Open Stack

Hello.

I have a question about the VXLAN support on OpenStack.

As far as I know, the OVS operates like the below:

1. A tag number is created to identify each tenant, and it is used between
br-int and br-tun. Furthermore the tag number is identified as a VLAN ID (I
checked it via tcpdump).

2. After the packet arrived at br-tun, it is encapsulated and VNI (VXLAN
Network Identifier) is attached. The binding information between the VLAN
ID (tag number) and the VNI is stored in OVSDB.

If the operation is correct, it seems that the number of tenants which can
be created is still limited to about 4000, which is the supported range of
VLAN, because the tag number is used to identify each tenant at the inside
of br-int regardless of the supported range of VNI.

If more than 5000 tenants are created in a Compute Node, how could be these
identified after the packet arrived at br-int? In the theory, the 4500th
tenant should have 4500 tag number but the tag number is presented as VLAN
ID so that it cannot be assigned over 4096.

Any advice and comment would really be appreciated.

Best regards

Byeong-Gi KIM
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