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From <>
Subject Re: Creating a Network inside a vpc which isnt attached to the routervm
Date Tue, 15 Aug 2017 12:05:58 GMT
Hi Dag,

thank you for your answer. As far as I know, the end user never has direct access to the virtual
router. I am not talking about adding a VLAN tag at the user VM, only at the VPR, where the
limit most likely comes into play when creating a number of tiers in a VPC.

We could do both: normal VMs require one interface per tier/network, which makes perfect sense.
The router however could use VLAN tags at VM level, which could remove the limitation of having
a maximum number of tiers connected to one VPC. It is only configured by CloudStack, the end
user does not have access to the VPR.


Am 15.08.17, 13:27 schrieb "Dag Sonstebo" <>:

    Hi Daniel,
    In theory that could work – but keep in mind we are working in a multi-tenant environment,
where guest isolation must be guaranteed, hence cannot ever be exposed to normal users. The
isolation method must be abstracted from the end user VMs – otherwise you would have a potential
security issue where someone could tag traffic from their VM with  someone else’s tag. Doing
tagging at VM level would also be a huge overhead.
    As a result we VLAN tag at the vSwitch or bridge level – which end users have no access
to – the flipside of the coin being that this requires separate NICs for each tier.
    Dag Sonstebo
    Cloud Architect
    On 15/08/2017, 11:07, "" <>
        we are hitting the same limitation, except that we can use 10 NICs on VMware.
        The fact that we also use the Private Gateway functionality addes another NIC, besides
the management and outside NIC which is present as well.
        I wonder that is the reason for one NIC per tier? Why not just use one outside NIC,
one management NIC and *one* NIC for the tiers, where the VLANs (or whatever isolation method
is used) is trunked, for example just using subinterfaces and dot1Q tags? This would eliminate
this limit for whatever hypervisor that supports trunk to it’s guests (I know for sure about
VMWare, not so much about the other hypervisors).
        Am 15.08.17, 10:52 schrieb "Dag Sonstebo" <>:
            Hi Dennis,
            Any tier or network which is accessible and part of a VPC requires an interface
on the VPC Virtual Router.
            What you can however do is create separate shared networks and connect these as
secondary networks to your VMs – these shared networks get their own VR.
            Dag Sonstebo
            Cloud Architect
            On 15/08/2017, 09:19, "Dennis Meyer" <> wrote:
                im using xenserver as hypervisor so im limited to 7 nic's / vm, so the
                router vm cant handle more than 7 nics which corresponds to 7 networks
                inside a vpc. I had created some networks for different drbd and corosync
                stuff, they dont need a gateway, dhcp and a router vm. How should a network
                offering look like which dont creates a network on the routervm but is
                accessible by the vpc?
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