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DHCP services for static routes

Hello everyone,

I am aware of the option to use DHCP services on the MX for the configured static routes, but it doesn't seem to work. Before raising a support ticket for creating a bug, just want to know if anyone used this feature and got it to work?

None of the online forums show anyone using this feature, so just curious.

Thanks,

Jaswanth

22 Replies 22

Can you provide some screenshots of your config? You have a static route on the MX to a destination network and you have a VLAN on the MX configured for DHCP relay to a server in the destination network of that static?

Ryan

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please see my reply below

I don't understand your question. Could you explain it a different way?

The above screenshot is how my config looks like on the MX.

So the topology looks like below:

Client (Should be in the VLAN:20 (192.168.64.0/24) >> L2 switch >> L3 switch (has an SVI for VLAN 20 with 192.168.64.1) >> MX LAN port.
I don't have a separate DHCP server in my network and my L3 switch cannot act as a Server, so I want to use the feature on the MX that can act as a DHCP server for the static routes.
The documentation explains that we can do it: https://documentation.meraki.com/MX/DHCP/DHCP_Services

I think I understand. You want the MX to be the DHCP server but give out a default gateway of your L3 switch.

Alas you can not do this on an MX. It will only give out itself as the default route.

Hi Phillip,

I added, the link to the Meraki documentation and the screenshot of the specific part that tells that it should work.

Have you tried adding a custom option 3 setting the gateway to the IP in the subnet that is the switch?

i.e. MX is on 192.168.0.2/24

DHCP gives out 192.168.0.3-254

Switch is on 192.168.0.1

Set option 3 to 192.168.0.1 and clients will use that as a gateway.

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Option 33—Static route option. It specifies a list of classful static routes (the destination network addresses in these static routes are classful) that a client should add into its routing table. If both Option 33 and Option 121 exist, Option 33 is ignored.

I have never tried it before but maybe you can perform a configuration like this:

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

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This article explain how you can do it on Palo Alto, so maybe you can use the same format.

https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClEICA0#:~:text=DHCP%20Opt....

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

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I don't want to add any static routes into the client. All I need is MX to act as a DHCP server for my clients that are behind a L3 switch.
with the config that I already had, the MX receives the DHCP relayed unicast, but doesn't reply with an offer even though we had the config.

You need to set Ip helper address on SVI configured on your L3 switch.

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.

As I said in my above replies, I already set the IP helper address on the SVI in the L3 switch.
here is the troubleshooting that I have done so far.
Took a pcap on the MX LAN, MX sees the DHCP discover coming in as a unicast to the MX IP for the transit VLAN, but it just doesn't reply back with an offer.

You didn't say that, but ok. I'm setting it up on my client and it's been working fine.

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.

Basically, you can create a transit VLAN between L3 SW and MX, then you can create a static route to the destination VLAN and configure DHCP for this static route, and finally configure the IP Helper Address on the SVI with the MX IP .

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.

Are you able to see MX replying back with the DHCP offers?
I have all the configuration done, but I don't see the MX sending the DHCP offers downstream.

Yep, The Core is a HP Switch and the MX is acting as a DHCP server and default route for the Switch core.

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.

maybe its a 17.x bug.. are you running 16.x @alemabrahao and @JessyJ 17x?

@ww yes, I'm running version 16.16.8.

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.

Interesting idea @alemabrahao . If Windows support option 33 then that should work.

Did you ever find a solution?

@Jesse , did you find out the solution in the end? I am having the exact the same issue and got stuck now.

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