Hi all,

 

We have been looking at building some routed provider networks, following this documentation: https://docs.openstack.org/neutron/latest/admin/config-routed-networks.html

 

In this scenario we have 4 racks, and have defined physnets for each rack and assigned SRIOV interfaces for each.     We then have created a multisegment network, with a segment associated with each physnet.    We get the expected resource provider in placement containing only these hypervisors.

 

When scheduling instances onto this network, the allocation candidates are any hypervisors in racks 1-4 (openstack filters the hypervisors using the aggregates for each segment that neutron creates).
However, during instance build the pci device request sent to nova-compute always contains the physnet of the same segment.

 

Debugging the builds, we ended up here: https://opendev.org/openstack/nova/src/branch/master/nova/network/neutron.py#L2226, with:

# TODO(vladikr): Additional work will be required to handle the

# case of multiple vlan segments associated with different

# physical networks.

 

Which originates from this commit: https://opendev.org/openstack/nova/commit/b9d9d96a407db5a2adde3aed81e61cc9589c291a

 

This suggests that despite the documentation describing using multiple VLAN backed segments in this fashion, this has never worked?   Or are we missing something?  Has anyone successfully used routed provider networks?