{"action":"created","issue":{"url":"https://api.github.com/repos/contiki-os/contiki/issues/1053","labels_url":"https://api.github.com/repos/contiki-os/contiki/issues/1053/labels{/name}","comments_url":"https://api.github.com/repos/contiki-os/contiki/issues/1053/comments","events_url":"https://api.github.com/repos/contiki-os/contiki/issues/1053/events","html_url":"https://github.com/contiki-os/contiki/pull/1053","id":74038162,"number":1053,"title":"RPL probing","user":{"login":"simonduq","id":1425999,"avatar_url":"https://avatars.githubusercontent.com/u/1425999?v=3","gravatar_id":"","url":"https://api.github.com/users/simonduq","html_url":"https://github.com/simonduq","followers_url":"https://api.github.com/users/simonduq/followers","following_url":"https://api.github.com/users/simonduq/following{/other_user}","gists_url":"https://api.github.com/users/simonduq/gists{/gist_id}","starred_url":"https://api.github.com/users/simonduq/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/simonduq/subscriptions","organizations_url":"https://api.github.com/users/simonduq/orgs","repos_url":"https://api.github.com/users/simonduq/repos","events_url":"https://api.github.com/users/simonduq/events{/privacy}","received_events_url":"https://api.github.com/users/simonduq/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/contiki-os/contiki/labels/RPL","name":"RPL","color":"d4c5f9"}],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":12,"created_at":"2015-05-07T16:02:59Z","updated_at":"2015-05-10T19:26:16Z","closed_at":"2015-05-10T15:22:10Z","pull_request":{"url":"https://api.github.com/repos/contiki-os/contiki/pulls/1053","html_url":"https://github.com/contiki-os/contiki/pull/1053","diff_url":"https://github.com/contiki-os/contiki/pull/1053.diff","patch_url":"https://github.com/contiki-os/contiki/pull/1053.patch"},"body":"This PR implements an optional probing mechanism for RPL. Nodes will periodically send a unicast message (DIO or DIS) to one of their best parents (mostly the current preferred and second best parent, sometimes also the third best), to keep link metric estimates up to date. The main benefit is that it avoids switching to a parent which is seemingly good but has an outdated link metric (or never updated, stuck at its initial value). \r\n\r\nWhen probing and refreshing our link estimate to the second best parent **S**, there are three possible consequences:\r\n(1) the link estimate remains roughly unchanged, **S** can be used safely as a backup in case the current preferred parent fails\r\n(2) the link proves better than we thought, RPL may chose to switch parent a now use **S**\r\n(3) the link proves worse than we thought, with its new link estimate **S** will no longer be the second best parent, we will be able to probe another parent until we find a safe backup to our current preferred parent\r\n\r\nThrough many deployments in different testbeds, with different platforms and MAC layers (Nullrdc, ContikiMAC, TSCH), we found that probing was a must when aiming for reliable RPL operation.\r\n"},"comment":{"url":"https://api.github.com/repos/contiki-os/contiki/issues/comments/100685198","html_url":"https://github.com/contiki-os/contiki/pull/1053#issuecomment-100685198","issue_url":"https://api.github.com/repos/contiki-os/contiki/issues/1053","id":100685198,"user":{"login":"adamdunkels","id":589970,"avatar_url":"https://avatars.githubusercontent.com/u/589970?v=3","gravatar_id":"","url":"https://api.github.com/users/adamdunkels","html_url":"https://github.com/adamdunkels","followers_url":"https://api.github.com/users/adamdunkels/followers","following_url":"https://api.github.com/users/adamdunkels/following{/other_user}","gists_url":"https://api.github.com/users/adamdunkels/gists{/gist_id}","starred_url":"https://api.github.com/users/adamdunkels/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/adamdunkels/subscriptions","organizations_url":"https://api.github.com/users/adamdunkels/orgs","repos_url":"https://api.github.com/users/adamdunkels/repos","events_url":"https://api.github.com/users/adamdunkels/events{/privacy}","received_events_url":"https://api.github.com/users/adamdunkels/received_events","type":"User","site_admin":false},"created_at":"2015-05-10T19:26:16Z","updated_at":"2015-05-10T19:26:16Z","body":"Nice to see the travis test in there!"}}