[ovs-discuss] OVN Dynamic Routing

Ankur Sharma ankur.sharma at nutanix.com
Sat Jan 9 04:35:11 UTC 2021


Hi Daniel,

Glad to see your interest and queries. Please see responses below:


Q1) Who is responsible for creating the VTEP endpoints on each hypervisor? Are they assumed to be created in advance or somehow this solution will take care of it? If the latter, how will it work and how will 'ovn-routing' know the addresses of the endpoints? OVN VTEP gateways?

[ANKUR]: VTEP information is expected to be added out of band. For example, in our case the external gateway VTEP endpoint is added as a chassis by the management plane.


2) In the diagram at [0], what's the 'MAC ROUTER'? Is this OVN Logical Router connected to a Logical Switch with a localnet port and this MAC address corresponds to such port in the router? Or it would be the MAC address of '10.0.0.1'. What if two VMs in the same LS reside on different hypervisors, would you still advertise the same MAC but use a different VNI?

With OVN routers being distributed we'd have the same MAC address advertised on multiple HVs and we need to use different VNIs to distinguish them, right?
[ANKUR]: MAC ROUTER is the former, i.e OVN logical router connected to transit logical switch (please note that for NS connectivity in this case logical switch need not have localnet port, since we are not converting the packet to a VLAN packet). For all the VMs behind the logical router the advertised VNI is same and it is that of transit logical switch.

Transit logical switch is the switch that connects OVN logical router with external router.



3) If two OVN VMs want to reach each other, it will still use the Geneve overlay right? This whole solution is mainly for incoming traffic or I'm missing something?
[ANKUR]: Yes, now the workflow is that for EW traffic it is regular geneve encap and for NS instead of converting the packet to VLAN we forward it to external gateway using VXLAN and hence remove the requirement of a gateway chassis for NO NAT Cases.


Please feel free to let us know, if you have further queries.


Regards,
Ankur
________________________________
From: Greg Smith <greg at nutanix.com>
Sent: Thursday, January 7, 2021 8:38 AM
To: Daniel Alvarez Sanchez <dalvarez at redhat.com>; Ankur Sharma <ankur.sharma at nutanix.com>; Greg A. Smith <gasmith at nutanix.com>
Cc: Frode Nordahl <frode.nordahl at canonical.com>; ovs-discuss <ovs-discuss at openvswitch.org>
Subject: Re: [ovs-discuss] OVN Dynamic Routing


+ Greg A Smith



From: Daniel Alvarez Sanchez <dalvarez at redhat.com>
Date: Thursday, January 7, 2021 at 4:17 AM
To: Ankur Sharma <ankur.sharma at nutanix.com>
Cc: Frode Nordahl <frode.nordahl at canonical.com>, Greg Smith <greg at nutanix.com>, ovs-discuss <ovs-discuss at openvswitch.org>
Subject: Re: [ovs-discuss] OVN Dynamic Routing



Thanks Ankur, all for the presentation and slides.



If I may, I have a some questions regarding the proposed solution:



1) Who is responsible for creating the VTEP endpoints on each hypervisor? Are they assumed to be created in advance or somehow this solution will take care of it? If the latter, how will it work and how will 'ovn-routing' know the addresses of the endpoints? OVN VTEP gateways?



2) In the diagram at [0], what's the 'MAC ROUTER'? Is this OVN Logical Router connected to a Logical Switch with a localnet port and this MAC address corresponds to such port in the router? Or it would be the MAC address of '10.0.0.1'. What if two VMs in the same LS reside on different hypervisors, would you still advertise the same MAC but use a different VNI?

With OVN routers being distributed we'd have the same MAC address advertised on multiple HVs and we need to use different VNIs to distinguish them, right?



3) If two OVN VMs want to reach each other, it will still use the Geneve overlay right? This whole solution is mainly for incoming traffic or I'm missing something?



I'm sorry if the questions are a bit blurry but I guess that after reviewing the slides and recording I didn't quite grasp it :)



Thanks a lot in advance!

daniel



[0] https://youtu.be/9DL8M1d4xLY?t=330 [youtu.be]<https://urldefense.proofpoint.com/v2/url?u=https-3A__youtu.be_9DL8M1d4xLY-3Ft-3D330&d=DwMFaQ&c=s883GpUCOChKOHiocYtGcg&r=l2KqK5U87xc8UBeIEnhlhA&m=SRMQBULQJkV-FCkQL3j8jKJG7VsJvDJLM3fREJa0ymk&s=L4hURaD1nuVUyZhtTJViZPdXqd7YDychGkHlRuJVkh8&e=>





On Mon, Dec 14, 2020 at 8:25 PM Ankur Sharma <ankur.sharma at nutanix.com<mailto:ankur.sharma at nutanix.com>> wrote:

Hi Frode,

Glad to see your message.
Yes, while we started with EVPN as our main use case, we agree that it is more of a generic dynamic routing capability in OVN.

Sure, we will kickstart the discussions around this on mailing list as well.


Thanks

Regards,
Ankur

________________________________

From: Frode Nordahl <frode.nordahl at canonical.com<mailto:frode.nordahl at canonical.com>>
Sent: Thursday, December 10, 2020 1:10 AM
To: Ankur Sharma <ankur.sharma at nutanix.com<mailto:ankur.sharma at nutanix.com>>
Cc: Greg Smith <greg at nutanix.com<mailto:greg at nutanix.com>>; ovs-discuss <ovs-discuss at openvswitch.org<mailto:ovs-discuss at openvswitch.org>>
Subject: OVN Dynamic Routing



Hello, Ankur, Greg, All,

Thank you for sharing your view on dynamic routing support for OVN
during OVSCON 2020 [0].

I believe this is a topic that interests multiple parties in the
community, and it applies to multiple topologies/use cases, not just
EVPN.

Would you be interested in presenting and discussing the proposed
design on the mailing list?

0: https://urldefense.proofpoint.com/v2/url?u=https-3A__www.openvswitch.org_support_ovscon2020_&d=DwIBaQ&c=s883GpUCOChKOHiocYtGcg&r=mZwX9gFQgeJHzTg-68aCJgsODyUEVsHGFOfL90J6MJY&m=3HUT7aQXAsSImmITSraoqdZ6mWcRxUtwVRKAfH3ygQA&s=Xzze2S3f7Rstp66gRz7MSuTGvGltr3t8uxyx5M3R8og&e=

--
Frode Nordahl

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