Open Stack

Not sure if this is what you're looking for but...

For my private cloud in research environment we have a public provider
network available to all projects.

This is externally routed and has basically been in the same config
since Folsom (currently we're upto Mitaka).  It provides public ipv4
addresses. DHCP is done in neutron (of course) the lower portion of
the allocated subnet is excluded from the dynamic range.  We allow
users to register DNS names in this range (through pre-exisiting
custom, external IPAM tools) and to specify the fixed ip address when
launching VMs.

This network typically has 1k VMs running. We've assigned a /18 to
which is obviously overkill.

A few projects also have provider networks plumbed in to bridge they
legacy physical networks into OpenStack.  For these there's no dynamic
range and users must specify fixed ip, these are generally considered
"a bad idea" and were used to facilitate dumping VMs from old Xen
infrastructures into OpenStack with minimal changes.

These are old patterns I wouldn't necessarily suggest anyone
replicate, but they are the truth of my world...

-Jon

On Mon, May 22, 2017 at 12:47:01PM -0700, Chris Marino wrote:
:Hello operators, I will be talking about the new routed provider network
:<https://docs.openstack.org/ocata/networking-guide/config-routed-networks.html>
:features in OpenStack at a Meetup
:<https://www.meetup.com/openstack/events/239889735/>next week and would
:like to get a better sense of how provider networks are currently being
:used and if anyone has deployed routed provider networks?
:
:A typical L2 provider network is deployed as VLANs to every host. But
:curious to know how how many hosts or VMs an operator would allow on this
:network before you wanted to split into segments? Would you split hosts
:between VLANs, or trunk the VLANs to all hosts? How do you handle
:scheduling VMs across two provider networks?
:
:If you were to go with L3 provider networks, would it be L3 to the ToR, or
:L3 to the host?
:
:Are the new routed provider network features useful in their current form?
:
:Any experience you can share would be very helpful.
:CM
:
:
:ᐧ

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