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From Sanjeev Neelarapu <>
Subject RE: Public IPs on Guest VMs within CloudStack 4.2.0
Date Fri, 18 Oct 2013 05:21:44 GMT

If you are creating isolated network with your /27 cidr and deploying vm in that , default
gateway on the vm will always points to ip address configured on the virtual routers guest
interface. So for the vms to point to the gateway in /27 cidr, create a shared network and
deploy vm in that.


-----Original Message-----
From: Bryan Manske [] 
Sent: Friday, October 18, 2013 1:20 AM
Subject: Public IPs on Guest VMs within CloudStack 4.2.0


Now I'm curious about public IPs on Guest VMs within CloudStack 4.2.0.

I have one IPv4 /27 for Public IPs and that's working fine.  Now what I want to do is assign
a live IP address from another /27 to a Guest VM, which appears to work but can't actually
touch the default gateway.

So here's the rub: The default gateway is actually provided as a virtual IP on two VRRP nodes
(for A/B redundancy) by my upstream provider.  I can ping the two VRRP routers, I can see
the VM has the proper IP address, netmask, and default gateway; and I can configure the VM
with a proper IP config which never finds the default gateway IP.  The arp cache sees the
local MAC address and incomplete for the gateway.

So now I'm thinking; according to cloudstack, is the default gateway plumbed on a virtual
router?  If so, how does THAT route out to the world?

I also have a /64 of IPv6 space, /96 of which I have configured in a network offering which
has the same upstream infrastructure situation.  Same lack of functionality there.

So how do I configure my Guest real IP netblocks?  Is it okay to be looking for a default
gateway IP on a my provider's core router or do I need to have them statically route that
netblock to something like the cloudstack management host?

Of course I could also have the network offering wrong or incomplete.

Any thoughts or pointers to documentation would be appreciated.

I can tell I'm making progress because I keep dealing with progressively higher level errors.


Bryan Manske

"Earnest falsehoods left unchallenged risk being accepted as fact."
 -- Monty "xiphmont" Montgomery - Xiph Foundation, on the Ogg format

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