Meraki Full-Stack Design Related Question - Dropping Untagged traffic

ToryDav
Building a reputation

Meraki Full-Stack Design Related Question - Dropping Untagged traffic

What concerns would you have when removing VLAN 1 entirely from a Meraki MS/MX/MR network and dropping untagged traffic across all interconnections (trunks)?

I know there are some requirements to keep VLAN 1 as native VLAN in a mixed Meraki/Catalyst/Nexus environment, so this question focuses on Meraki hardware only for discussion sake.

To meet network security best practices I often wonder, why not remove VLAN 1 from the MX, tag all the subnets across the MX LAN ports to MS switching and configure all the trunks to drop untagged traffic. 

I don't see any issue but have heard sometime dropping untagged traffic could cause problems, I just haven't seen these problems myself.
 

Thoughts? Opinions? 

7 REPLIES 7
alemabrahao
Kind of a big deal

Where did you hear that statement? I needed to drop in some specific cases and never had any issues.

ToryDav
Building a reputation

Which statement? Assuming the statement about keeping VLAN 1 - The link RaphaelL shared is it. 

I have seen issues in the field with this though - a lot of issues in mixed vendor environments due to STP where there are rapid STP Per Vlan instances of spanning tree running. 

alemabrahao
Kind of a big deal

""I don't see any issue but have heard sometime dropping untagged traffic could cause problems""

 

alemabrahao_0-1669763421502.png

despite what the documentation says I can't see this as a problem, but ok.

 

cmr
Kind of a big deal
Kind of a big deal

If you set a VLAN as native and don't include it in the trunk and do the same on a Cisco Catalyst switch at the other end, then the link will not pass the traffic in the native VLAN, I can confirm this from experience... 

ww
Kind of a big deal
Kind of a big deal

the stp  is using a native vlan. So as long you make sure you never have a loop (by the network admin/user error), and dont want/use redundancy based on stp blocking on your network,  it should work. 

PhilipDAth
Kind of a big deal

>What concerns would you have when removing VLAN 1 entirely from a Meraki MS/MX/MR network and dropping untagged traffic across all interconnections (trunks)?

 

This will prevent spanning tree packets from being forwarded and may result in an incorrect spanning tree being formed.

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