Cisco Meraki C9300X-24HX ( DHCP ISSUE)

[nitin1234]

Hi all,

We recently deployed a Meraki C9300X-24HX running IOS XE 17.15.4.

We have a very basic setup:

• Created 5 VLANs on the core switch and enabled DHCP on the core for 3 vlans.
• Connected MR36 and MR44 access points to the same core switch and created two SSIDs.

We are seeing an issue where some clients are not receiving an IP address from the core switch. Based on packet captures, the DHCP server is responding with a DHCP NAK to the client.

At the same time, some clients are able to obtain IP addresses correctly.

Has anyone faced a similar issue?

[alemabrahao]

Is the AP port in trunk mode?

Have you checked for any DHCP conflicts?

If I understand correctly, the 9300 is playing the role of the correct core?

Can you share the SVI and DHCP configurations?

[nitin1234]

Is the AP port in trunk mode?

> yes, 

Have you checked for any DHCP conflicts?

> No conflict in dhcp

If I understand correctly, the 9300 is playing the role of the correct core?

>yes

Can you share the SVI and DHCP configurations?

> its vlan xx and we have enabled ( run dhcp server ) and reserved few IPs from 1 to 30. 

   and using google dns

[alemabrahao]

From what I saw, this version is still a candidate for stable, and there are some considerations.

Before you upgrade or migrate: key considerations

• After migrating CLI/DNA managed switches to cloud configuration source, please note that console and SSH access are no longer available. All management access is only available via the cloud Dashboard or the local status page through the rear management port.
• Please refer to the documentation (https://documentation.meraki.com/MS/Cloud-Native_IOS_XE/Cloud-Native_IOS_XE_Overview#Changes_in_Beha...) to familiarize yourself with management interface architecture changes.
• Layer 3 switches cannot run DHCP servers on uplink interfaces with IOS XE 17.15+. Post-upgrade, Interfaces with both Preferred Uplink and DHCP server configurations will have the DHCP server configuration disabled on that interface.
• Switches using the Alternative Management Interface (AMI) will require an L3 SVI to be configured for the same VLAN assigned to AMI. For AMI to work, your network must have AMI configured and your switch must have an SVI configured matching that AMI VLAN.
• After upgrading from CS to Cloud Management with IOS XE firmware, port mirroring configurations on module ports will not be retained. Users will need to reconfigure port mirroring on module ports following the upgrade.
• The 30-day grace period applies to licensing for Catalyst switches onboarded to Meraki Dashboard, allowing customers to trial cloud mode prior to fully committing. Valid DNA licenses can be converted to Meraki licenses through a qualified promotion process. Refer http://cs.co/9005aw6VH for more details.

If I were you, I would downgrade to the stable version (CS 17.2.2) and wait until iOS XE 17.15.4 becomes stable or wait for a new version.

I also suggest you open a support case.

[PhilipDAth]

You need to concentrate on why the DHCP server is responding with a DHCP NAK.

Have you got sufficient spare capacity in the DHCP pool?

If you look at he DHCP request, is the client asking for a specific IP address which is already in use?

[nitin1234]

Hi Philip,

Yes, we have a sufficient number of IPs. This is a new setup, and we have more than 200 IPs in a /24 subnet.

Currently, we have only 10 devices connected. The client is requesting a specific IP, which was assigned by the core to my device just a minute ago. I don't see any IP conflict. I've also created a new VLAN, a new subnet pool, and a new Wi-Fi SSID, but the issue persists with this new hardware — a C9300X-24HX running IOS XE 17.15.4.

We're experiencing some very unusual behaviour with this new Catalyst series.

At one customer site, when we change VLAN IPs or add a new VLAN, the dashboard reflects the changes, but we don’t see any updates in the routing table.