Description:

something wrong with ipv6 addr for ICMP "needs fragmentation" message when SNAT is configured

it only failed in distributed gateway port mode and passed in gateway mode

version:

ovn24.09-24.09.0-beta.23.el9fdp.x86_64

steps:

systemctl start openvswitch
systemctl start ovn-northd
ovn-nbctl set-connection ptcp:6641
ovn-sbctl set-connection ptcp:6642
ovs-vsctl set open . external_ids:system-id=hv1 external_ids:ovn-remote=tcp:127.0.0.1:6642 external_ids:ovn-encap-type=geneve external_ids:ovn-encap-ip=127.0.0.1
systemctl restart ovn-controller

ovs-vsctl add-br br-ext
ovs-vsctl set Open_vSwitch . external-ids:ovn-bridge-mappings=phynet:br-ext

ovn-nbctl lr-add lr
ovn-nbctl ls-add internal
ovn-nbctl ls-add public

ovn-nbctl lrp-add lr lr-pub 00:00:01:01:02:03 192.168.1.1/24 2001::1/64
ovn-nbctl lsp-add public pub-lr -- set Logical_Switch_Port pub-lr \
type=router options:router-port=lr-pub addresses=\"00:00:01:01:02:03\"

ovn-nbctl lrp-add lr lr-internal 00:00:01:01:02:04 172.16.1.1/24 3010::1/64
ovn-nbctl lsp-add internal internal-lr -- set Logical_Switch_Port internal-lr \
type=router options:router-port=lr-internal addresses=\"00:00:01:01:02:04\"

ovn-nbctl lsp-add public ln_port \
-- lsp-set-addresses ln_port unknown \
-- lsp-set-type ln_port localnet \
-- lsp-set-options ln_port network_name=phynet

ovn-nbctl lsp-add internal client \
-- lsp-set-addresses client "f0:00:0f:01:02:03 172.16.1.2 3010::2"
ovn-nbctl lrp-set-gateway-chassis lr-pub hv1
ovn-nbctl set logical_router_port lr-internal options:gateway_mtu=1300

ovs-vsctl add-port br-int client -- set interface client type=internal external_ids:iface-id=client
ip netns add client
ip link set client netns client
ip netns exec client ip link set client address f0:00:0f:01:02:03
ip netns exec client ip addr add 172.16.1.2/24 dev client
ip netns exec client ip addr add 3010::2/64 dev client
ip netns exec client ip link set client up
ip netns exec client ip route add default via 172.16.1.1
ip netns exec client ip -6 route add default via 3010::1

ovs-vsctl add-port br-ext server -- set interface server type=internal
ip netns add server
ip link set server netns server
ip netns exec server ip link set server up
ip netns exec server ip addr add 192.168.1.2/24 dev server
ip netns exec server ip addr add 2001::2/64 dev server

ovn-nbctl lr-nat-add lr snat 2001::1 3010::2/64
ovn-nbctl lr-nat-add lr snat 192.168.1.1 172.16.1.2/24
ip netns exec client ping 192.168.1.2 -c 1
ip netns exec client ping 192.168.1.2 -c 1 -s 1400
ip netns exec client ping 192.168.1.2 -c 1 -s 1400 -W 2
ip netns exec client ping 192.168.1.2 -c 1 -s 1400 -W 2

ip netns exec client ping6 2001::2 -c 1
ip netns exec client ping6 2001::2 -c 1 -s 1400
ip netns exec client ping6 2001::2 -c 1 -s 1400 -W 2
ip netns exec client ping6 2001::2 -c 1 -s 1400 -W 2 

expected result:
last ping6 passed

actual result:

last ping6 failed

other info:

[root@dell-per740-33 FDP-39]# rpm -qa | grep -E "openvswitch3.3|ovn"                     
openvswitch3.3-3.3.0-45.el9fdp.x86_64                                                    
python3-openvswitch3.3-3.3.0-45.el9fdp.x86_64                                            
ovn24.09-24.09.0-beta.23.el9fdp.x86_64                                                   
ovn24.09-central-24.09.0-beta.23.el9fdp.x86_64                                           
ovn24.09-host-24.09.0-beta.23.el9fdp.x86_64

+ ip netns exec client ping6 2001::2 -c 1                                                
PING 2001::2(2001::2) 56 data bytes
64 bytes from 2001::2: icmp_seq=1 ttl=63 time=6.69 ms                                    

— 2001::2 ping statistics —                                                          
1 packets transmitted, 1 received, 0% packet loss, time 0ms                              
rtt min/avg/max/mdev = 6.686/6.686/6.686/0.000 ms                                        
+ ip netns exec client ping6 2001::2 -c 1 -s 1400
PING 2001::2(2001::2) 1400 data bytes
From 3010::1 icmp_seq=1 Packet too big: mtu=1300                                         

— 2001::2 ping statistics —
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms                 
                                                                                         
+ ip netns exec client ping6 2001::2 -c 1 -s 1400 -W 2                                   
PING 2001::2(2001::2) 1400 data bytes                                                    
                                                                                         
— 2001::2 ping statistics —                                                          
1 packets transmitted, 0 received, 100% packet loss, time 0ms                            
                                                                                         
+ ip netns exec client ping6 2001::2 -c 1 -s 1400 -W 2                                   
PING 2001::2(2001::2) 1400 data bytes                                                    
                                                                                         
— 2001::2 ping statistics —                                                          
1 packets transmitted, 0 received, 100% packet loss, time 0ms

<=== ping6 failed

the issue didn't exist on ovn24.03-24.03.2-32:

[root@dell-per740-33 FDP-39]# rpm -qa | grep -E "openvswitch3.3|ovn"                     
openvswitch3.3-3.3.0-45.el9fdp.x86_64                                                    
python3-openvswitch3.3-3.3.0-45.el9fdp.x86_64                                            
ovn24.03-24.03.2-32.el9fdp.x86_64                                                        
ovn24.03-central-24.03.2-32.el9fdp.x86_64                                                
ovn24.03-host-24.03.2-32.el9fdp.x86_64

+ ip netns exec client ping6 2001::2 -c 1
PING 2001::2(2001::2) 56 data bytes
64 bytes from 2001::2: icmp_seq=1 ttl=63 time=6.29 ms

— 2001::2 ping statistics —                                                          
1 packets transmitted, 1 received, 0% packet loss, time 0ms                              
rtt min/avg/max/mdev = 6.286/6.286/6.286/0.000 ms
+ ip netns exec client ping6 2001::2 -c 1 -s 1400                                        
PING 2001::2(2001::2) 1400 data bytes
From 3010::1 icmp_seq=1 Packet too big: mtu=1300                                         

— 2001::2 ping statistics —                                                          
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms                 
                                                                                         
+ ip netns exec client ping6 2001::2 -c 1 -s 1400 -W 2                                   
PING 2001::2(2001::2) 1400 data bytes                                                    
                                                                                         
— 2001::2 ping statistics —                                                          
1 packets transmitted, 0 received, 100% packet loss, time 0ms                            
                                                                                         
+ ip netns exec client ping6 2001::2 -c 1 -s 1400 -W 2                                   
PING 2001::2(2001::2) 1400 data bytes                                                    
1408 bytes from 2001::2: icmp_seq=1 ttl=63 time=1.29 ms                                  
                                                                                         
— 2001::2 ping statistics —                                                          
1 packets transmitted, 1 received, 0% packet loss, time 0ms                              
rtt min/avg/max/mdev = 1.287/1.287/1.287/0.000 ms

<=== ping6 passed