Open Stack

Dear George

Thank you for the reply.

I'm a little confused about your reply.

Can be the same tag number assigned to different tenant? For example, I
assume the situation where a subnet 1 assigned tag number 1 and it belongs
to tenant A, and a subnet b is also assigned tag number 1 and it belongs to
tenant B. Or, should be the tag number different even if subnets belong to
different tenant?

If the later case, the tag number seems much more strictly limited, because
a tenant can have many subnet. If a subnet has 10 subnets, which means 10
tag numbers must be assigned, the openstack only create about 400 tenants.

Is the VXLAN network type in OpenStack really scalable comparing with VLAN
or GRE? Or does the current OpenStack just provide functionality to handle
VXLAN header?

Please let me know good example about VXLAN usage, which can provide
scalability for multi-tenant on OpenStack. I'd like to know whether more
than 100000 tenants could be handled by VXLAN on the latest OpenStack
implementation or not.

Best regards

Byeong-Gi KIM

2014-09-18 11:20 GMT+09:00 George Mihaiescu <George.Mihaiescu at q9.com>:

>  The internal VLAD ID is indeed limited to 4096 but this internal tag
> number is used to isolate different neutron subnets, not tenants.
>
> A tenant could create 10 neutron networks each with its own subnet and
> then start 10 instances each attached to a separate net/subnet. If these
> instances would be scheduled on the same compute node then they would all
> use different internal VLAN IDs (locally unique to that node).
>
>
>
> Basically, you’re right that there is a built-in limitation of 4096
> instances attached to 4096 different Neutron net/subnets on a compute node,
> but it’s not realistic to actually start that many instances on a compute
> node.
>
>
>
> George
>
>
>
>
>  ------------------------------
>
> *From:* BYEONG-GI KIM [mailto:kimbyeonggi at gmail.com]
> *Sent:* Wednesday, September 17, 2014 8:47 PM
> *To:* openstack at lists.openstack.org
> *Subject:* [Openstack] Question about VXLAN support
>
>
>
> 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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