP from DHCP Servers of Static Route 1, Layer 3 Switch will forward the DHCP request to MX, but how MX decide which DHCP server to assign IP to Vlan 1? 

3. I tried to create a new Vlan 3 on Layer 3 MX Switch with all the exact same setting as other Vlans, but somehow the client on the new Vlan 3 couldn't get an IP address from DHCP server, I am wondering where it is wrong. 

 

Any suggestions or any useful articles please share with me, Thanks first.  

 

Marlon_0-1693954093758.png

 

Marlon_1-1693956078063.png

 

1 Accepted Solution
alemabrahao
Kind of a big deal
Kind of a big deal

You should have to configure the DHCP Relay in you L3 switch.

 

Read the documentation about DHCP Relay.

 

https://documentation.meraki.com/MX/DHCP/Configuring_DHCP_Relay

I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.

Please, if this post was useful, leave your kudos and mark it as solved.

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10 Replies 10
alemabrahao
Kind of a big deal
Kind of a big deal

You should have to configure the DHCP Relay in you L3 switch.

 

Read the documentation about DHCP Relay.

 

https://documentation.meraki.com/MX/DHCP/Configuring_DHCP_Relay

I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.

Please, if this post was useful, leave your kudos and mark it as solved.

Hi @alemabrahao , thanks for the reply, I understand the DHCP Relay needs to be configured in L3 Switch, but I have gone through every menu on the HP L3 Switch Web page but couldn't find any place for DHCP Relay, unless there is management Portal I am not ware of that can configure Relay on this HP L3 Switch.  

 

Marlon_0-1693972649827.png


Also could the default Route configured on L3 Switch be acting as DHCP Relay (IP Helper)? 

 

Marlon_1-1693973015081.png

 

alemabrahao
Kind of a big deal
Kind of a big deal

As far as I know the IP helper is configured under the interface VLAN or in some cases on VLAN.

 

https://techhub.hpe.com/eginfolib/networking/docs/switches/K-KA-KB/15-18/5998-8164_mrg/content/ch12s...

I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.

Please, if this post was useful, leave your kudos and mark it as solved.
dimatt
Getting noticed

Hello,

 

Why you don't configure the DHCP server on the Layer 3 switch?

It's the best way.

I have the same topology, and i have configured the DHCP server on my MS switch.

 

Regards

 

Hi Dimatt, thanks for you reply. The L3 Switch is not Meraki Swtich, it's HP 3800-24G-2SFP and I couldn't find a setting to setup DHCP. 

 

Also in this Meraki Example, the DHCP server is setup on the MX, not on the Layer 3 Switch. 

https://documentation.meraki.com/MS/Layer_3_Switching/Layer_3_Switch_Example

 

Marlon_0-1694039992974.png

 

 

I am thinking replacing the HP L3 Switch with Meraki L3 Switch for future, but at current stage I need to figure it out how the HP Switch does the DHCP Relay as I couldn't find any setting for DHCP Relay. 

 

 

alemabrahao
Kind of a big deal
Kind of a big deal

Take a look at this video.

 

https://youtu.be/mml4J4fGrlk?si=mKoF570U9yYbvBTo

I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.

Please, if this post was useful, leave your kudos and mark it as solved.

Hi @alemabrahao , thanks for the Video, the HP 3800-24G-2SFP doesn't have the DHCP Relay menu, I am starting looking for other solutions. 

There is a Meraki Switch MS225 on the network and I searched this MS225 can do the DHCP Relay so I am planning to setup DHCP Relay on this MS225, but this MS225 is connecting to HP L3 Core Switch first, MS225 is not connecting to MX directly. 

My question:

If I setup a new Vlan on MS225 and setup a DHCP Relay to point to MX Gateway, although MS225 is not directly connected to MX, will the DHCP Relay work?  

 

Marlon_0-1694047026260.png

 

alemabrahao
Kind of a big deal
Kind of a big deal

It supposed to work.

I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.

Please, if this post was useful, leave your kudos and mark it as solved.

Hi @alemabrahao , Thanks for your work. 

I figured it out where to setup DHCP Relay on the HP Switch. 

This Switch is very weird, on the Web port it didn't give you option to setup DHCP Relay, but today I login via Telnet session and do show ip helper-address, I can see existing IP helper address for existing Vlan, and new Vlan I setup didn't have ip Helper-address. 

After I setup a new ip Helper-address for new Vlan, all working now, it makes all sense now. 

Thanks again for your help, this help a lot on identifying the issue. 

 

alemabrahao
Kind of a big deal
Kind of a big deal

Great, it's why I prefer to use the good old  CLI 😄

I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.

Please, if this post was useful, leave your kudos and mark it as solved.
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