Read the routes in your first RPL DODAG

Steps

Screens captured against Contiki-NG Cooja Contiki-NG release/v4.9 c20b12cd, Cooja 4.8 (2022071901), Temurin 17.0.20.1, image sha256:b14d5afb0a2a852d9e72bbed607ead03f6ccc5f4d4dee44f0799110be2f4b609 on 2026-09-10; the tool may have moved on — the text steps are the contract.

1. 1 Step 1

   Do

   Open the prepared CSC and let it stop at 90 seconds. Trace mote 4’s arrows toward root 1 in Network.

   You will see

   The parent chain is 4 → 2 → 1; motes 5 and 6 use parent 3.

   Why it matters

   A preferred-parent graph is the starting hypothesis for forwarding; the packet tests below check it.

2. 2 Step 2

   Do

   In Mote output, filter for ^-- (fd00|fe80)::204. Read the two addresses printed by ip-addr at 60.065 s.

   You will see

   Mote 4 has fd00::204:4:4:4 and fe80::204:4:4:4.

   Why it matters

   The shared fd00::/64 prefix and the link-local address serve different scopes. Neither address alone proves reachability.

3. 3 Step 3

   Do

   Filter for ^-- fe80::202.*lifetime|^-- Preferred parent|^-- Rank:. Match the default route to the parent arrow, then complete the README’s prefix worksheet.

   You will see

   Mote 4’s default route and preferred parent are fe80::202:2:2:2; its observed Rank is 467. The worksheet chooses /24, /16, /8, then /0.

   Why it matters

   A dynamic RPL default next hop and a longest-prefix lookup answer different questions. Prefix length wins before metric in the worksheet.

4. 4 Step 4

   Do

   Filter for Received ping reply from fe80. Check the scheduled ping to mote 4’s selected next hop.

   You will see

   Mote 4 receives a reply from fe80::202:2:2:2: len 4, ttl 64, delay 31 ms.

   Why it matters

   A selected route needs a reachable next hop. This one-hop test is checked before the root test.

5. 5 Step 5

   Do

   Filter for Received ping reply from fd00|^Timeout$. Compare the root ping at 70 s with the absent-destination ping at 76 s.

   You will see

   The root reply has ttl 63 and delay 198 ms; the nonexistent fd00::299:99:99:99 destination times out at 81.065 s.

   Why it matters

   A working default next hop does not guarantee every destination or return path. The one-hop/two-hop TTL comparison is measured; the README traceroute worksheet is a separate model.

6. 6 Step 6

   Do

   Filter for Received request 'hello 7'|Received response 'hello 7'. Match each request’s mote address and payload with the returning response. Finish the README routing record.

   You will see

   The displayed hello 7 exchanges include actual root receptions and client replies. The full log totals 31 requests received from all five clients, with replies reaching all five.

   Why it matters

   Application replies add evidence beyond a route table or ICMP probe. State that Internet forwarding and production RF reliability remain untested.