[openstack-dev] [api][neutron][nova][Openstack-operators][interop] Time for a bikeshed - help me name types of networking

PACHECO, RODOLFO J rp2723 at att.com
Mon May 15 18:21:14 UTC 2017


The one missing aspect in this network model, is the ability to identify /categorize a VNF VM, that i.e. Is using SRIOV and only cares about VLAN’s
Such VM’s would not have IP Addresses in some cases, and wouldn’t be describable with the external/internal address labels.

I feel you need some other mechanism or tag to capture that type of server. Or at least be able to account for them. (no-external-ip / or external-vlan , or something)

It’s possible that the case I mention is what you refer to here “ Again, there are more complex combinations possible. For now this is 
    focused on the 80% case. I'm deliberately ignoring questions like vpn or 
    tricircle-style intra-cloud networks for now. “




Home/Office 732 5337671

On 5/14/17, 1:02 PM, "Monty Taylor" <mordred at inaugust.com> wrote:

    Hey all!
    I'm working on a proposal to formalize a cloud profile document. (we 
    keep and support these in os-client-config, but it's grown up ad-hoc and 
    is hard for other languages to consume -so we're going to rev it and try 
    to encode information in it more sanely) I need help in coming up with 
    names for some things that we can, if not all agree on, at least not 
    have pockets of violent dissent against.
    tl;dr: What do we name some enum values?
    First, some long-winded background
    == Background ==
    The profile document is where we keep information about a cloud that an 
    API consumer needs to know to effectively use the cloud - and is stored 
    in a machine readable manner so that libraries and tools (including but 
    hopefully not limited to shade) can make appropriate choices.
    Information in profiles is the information that's generally true for all 
    normal users. OpenStack is flexible, and some API consumers have 
    different access. That's fine - the cloud profiles are not for them. 
    Cloud profiles define the qualities about a cloud that end users can 
    safely expect to be true. Advanced use is never restricted by annotating 
    the general case.
    First off, we need to define two terms:
    "external" - an address that can be used for north-south communication 
    off the cloud
    "internal" - an address that can be used for east-west communication 
    with and only with other things on the same cloud
    Again, there are more complex combinations possible. For now this is 
    focused on the 80% case. I'm deliberately ignoring questions like vpn or 
    tricircle-style intra-cloud networks for now. If we can agree on an 
    outcome here - we can always come back and add words to describe more 
    ** Bikeshed #1 **
    Are "internal" and "external" ok with folks as terms for those two ideas?
    We need a term for each - if we prefer different terms, replacing their 
    use in the following is simple.
    == Booting Servers ==
    When booting a server, a typical user wants one of the following:
    - Give me a server with an external address
    - Give me a server with an internal address
    - Give me a server with both
    - Give me a server with very specific networking connections
    The fourth doesn't need any help - it's the current state of the world 
    today and is well served. It's the "I have a network I am aware of 
    and/or a pre-existing floating ip, etc and I want to use them". This is 
    not about those people - they're fine.
    Related to the first three cases, depending on how the cloud is 
    deployed, any of the following can be non-exclusively true:
    - External addresses are provided via Fixed IPs
    - External addresses are provided via Floating IPs
    - Internal addresses are provided via Fixed IPs
    - Internal addresses can be provided via Floating IPs
    - Users can create and define their own internal networks
    Additionally, External addresses can be IPv4 or IPv6
    == Proposal - complete with Unpainted Sheds ==
    I want to add information to the existing cloud profile telling the API 
    user which of the models above are available.
    The cloud profile will gain a field called "network-models" which will 
    contain one or more names from an enum of pre-defined models. Multiple 
    values can be listed, because some clouds provide more than one option.
    ** Bikeshed #2 **
    Anybody have a problem with the key name "network-models"?
    (Incidentally, the idea from this is borrowed from GCE's 
    "compute#accessConfig" [0] - although they only have one model in their 
    enum: "ONE_TO_ONE_NAT")
    In a perfect future world where we have per-service capabilities 
    discovery I'd love for such information to be exposed directly by 
    neutron. Therefore, I'd LOVE if we can at agree that the concepts are 
    concepts and on what to name them so that users who get the info from a 
    cloud profile today can get it from a discovery call in the future and 
    have some expectation that the terms carry the same meaning.
    Reminder - this is about the 80% case. Complex cases are already handled.
    ** Bikeshed #3 **
    What do we call the general concepts represented by fixed and floating 
    ips? Do we use the words "fixed" and "floating"? Do we instead try 
    something else, such as "direct" and "nat"?
