Public bug reported: We have a Xena deployment based on Linux bridge networking, with a mix of Neutron managed VXLAN, and routed/L3 provider networks.
neutron-dhcp-agent services are deployed to a set of network nodes in order to serve the VXLAN networks. These services are also deployed to a subset of compute nodes which are the only hosts with access to the routed provider networks. We would like the network nodes to be used in preference to the compute nodes when DHCP instances are created against VXLAN tenant networks. Having written a patch to achieve this (modifying the DHCP scheduler filtering - https://github.com/bbc/neutron/commit/54b135e1412d83acb68995a71ed864118162ab01), this works correctly when networks are first created. However, if a given network has a DHCP agent/port removed at any point and a DHCP service on one of the compute nodes is subsequently restarted, these filters are ignored and the compute node takes over this responsibility. As far as I can tell, when the DHCP agent service starts up it requests details of the active networks and seeing a network it can reach which doesn't have the correct number of agents deployed, takes over this responsibility, bypassing the scheduling filters. The existing filters which ensure a DHCP service has physical access to a given L3 segment appear to work because there is a second implementation of that filtering in https://github.com/openstack/neutron/blob/master/neutron/api/rpc/handlers/dhcp_rpc.py#L212. I'd appreciate a second opinion on whether by making changes to the DHCP scheduler filtering only, it should be reasonable to expect its rules to apply at times after initial network/subnet creation? If there is an architectural reason the filters don't get re-used, would my best option be to add further patching in dhcp_rpc to achieve the desired behaviour? Thanks ** Affects: neutron Importance: Undecided Status: New -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to neutron. https://bugs.launchpad.net/bugs/1964765 Title: DHCP agent scheduler filtering ignored when agent service restarted Status in neutron: New Bug description: We have a Xena deployment based on Linux bridge networking, with a mix of Neutron managed VXLAN, and routed/L3 provider networks. neutron-dhcp-agent services are deployed to a set of network nodes in order to serve the VXLAN networks. These services are also deployed to a subset of compute nodes which are the only hosts with access to the routed provider networks. We would like the network nodes to be used in preference to the compute nodes when DHCP instances are created against VXLAN tenant networks. Having written a patch to achieve this (modifying the DHCP scheduler filtering - https://github.com/bbc/neutron/commit/54b135e1412d83acb68995a71ed864118162ab01), this works correctly when networks are first created. However, if a given network has a DHCP agent/port removed at any point and a DHCP service on one of the compute nodes is subsequently restarted, these filters are ignored and the compute node takes over this responsibility. As far as I can tell, when the DHCP agent service starts up it requests details of the active networks and seeing a network it can reach which doesn't have the correct number of agents deployed, takes over this responsibility, bypassing the scheduling filters. The existing filters which ensure a DHCP service has physical access to a given L3 segment appear to work because there is a second implementation of that filtering in https://github.com/openstack/neutron/blob/master/neutron/api/rpc/handlers/dhcp_rpc.py#L212. I'd appreciate a second opinion on whether by making changes to the DHCP scheduler filtering only, it should be reasonable to expect its rules to apply at times after initial network/subnet creation? If there is an architectural reason the filters don't get re-used, would my best option be to add further patching in dhcp_rpc to achieve the desired behaviour? Thanks To manage notifications about this bug go to: https://bugs.launchpad.net/neutron/+bug/1964765/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
