Posted on June 5, 2015 7:05 pm
 |  Asked by Lukas Hubschmid
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Hello everybody,

I have configured the following VXLAN networks using VMware vShield which should be mapped to VLANs on a virtual Arista Switch (vEOS 4.15.OF):
VNI5000 / Multicast / Map to VLAN 500
VNI5001 / Multicast / Map to VLAN 501
VNI5002 / Multicast / Map to VLAN 503

But on the interface vxlan 1, I can only set one multicast-group on the interface vxlan 1. Is there the possibility to set multiple multicast-group on this interface (one multicast-group per VNI)?
I also cannot create more than one VXLAN interface – is this a general limitation or only from the vEOS?

Many thanks in advance!


Posted by Alexis Dacquay
Answered on June 5, 2015 8:39 pm

Hi Lukas,

Only one Multicast group is supported today. There can be only one VTEP per switch, hence only one VTI (the VXLAN interface IP address). The workaround for the multicast side would be to select a single multicast group on the VMware side. Or to have a different EOS listening at a different multicast group. I suppose you only use vEOS for testing/lab. Just a reminder: vEOS is not suitable for forwarding dataplane traffic in a production environment (traffic is CPU switched).

You could also envisage a Unicast-based solution (with HER: Head-end-Replication), or integration with OVSDB. Both OVSDB and HER are used to distribute or resolve MAC/VTEP information, but only for unknown addresses. In multicast, HER or OVSDB, known addresses are always unicast.

The preferred approach by Arista and the market to address distribution/resolution in VXLAN is Unicast, you could see that deployments and new solutions all are (or becoming) Unicast.

Since you mentioned vShield, I could suggest you look at NSX.

For more details on the Arista VXLAN products and implementations, you could contact your local Systems Engineer, as it could be a long discussion, and depends on what you currently have availalbe in your lab, and what your try to achieve.





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