MR32 in Bridge Mode Connected to 4948 ARP issues

[marhill2]

Hi as the title states I have a Meraki MR32 connected to a Cisco 4948 L3 switch that issues my DHCP for clients connected to the Meraki AP in Bridge mode. The problem I am having is some devices will not connect unless I reset the 4948. After further investigation it looks like some devices are registering entries in the ARP table on the 4948 and some are not. This may not be an issue with the Meraki box but was hoping I could get some help or a possible explanation as to why this is happening.

Thanks!

Marcus

EDIT: Thought I would add, the clients that are missing show up in the DHCP binding table but not in the ARP table

[MilesMeraki]

Are you using any VLAN's in the design or is this a full flat network? Have you attempted taking any packet captures from the MR32 on the wired and wireless interfaces?

[marhill2]

I have not done any packet captures as it is random and I dont really know what I would be looking for. As far as the VLANs are concerned, yes I am using VLANs and have an SVI on my switch. I think have an access port connected to my Meraki device connecting it to the VLAN.

[MilesMeraki]

The packet captures would allow us to look at the ARP/DHCP traffic to try and isolate where the issue is lying and troubleshoot. If the issue is sporadic it could be hard to troubleshoot without a live example of the problem happening.

Have you ensured that the wired link between the AP and switch is in Trunk (802.1q) mode and is set to allow all the required VLAN's across? What's the native VLAN's being used on each port, do these match?

[marhill2]

Sorry for the late response I went out of town this week and it was fixed as of when I left. No sooner did I get to my destination did my Fiance call and say the internet was down again. When in reality it was just the WiFi.

To answer your question right now I have it in access mode and accessing the VLAN I want my wireless clients to be apart of. There shouldn't be any other VLAN traffic on the link. Should I try to put it in trunk and only allow the VLAN I am intending to use across it?

Thanks!

[PaulRusso]

I would recommend putting it in 802.1q trunk mode and allow your management VLAN and production VLAN over the trunk (I typically allow all VLANs across the trunk and only allow access using the VLAN tagging option on the SSID; this comes in really handy if you want to assign a group policy to a device to put them in a different VLAN when connected to the same SSID).

On your 4948 you can configure the port with switchport trunk native vlan (ManagementVLAN), and then make sure you do not tag the VLAN on the AP configuration page (Wireless > Access Points > Click on the AP > LAN IP (edit button)). You will also want to make sure that you use VLAN tagging (Wireless > Access Control)  to ensure that your users are going to be in the prod VLAN.

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