ovn-bgp-agent

Bug #2017889
Comment #9

Comment 9 for bug 2017889

Revision history for this message

Maximilian Sesterhenn (msnatepg) wrote on 2023-05-22:

ltomasbo:
So you mean the BGP driver does not properly work for VM IPs on the provider network for IPv6?

msnatepg:
Exactly. In my opinion we need L2 resolution in both directions for any kind of communication.
For incoming packets that's working, but we need the same for outgoing packets.
With IPv4, the ARP proxy solves this as it replies to each request with its own MAC, for IPv6 we have to configure each IP explicitly.

ltomasbo:
I'm pretty sure we have some tests that cover the ping from external to VM on the provider with ipv6

msnatepg:
I wonder from where the ICMPv6 NS/NA messages gets answered in your environment. Can you verify that this is working for you?
It does not work in my lab and I would otherwise propose extending networking-bgpvpn to add the gateway of the network to external_ids so that we can add a proxy configuration for that.

I captured whats happening on my compute node (this is captured using the modified EVPN driver), you can see the packet traversing all the interfaces, but the NS messages are unanswered because the proxy_ndp has no configuration to proxy GW:

listening on any, link-type LINUX_SLL2 (Linux cooked v2), snapshot length 262144 bytes
13:24:09.567235 vxlan-12 In IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.567248 br-12 In IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.567262 veth-vrf-12 Out IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.567267 veth-ovs-12 P IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.567853 tapaa267af3-b2 Out IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.568361 tapaa267af3-b2 M IP6 INSTANCE_IP > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has GW, length 32
13:24:09.568621 veth-ovs-12 Out IP6 INSTANCE_IP > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has GW, length 32
13:24:09.568625 veth-vrf-12 In IP6 INSTANCE_IP > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has GW, length 32

ltomasbo: 
So you mean the BGP driver does not properly work for VM IPs on the provider network for IPv6?

msnatepg: 
Exactly. In my opinion we need L2 resolution in both directions for any kind of communication. 
For incoming packets that's working, but we need the same for outgoing packets. 
With IPv4, the ARP proxy solves this as it replies to each request with its own MAC, for IPv6 we have to configure each IP explicitly.

ltomasbo:
I'm pretty sure we have some tests that cover the ping from external to VM on the provider with ipv6

listening on any, link-type LINUX_SLL2 (Linux cooked v2), snapshot length 262144 bytes
13:24:09.567235 vxlan-12 In  IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.567248 br-12 In  IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.567262 veth-vrf-12 Out IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.567267 veth-ovs-12 P   IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.567853 tapaa267af3-b2 Out IP6 SRC > INSTANCE_IP: ICMP6, echo request, id 5, seq 1, length 64
13:24:09.568361 tapaa267af3-b2 M   IP6 INSTANCE_IP > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has GW, length 32
13:24:09.568621 veth-ovs-12 Out IP6 INSTANCE_IP > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has GW, length 32
13:24:09.568625 veth-vrf-12 In  IP6 INSTANCE_IP > ff02::1:ff00:1: ICMP6, neighbor solicitation, who has GW, length 32