[ovs-dev] [ovn] howto? L3 support in HW VTEP

[Vladislav Odintsov]

Hi all,

I’m trying to implement support for L3 routing between OVN and HW VTEP devices.
In my setup I use Cumulus Linux-managed Mellanox SN2000 switches.
Current L2 functionality in this setup works well: ovn-controller-vtep and a
small python service on the switch (which installs necessary mcast_macs entries
in switch fdb, since Cumulus Linux vtep support is limited to service_node
replication mode).

My logical topology for L3 setup:

2 logical_switches connected to same logical_router:
Net1: 192.168.1.0/24, gw ip (lrouter): 192.168.1.1, VM 192.168.1.2
Net2: 192.168.2.0/24, gw ip (lrouter): 192.168.2.1, Physical host 192.168.2.2

Net1 has attached logical_switch_port with type vtep. In Net2 there is a VM
(192.168.2.2/24), which needs ip connectivity to physical host (192.168.1.2/24)
connected to HW VTEP Mellanox switch over vtep lport from Net1.

For Net1’s LRP (192.168.1.1) I’ve created chassis_redirect port_binding to some
Chassis and patched controller-step code so that such CR LRP’s MAC is also
added to Ucast_Macs_Remote vtep table.
Traffic from ovn-host to vtep (192.168.1.2 to 192.168.2.2) passes well, but in
reverse direction physical server sends to all ovn-hosts ARP request Who has
192.168.2.1? tell 192.168.2.2. But no answer. If I manually configure arp on
this physical server, connectivity between VM and physical host works well!

Now I’m stuck with arp resolution for LRP from VTEP lport from OVN side. Can
somebody give an idea how to make ovn-controllers answer such ARP request?

Thanks.

Regards,
Vladislav Odintsov