Hi Alex, Thank you for the reply!
Advertise-svi-ip is for advertising the primary IP on the local gateway/SVI for a VNI or all VNI's, depending on where you put the knob in the config. That indeed does advertise a MAC+IP of the gateway and makes it reachable on the EVPN network. Usually that's not needed (because of the anycast-gw), unless you want to test reachability or use a VNI for a management network to reach the host.
But lets say that you start a VM and it talks to some host on the internet, in that case it needs to contact it's local anycast gateway and the local SVI learns it's IP and MAC and adds it to the neighbor table in kernel and FRR creates a type-2 MAC+IP route, all is good, it gets it data and goes silent. After a little while the neighbor entry, in kernel, times out (garbage collected) and gets thrown away, the Type-2 MAC+IP gets thrown away with it... Now, traffic entering the subnet towards the VM will most likely go through another hypervisor, thus taking a suboptimal path.
I hope I'm laying down the issue properly. So I'm wondering how this issue was solved in Cloudstack.
Best regards, Julius Thor On 7.3.2025 18:53, Alex Dietrich wrote:
Hi Julius, When I deployed this, I did not have to do anything at the instance or VM startup to produce the MAC+IP routes. I may have had a line or two in the FRR configuration on the host to make sure it was advertising the Mac-IP automatically. It may have been ‘advertise-svi-ip’. The bigger challenge I had in integrating this with an existing EVPN VXLAN deployment was handling VNI mapping, which was not so fun 😊 I did end up with a “successful” deployment, so let me know if I can be of further assistance. Thanks, Alex From: Júlíus Þór Bess <jul...@1984.is> Date: Friday, March 7, 2025 at 1:33 PM To: users@cloudstack.apache.org <users@cloudstack.apache.org> Cc: w...@denhollander.io <w...@denhollander.io> Subject: EVPN-VXLAN to the host type-2 MAC+IP routes EXTERNAL Hi guys, I see that some of you are using or have been experimenting with EVPN-to-the-Host setup and I'd like to know how you are managing the neighbor table entries to produce the Type-2 MAC+IP advertisements. Are you using static entries added on VM startup (hook script, maybe?) or what? Julius Thor
