Layer-2 only network and Layer 2 Handoff Border

Erich Schommarz · ‎03-03-2022

We have a SDA environment where we created a L2 Vlan with a Gateway (GW) outside Fabric. For the GW we created a L2 Handoff on the border, for the network we created a L2 Network with the option "Layer-2 only". Now we are facing some issues with ARP not working in one direction (Outside to Fabric) and also a few devices which have issues with DHCP. In addition other L2 NW with same configuration work without issues until now over separate L2 Handoffs.

For the "Layer-2 only" option there is a message that "This is an early-release feature. This feature should not be enabled

without explicit guidance from a Cisco technical expert. We are running following DNA Center version: Version 2.2.3.4

Are there any known limitations for the function "Layer-2 only" especial with combination L2 Handoff?

@Scott Hodgdon , you presented once a presentation at the PVT with new features "Gateway on Firewall Outside Fabric". There you mentioned that a Dummy SVI is required and L2 flooding. With the "Layer-2 only" dummy SVI is not configured. If you see this maybe you have some tips recommendation for us which would be very much appreciated.

Thanks for any answer to this function / feature in SDA.

Jonathan Cuthbert · ‎06-22-2022

@Erich Schommarz wrote:

We have a SDA environment where we created a L2 Vlan with a Gateway (GW) outside Fabric. For the GW we created a L2

For the "Layer-2 only" option there is a message that "This is an early-release feature. This feature should not be enabled

without explicit guidance from a Cisco technical expert. We are running following DNA Center version: Version 2.2.3.4

Are there any known limitations for the function "Layer-2 only" especial with combination L2 Handoff?

I'm sorry to hear you are running into challenges. This feature is not yet in General Availability, and our ask is to do just as the UI instructs.

To troubleshoot or advise on this, we really need to sit down and discuss. As an early-release feature, explicit guidance from a Cisco technical expert is necessary, please.

If you are in the partner community, please reach out in the WxT Partner Space. If not, please reach out through your Cisco Sales and Support team.

Erich Schommarz · ‎10-17-2022

Hi Jonathan, just saw your answer now. Thanks for taking time and answering to it. At the end in our case it was a config failure in the underlay.

93meehanlj · ‎10-17-2022

I've done some investigation on an issue I'm currently having with a L2 fabric WLAN and my first set of brief Wireshark captures are showing the same symptoms. While I dive in a bit deeper to confirm, did you get to the bottom of the issue @Erich Schommarz ?

Erich Schommarz · ‎10-17-2022

Hello, so in our case it was an issue with the underlay. Multicast was not configured correctly between all switches. We only had "ip pim sparse-mode" between edge and border. Between the two border the command was missing. That solved in our case the issue.

But due to complexity there are several things which could cause the problem. Only thing I can advise you is to try to troubleshoot further with the documents which are available.

In addition to the following document

https://www.cisco.com/c/en/us/td/docs/cloud-systems-management/network-automation-and-management/dna-center/tech_notes/sda_fabric_troubleshooting/b_cisco_sda_fabric_troubleshooting_guide.html

maybe you find some good slides from Cisco Live or when you are a partner you find a session from TAC in salesconnect.cisco.com (EMEAR_EN_TAC_Sep_2022_Cisco_SD_Access_L2_Flooding) which maybe can help you.