Open Stack

You typically enable DHCP on networks where you intend to put VMs. Neutron routers don’t rely on DHCP to obtain their IP. If you enable DHCP on the external network, and your intention if only to connect routers to it, those DHCP server(s) Neutron creates will still each consume an IP address, reducing the total number of IPs available for use as floating IPs.

-- 
James Denton
Network Architect
Rackspace Private Cloud
james.denton at rackspace.com


On 9/2/16, 1:26 PM, "Satish Patel" <satish.txt at gmail.com> wrote:

    Thanks James,
    
    I didn't understand your following statement.
    
    "You may want to refrain from enabling DHCP on that subnet as well,
    otherwise they will each grab an address as well."
    
    Could you give me example or explain what does that means?
    
    On Fri, Sep 2, 2016 at 1:53 PM, James Denton <james.denton at rackspace.com> wrote:
    > Hi Satish,
    >
    > You can create multiple non-contiguous allocation pools for the external (floating) network, even as small as a single IP address. Keep in mind that the Neutron router will take an IP address from this pool for its ‘qg’ interface. You may want to refrain from enabling DHCP on that subnet as well, otherwise they will each grab an address as well.
    >
    > James
    >
    > On 9/2/16, 10:34 AM, "Satish Patel" <satish.txt at gmail.com> wrote:
    >
    >     Its very weird requirement, stay with me to explain.
    >
    >     We have /24 public IP pool which we are using since long time and we
    >     cherry picked IP address from that pool so they are not in sequence :(
    >
    >     Now we have openstack and i want to give some floating IP to openstack
    >     but because of non-sequence range how do i give individual IP address
    >     to floating pool in VLAN?
    >
    >     In single VLAN 10 net how do i put individual IP in subnet?
    >
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