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From "Marcus Sorensen (JIRA)" <>
Subject [jira] [Commented] (CLOUDSTACK-4967) vxlan doesn't scale
Date Tue, 29 Oct 2013 06:59:31 GMT


Marcus Sorensen commented on CLOUDSTACK-4967:

I created two guest networks, one as a vlan isolation type, the other a vxlan isolation type.
The vlan isolation type has traffic label 'cloudbr0', on physical eth0, and the vxlan has
traffic label 'eth2' on physical network eth2.

This patch would still allow multiple guest networks to use vxlan isolation, just not the
same VNI numbers. It doesn't enforce this though

Here they are running together:

root@devcloud-kvm-u:~# brctl show
bridge name	bridge id		STP enabled	interfaces
breth0-3905		8000.000c29d82947	no		eth0.3905
brvx-1213043		8000.a6e6026f7fbb	no		vnet9
brvx-1589169		8000.663d4e875e78	no		vnet10
cloud0		8000.fe00a9fe0069	no		vnet0
cloudbr0		8000.000c29d82947	no		eth0
cloudbr1		8000.000c29d82951	no		eth1

> vxlan doesn't scale
> -------------------
>                 Key: CLOUDSTACK-4967
>                 URL:
>             Project: CloudStack
>          Issue Type: Bug
>      Security Level: Public(Anyone can view this level - this is the default.) 
>          Components: KVM
>    Affects Versions: 4.3.0
>            Reporter: Marcus Sorensen
>            Assignee: Yoshikazu Nojima
>             Fix For: 4.3.0
> Failed to create vnet 987529:     inet
brd scope global cloudbr0Error: an inet prefix is expected rather than "239.15.3857.137".Error
> It looks like the vxlan implementation doesn't scale correctly with vxlan's capabilities.
The VNI is supposed to be up to 24 bits (16777216), it should be possible to use high VNI
numbers. The script '' seems to do this:
> local mcastGrp="239.$(( $vxlanId >> 16 % 256 )).$(( $vxlanId >> 8 % 256 )).$((
$vxlanId % 256 ))"
> $vlanid >> 8 %256 (and similar) may need to be ($vxlanId >> 8) % 256
> On a less important note, I should point out that the bridge naming convention will break
in certain rare situations. The max size of a bridge device name is 15 characters. For bond
devices, a VNI above 10 million will not fit, e.g. "brbond0-16000000", or ethernet devices
above 10 "breth10-16000000".  However, these may be quite rare, and changing the naming convention
as we found in 4.2 is a bit painful if it can't be done in a backward compatible way. My first
thought was to have vxlan and vxlan only use hex for it's VNI, that might be ok since it's
never been released yet.

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