Without an OMR prefix, how can the application of otbr access other devices on the Thread network via UDP?

[jinpeng1989]

Without the OMR prefix, the device has no OMR address, which address should I use? I tested the ML-EID address, the address is pingable. However, no response packet was received when I accessed the device using UDP. The otbr-agent does not route the response packet to the host of Thread Border Route. Why is result different between the ICMP and UDP?

[jinpeng1989]

Networkkey: 2dc2cb606691d85f2261ef5fe76a2746
Wireshark:
udp_unreadchable_mleid.zip

Test instruction:

root@KNBA5F000300:~# ot-ctl prefix meshlocal
fd31:8f54:8c96:326d::/64
Done
root@KNBA5F000300:~# ot-ctl prefix
fda6:54a6:89f3:1::/64 paos low b000
Done
root@KNBA5F000300:~# ip -6 route
fd31:8f54:8c96:326d::/64 dev wpan0  metric 256 
fd8d:7059:cff4::/64 dev br-lan  metric 1024 
unreachable fd8d:7059:cff4::/48 dev lo  metric 2147483647  error -113
fda6:54a6:89f3:1::/64 dev wpan0  metric 256 
fdef:ae77:a044:3043::/64 dev eth0  metric 256 
unreachable fdef:ae77:a044:3043::/64 dev lo  metric 2147483647  error -113
fe80::/64 dev eth0  metric 256 
fe80::/64 dev br-lan  metric 256 
fe80::/64 dev wpan0  metric 256 
fe80::/64 dev wlan0  metric 256 
anycast fd31:8f54:8c96:326d:: dev wpan0  metric 0 
anycast fd8d:7059:cff4:: dev br-lan  metric 0 
anycast fda6:54a6:89f3:1:: dev wpan0  metric 0 
anycast fdef:ae77:a044:3043:: dev eth0  metric 0 
anycast fe80:: dev eth0  metric 0 
anycast fe80:: dev br-lan  metric 0 
anycast fe80:: dev wpan0  metric 0 
anycast fe80:: dev wlan0  metric 0 
ff00::/8 dev br-lan  metric 256 
ff00::/8 dev eth0  metric 256 
ff00::/8 dev wpan0  metric 256 
ff00::/8 dev wlan0  metric 256 
root@KNBA5F000300:~# 
root@KNBA5F000300:~# ifconfig 
br-lan    Link encap:Ethernet  HWaddr 00:A0:03:97:08:FE  
          inet addr:192.168.8.1  Bcast:192.168.8.255  Mask:255.255.255.0
          inet6 addr: fd8d:7059:cff4::1/60 Scope:Global
          inet6 addr: fe80::2a0:3ff:fe97:8fe/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:361 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:76316 (74.5 KiB)

eth0      Link encap:Ethernet  HWaddr 00:A0:03:97:08:FD  
          inet addr:192.168.222.87  Bcast:192.168.222.255  Mask:255.255.255.0
          inet6 addr: fe80::2a0:3ff:fe97:8fd/64 Scope:Link
          inet6 addr: fdef:ae77:a044:3043:2a0:3ff:fe97:8fd/64 Scope:Global
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:7589 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4378 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:912283 (890.9 KiB)  TX bytes:11855243 (11.3 MiB)

eth1      Link encap:Ethernet  HWaddr 00:A0:03:97:08:FE  
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:367 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:77821 (75.9 KiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:896 errors:0 dropped:0 overruns:0 frame:0
          TX packets:896 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:143747 (140.3 KiB)  TX bytes:143747 (140.3 KiB)

wlan0     Link encap:Ethernet  HWaddr 00:A0:03:97:08:FF  
          inet6 addr: fe80::2a0:3ff:fe97:8ff/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:104 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:21986 (21.4 KiB)

wpan0     Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet6 addr: fe80::f404:79b4:ec0e:730f/64 Scope:Link
          inet6 addr: fd31:8f54:8c96:326d:0:ff:fe00:fc11/64 Scope:Global
          inet6 addr: fda6:54a6:89f3:1:f96e:31f7:eb3d:955d/64 Scope:Global
          inet6 addr: fd31:8f54:8c96:326d:0:ff:fe00:b000/64 Scope:Global
          inet6 addr: fd31:8f54:8c96:326d:0:ff:fe00:fc00/64 Scope:Global
          inet6 addr: fd31:8f54:8c96:326d:8c9b:f13:bdbf:f26/64 Scope:Global
          inet6 addr: fd31:8f54:8c96:326d:0:ff:fe00:fc34/64 Scope:Global
          inet6 addr: fd31:8f54:8c96:326d:0:ff:fe00:fc10/64 Scope:Global
          inet6 addr: fd31:8f54:8c96:326d:0:ff:fe00:fc38/64 Scope:Global
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1280  Metric:1
          RX packets:33 errors:0 dropped:0 overruns:0 frame:0
          TX packets:59 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:2930 (2.8 KiB)  TX bytes:6477 (6.3 KiB)

root@KNBA5F000300:~# 
root@KNBA5F000300:~# ping fd31:8f54:8c96:326d:3b99:56a4:46f0:4e3c
PING fd31:8f54:8c96:326d:3b99:56a4:46f0:4e3c (fd31:8f54:8c96:326d:3b99:56a4:46f0:4e3c): 56 data bytes
64 bytes from fd31:8f54:8c96:326d:3b99:56a4:46f0:4e3c: seq=0 ttl=255 time=32.024 ms
64 bytes from fd31:8f54:8c96:326d:3b99:56a4:46f0:4e3c: seq=1 ttl=255 time=32.710 ms
64 bytes from fd31:8f54:8c96:326d:3b99:56a4:46f0:4e3c: seq=2 ttl=255 time=34.415 ms

--- fd31:8f54:8c96:326d:3b99:56a4:46f0:4e3c ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 32.024/33.049/34.415 ms
root@KNBA5F000300:~# 
root@KNBA5F000300:~# coap-client -m get coap://[fd31:8f54:8c96:326d:3b99:56a4:46f0:4e3c]/dev/fwv
root@KNBA5F000300:~# 
root@KNBA5F000300:~# 
root@KNBA5F000300:~# coap-client -m get coap://[fd31:8f54:8c96:326d:3b99:56a4:46f0:4e3c]/dev/fwv

[jwhui]

For communication within a given Thread mesh, the ML-EID should be sufficient.

It could be that the CoAP response is getting filtered within PassToHost:

openthread/src/core/net/ip6.cpp

Line 927 in 4545daf

Error Ip6::PassToHost(OwnedPtr<Message> &aMessagePtr,

Can you provide logs and packet capture for more visibility?