Route external networks using Thread.

[khrono252]

I have been doing a lot of tests using a Thread border router from ESP but can`t find a way to do this.

It seems that modifying the on mesh prefix to match the global address and setting manual routes gets a ICMP6 request to get inside the Thread network and be routed from BR1 to BR2.

I have some questions:
Can I have more than one on mesh prefix set on my network?
I should use a different kind of prefix?

For some reason when I add a manual route to the br1 after adding my prefix the prefix gets removed.

prefix add 2a0c:5a82:8100:6b00::/64 paosr low
route add 2a0c:5a82:8100:6b00::/64 med

Does someone know if this can be set on my network?

Any help will be appreciated.

[jwhui]

A Thread network can only be configured with one On-Mesh Prefix. However, a Thread network may be configured with multiple Off-Mesh Routable Prefixes.

In your diagram, it's not clear where the links are. For example, does the Linux box have one Ethernet connection to OT BR1 and a separate Ethernet connection to the Internet? Can you update your diagram to clearly show the separate Ethernet / Wi-Fi /Thread subnets?

[khrono252]

I tried the following configuration:

I assigned manually and address to linux 2 = 29be:8040:88dd:1000::1/60 Scope:Global
Added the following prefix on BR1 = 29be:8040:88dd:1000::/64 pars low 5000
Added the following route on BR1 = 29be:8040:88dd:1000:0:0::/96 s med 5000

So I tried to ping from Linux 1 to Linux 2 following this sequence:
Linux 1 -> BR1 -> BR2 -> Linux 2
But is not progressing to Linux 2, below are the logs:

BR1:
ip6_input: packet accepted on interface XX
ip6_input: packet not for us.
ip6_forward: forwarding packet to 29be:8040:88dd:1000:0:0:0:1

BR2:
I(5526106) OPENTHREAD:[I] MeshForwarder-: Received IPv6 ICMP6 msg, len:104, chksum:35d6, ecn:no, from:0xf400, sec:yes, prio:normal, rss:-51.0
I(5526106) OPENTHREAD:[I] MeshForwarder-: src:[fd15:3b73:2d91:c7a4:223:c1ff:fe27:0000]
I(5526106) OPENTHREAD:[I] MeshForwarder-: dst:[29be:8040:88dd:1000:0:0:0:1]
ip6_input: packet accepted on interface XX
ip6_input: packet not for us.
ip6_forward: not bouncing packets back on incoming interface.

BR1
netdata show
Prefixes:
fdaf:f825:c09a:1::/64 paos low 5000
29be:8040:88dd:1000::/64 pars low 5000
Routes:
fc00::/7 sa med 5000
fc00::/7 sa med f400
fdaf:f825:c09a:2:0:0::/96 sn low 5000
29be:8040:88dd:1000:0:0::/96 s med 5000
Services:
44970 5d fd7b1babf1be947a5c2038d64f91d69ad120 s 5000 1
44970 5d fd7b1babf1be947a09cbb4c13a86eacdd120 s f400 1
44970 01 5d000500000e10 s 5000 0
Contexts:
fdaf:f825:c09a:1::/64 1 c
29be:8040:88dd:1000::/64 3 c
Commissioning:
39488 - - -
Done

BR2
netdata show
Prefixes:
fdaf:f825:c09a:1::/64 paos low 5000
29be:8040:88dd:1000::/64 pars low 5000
Routes:
fc00::/7 sa med 5000
fc00::/7 sa med f400
fdaf:f825:c09a:2:0:0::/96 sn low 5000
29be:8040:88dd:1000:0:0::/96 s med 5000
Services:
44970 5d fd7b1babf1be947a5c2038d64f91d69ad120 s 5000 1
44970 5d fd7b1babf1be947a09cbb4c13a86eacdd120 s f400 1
44970 01 5d000500000e10 s 5000 0
Contexts:
fdaf:f825:c09a:1::/64 1 c
29be:8040:88dd:1000::/64 3 c
Commissioning:
39488 - - -
Done

I guess I have to manually setup ipv6 addresses to get different prefixes but still the ICMPv6 message is not reaching the destination it's like the border router didn't know where to send it.

[jwhui]

I think still lies from using the same /64 prefix on both the Thread network and Ethernet network:

I assigned manually and address to linux 2 = 29be:8040:88dd:1000::1/60 Scope:Global
Added the following prefix on BR1 = 29be:8040:88dd:1000::/64 pars low 5000

On BR2, Linux is trying to route the packet back to the Thread network, but drops it because the packet was received from the Thread network.

ip6_input: packet accepted on interface XX
ip6_input: packet not for us.
ip6_forward: not bouncing packets back on incoming interface.

[khrono252]

Hi Jonathan, I'm getting confused here. When you said it is the same prefix you mean that even if the IP address is /60 is still the same prefix as /64? From my tests I understand that to be able to route something via the thread mesh I need to publish that prefix as off-mesh otherwise it doesn´t get routed and is just rejected on the entry BR. Also, SLAAC only works with /64 prefixes. What would be the appropriate configuration for the prefix and prefixs flags in this scenario? How can I route a packet that comes from an external network without adding a similar prefix as off-mesh?

Just adding the routes manually doesn´t seem to do the trick. Appreciate the help so far, I'll keep doing more testing.

[jwhui]

In your example above, the IPv6 Destination Address is 29be:8040:88dd:1000:0:0:0:1. With longest prefix matching, the packet will be routed back into the Thread network, since 29be:8040:88dd:1000::/64 is assigned to the Thread network.

If you are trying to reach an end point outside the Thread network, the IPv6 Destination Address should be set to something that does not match the Thread network prefix.

[khrono252]

I was able to fix this, so I'm closing this conversation. Thanks for your support. @jwhui