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Gap discovered in a deep dive discussion: Homing happens at the VNF level, while we Homing need to map flavors at the granularity of VFModules.
Collecting the discussion from multiple threads [need to organize this better once we reach a workable solution]
The current data model in AAI looks like the following:
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(iii) requires the creation of multiple flavors that captures the different combinations of capabilities, which is a combinatorial problem.
- One NSD (Network Service Descriptor) can contain multiple VNFs.
- Each VNF can contain
- Multiple VDUs (VNFCs)
- Internal Virtual Links
- Internal Connection points
- Connection points to External Links.
- Each VDU (VNFC) is normally realized as one VM or set of scale-out VMs.
Each VDU is defined with HPA properties that are required for that VDU.
An example:
Let us say that a NSD has 2 VNFs. Each VNF has 4 VDUs.
I believe OOF is passed with NSD by SO or VF-C.
OOF is expected to determine right region and flavor to use for each VDU. In above example, I would assume that OOF returns total of 8 regions and one flavor for each region (8 flavors) back to SO.
Having said that, many times, a VNF consists only one VNFC (one VDU). At least I did not see any real deployment example where a VNF contains multiple VNFCs (VDUs). Hence, people tend to equate VNF with VNFC (VDU). But, TOSCA NFV specification do have ability to represent a VNF with multiple VDUs.
In any case, it is good for OOF to assume that a VNF contains multiple VDUs.
HPA feature set filter is for each VDU. So is, distance filter.
But affinity, anti-affinity are at the scope of VNF and NSD.
Typical affinity/anti-affinity rules are as follows:
- Across VDUs of VNF (Few VDUs of VNF be on the same compute node, or in the same rack or at the edge in case of affinity rules or separately in various compute nodes, various racks or edges).
- Across VNFs of NSD ( Few VNFs of NSD in the same compute, rack or edge in case of affinity or separately in case of affinity rules, or in different places in case of anti-affinity rules).
That is why, I think SO needs to pass massaged NSD with VNFs and VDUs of VNFs together for placement decisions based on affinity/anti-affinity policy rules. Passing the VNF by SO is not good enough if OOF intends to make placement decisions based on affinity and anti-affinity rules.
Follow up discussion on the above from 02/19/2018:
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