Bug 1864277

Summary:	[RFE] [P1] OVN SR-IOV external port for DHCP services is not Nova/Neutron AZ aware
Product:	Red Hat OpenStack	Reporter:	Anita Tragler <atragler>
Component:	openstack-neutron	Assignee:	Lucas Alvares Gomes <lmartins>
Status:	MODIFIED ---	QA Contact:	Eran Kuris <ekuris>
Severity:	high	Docs Contact:
Priority:	high
Version:	17.1 (Wallaby)	CC:	bcafarel, chrisw, dalvarez, gurpsing, lmartins, scohen, skaplons
Target Milestone:	ga	Keywords:	FutureFeature
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	openstack-neutron-18.5.1-1.20221028211119.93e7091.el9ost	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	2119064 (view as bug list)		Environment:
Last Closed:		Type:	Bug
Regression:	---	Mount Type:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2119064

Description Anita Tragler 2020-08-03 18:29:38 UTC

Description of problem:

For Edge DCN usecase with SR-IOV + DHCP service,  each Edge site is in a separate Nova/Neutron AZs and we need site-local DHCP services

This BZ needs to be verified with Routed Provider Networks or Provider networks on SR-IOV requiring DHCP services in a Nova/Neutron Availability Zone
This is a typical Edge DCN deployment for Telco
This is currently supported with ML2/OVS using Routed Provider Networks on SR-IOV with DHCP, need equivalent support for OVN

Similar scenario may also be needed for Enterprise Spine-leaf deployments with provider networks on SR-IOV in Nova AZs

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Comment 6 Gurpreet Singh 2022-09-02 15:31:33 UTC

Is this an availability issue for DHCP services if port is on different AZ? If yes, then it is a blocker and we need to address it in 17.1. Currently marking it as high. Please confirm if that is indeed the case.

Comment 7 Lucas Alvares Gomes 2022-09-05 07:29:49 UTC

(In reply to Gurpreet Singh from comment #6)
> Is this an availability issue for DHCP services if port is on different AZ?
> If yes, then it is a blocker and we need to address it in 17.1. Currently
> marking it as high. Please confirm if that is indeed the case.

Hi,

For normal ports, DHCP is not an issue with OVN because the ovn-controller running on the compute node handles DHCP for the VMs.

For SR-IOV ports it could be an issue because in ML2/OVN are SR-IOV ports are "external" ports scheduled on a separated node and the problem that this BZ fixes is actually making sure that these SR-IOV ports are scheduled onto the nodes belonging to the requested AZs. If the AZs are isolated from each other and we do not have the fix for this BZ in place, the SR-IOV ports will not be co-located within the same AZ and could end up somewhere not accessible.

As comment #4 states, this work [0] has been completed upstream, but will need backporting. The patch is somewhat complex because it touches many files, it's probably feasible for 17.X but I am not sure about 16.X backport.

[0] https://review.opendev.org/c/openstack/neutron/+/762550

Cheers,
Lucas