    I have two proposals for the values in our enum:
    #1 - using fixed / floating
    #2 - using direct / nat
    Does anyone have strong feelings one way or the other?
    My personal preference is direct/nat. "floating" has a tendency to imply 
    different things to different people (just watch, we're going to have at 
    least one rabbit hole that will be an argument about the meaning of 
    floating ips) ... while anyone with a background in IT knows what "nat" 
    is. It's also a characteristic from a server/workload perspective that 
    is related to a choice the user might want to make:
      Does the workload need the server to know its own IP?
      Does the workload prefer to be behind NAT?
      Does the workload not care and just wants connectivity?
    On the other hand, "direct" isn't exactly a commonly used word in this 
    context. I asked a ton of people at the Summit last week and nobody 
    could come up with a better term for "IP that is configured inside of 
    the server's network stack". "non-natted", "attached", "routed" and 
    "normal" were all suggested. I'm not sure any of those are super-great - 
    so I'm proposing "direct" - but please if you have a better suggestion 
    please make it.
    == Maybe Examples will make it Clearer ==
    Some examples of how these would be applied in cloud profiles, based on 
    some public and private clouds. Using the direct/nat terms for the 
    examples- could just as easily get search/replaced:
       - ipv4-external-direct
       - ipv4-external-nat
       - ipv4-internal-direct
       - ipv6-direct
       - ipv4-external-nat
       - ipv4-internal-direct
       - ipv4-external-direct
       - ipv4-internal-direct
       - ipv6-direct
       - ipv4-external-direct
       - ipv6-direct
       - ipv4-external-direct
       - ipv4-internal-direct
    Having those available should allow for a user to express to a library 
    or framework such as shade or terraform:
    "get me a server with an external ipv4 using direct if it's available 
    and nat if not"
       create_server('my-server', external_network=True)
    "get me a server with an external ipv4 using nat if it's available but 
    direct is ok"
           'my-server', external_network=True,
           external_models=['ipv4-external-nat', 'ipv4-external-direct'])
    "get me a server with an external ipv4 using direct and fail if it's not 
           'my-server', external_network=True,
    "get me a server with only an internal ipv4 and please fail if that 
    isn't possible"
           'my-server', external_network=False, internal_network=True)
    == Follow up future - Capabilities Discovery ==
    This is WAY out of scope for right now, but here are some initial 
    thoughts about how the same values could be exposed from the API. It's 
    not necessary that we like this part - or that if we do that this API is 
    what we'd like. The important point would be that IF we decided to 
    expose this information via the API in the future that the same terms be 
    Here's a straw man of how the info _could_ be exposed in the future:
    1) In /capabilities (or whatever we call it)
    Whenever we add capabilities discovery, the models in the cloud-profile 
    could be one of the fields exposed:
    GET /capabilities.json
       "capabilities": {
         "network-models": {
    2) As information on networks themselves:
    GET /networks.json
       "networks": [
           "status": "ACTIVE",
           "name": "GATEWAY_NET_V6",
           "id": "54753d2c-0a58-4928-9b32-084c59dd20a6",
           "network-models": [
           "status": "ACTIVE",
           "name": "GATEWAY_NET",
           "id": "7004a83a-13d3-4dcd-8cf5-52af1ace4cae",
           "network-models": [
           "status": "ACTIVE",
           "name": "my-awesome-network",
           "id": "0be66687-9358-46cd-9093-9ce62cb4ece7",
           "network-models": [
    GET /networks
       "networks": [
           "status": "ACTIVE",
           "name": "public",
           "id": "6d6357ac-0f70-4afa-8bd7-c274cc4ea235",
           "network-models": [
    I'm not suggesting putting info on subnets, since one requests 
    connectivity from a network, not a subnet.
    networks with more than one "direct" model ("ipv4-external-direct", 
    "ipv4-internal-direct", "ipv6-direct") would communicate "you get all 
    the listed models". A network with a direct model AND a nat model 
    communicate that the network can be used as a target for direct booting 
    _and_ can be used as a source of NAT.
    It's worth noting that operators _could_ annotate their networks with 
    this information today using tags ... but since this is in service of 
    interoperability, just falling back on expecting operators to add some 
    specific strings to an otherwise free-form tags field seems like a thing 
    that would be messier to add to the Interop Guidelines in the future 
    compared to a strict set of pre-defined enum values with their own 
    non-overloaded field.
    == Conclusion ==
    Ok. I know that's yet-another billion-line pile of text from me. Sorry 
    about that. In case you've forgotten the bikeshed topics at this point:
    * Internal and External OK?
    * network-models OK?
    * fixed/floating vs. direct/nat vs. something else?
    Comments, feedback, concerns, raves and rants are all welcome.
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