# How long is the update routing table time? Or update mechanism? **URL:** \ **Category:** XBee & XBee Gateway\ **Tags:** table, time, routing, update\ **Created:** [December 27, 2016, 10:43am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830 "2016-12-27T10:43:44Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![hwjang11](https://avatars.discourse-cdn.com/v4/letter/h/41988e/32.png) [@hwjang11](https://forums.digi.com/u/hwjang11)\ **Post date:** [December 27, 2016, 10:43am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/1 "2016-12-27T10:43:44Z")
I have this configuration as below. C-R1-E. I added new router R2 between C and R1. Actually R2 is near R1. So I thought R1’s routing table would show the route path R1-R2-C. But it didn’t show it when I read the route table of R1 by ZDO command.The route table wasn’t updated… I don’t know the routing table update period or the update mechanism for routing table… Let me know how to get the latest route table in the xbee module. ---
**Author:** ![mvut](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/mvut/32/31_2.png) [@mvut](https://forums.digi.com/u/mvut)\ **Post date:** [December 27, 2016, 10:51am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/2 "2016-12-27T10:51:55Z")
A routing table is only updated if the current rout is broken. And No, it would not be C - R1 - R2 -E unless the Router 1 was only in range of the Coordinator, router 2 was only in range of both the end device and router 1. ---
**Author:** ![hwjang11](https://avatars.discourse-cdn.com/v4/letter/h/41988e/32.png) [@hwjang11](https://forums.digi.com/u/hwjang11)\ **Post date:** [December 28, 2016, 11:25am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/3 "2016-12-28T11:25:58Z")
Thanks for your reply… But I said that I added R2 between C and R1. So, I thought that your routing table would add also new path R1-R2-C, besides old path(R1-C). But it didn’t that… If your policy is that a routing table is only updated if the current route is broken, it is correct. But your X-CTU shows new path… ---
**Author:** ![mvut](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/mvut/32/31_2.png) [@mvut](https://forums.digi.com/u/mvut)\ **Post date:** [December 28, 2016, 1:36pm UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/4 "2016-12-28T13:36:40Z")
It really does not matter where you placed R2. The point being that as long as your R1 and the Coordinator and End device are in range, it will never send data via R2. The reason for that is that it is always going to take the least amount of hops to get the data from Point A to point Z. ---
**Author:** ![hwjang11](https://avatars.discourse-cdn.com/v4/letter/h/41988e/32.png) [@hwjang11](https://forums.digi.com/u/hwjang11)\ **Post date:** [December 29, 2016, 10:13am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/5 "2016-12-29T10:13:16Z")
E’s parent is R1…But R1 has new path to C. You mean that R1’s routing table isn’t updated unless R1 is disassociated. The LQI among R1-R2-C maybe better than the LQI between R1 and C. But you mean that it doesn’t matter in your routing policy… ---
**Author:** ![mvut](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/mvut/32/31_2.png) [@mvut](https://forums.digi.com/u/mvut)\ **Post date:** [December 29, 2016, 10:29am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/6 "2016-12-29T10:29:23Z")
No that is not what I am saying. As long as the router 1 is in range of the the coordinator, it is going to send the data direct. That is, it is not going to use another router to forward the data to the coordinator. No when it can get it to the coordinator all on its own. ---
**Author:** ![hwjang11](https://avatars.discourse-cdn.com/v4/letter/h/41988e/32.png) [@hwjang11](https://forums.digi.com/u/hwjang11)\ **Post date:** [January 5, 2017, 10:53am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/7 "2017-01-05T10:53:29Z")
1. If then, there is no way that routing table of a router is updated periodically? 2. Why X-CTU can show new path? ---
**Author:** ![mvut](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/mvut/32/31_2.png) [@mvut](https://forums.digi.com/u/mvut)\ **Post date:** [January 5, 2017, 11:13am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/8 "2017-01-05T11:13:16Z")
The routing tables are updated automatically if the existing table is incorrect. XCTU is doing a neighbor table lookup. That is how it determines the paths that are available. ---
**Author:** ![hwjang11](https://avatars.discourse-cdn.com/v4/letter/h/41988e/32.png) [@hwjang11](https://forums.digi.com/u/hwjang11)\ **Post date:** [January 9, 2017, 8:25am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/9 "2017-01-09T08:25:09Z")
What do you mean that the existing table is incorrect? 1. If I added R2 between C and R1, neighbor information of R1 is updated. But the routing table of R1 is not updated unless the R1 is disconnected. 1. Can R1 do neighbor table lookup? if then, how? ---
**Author:** ![mvut](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/mvut/32/31_2.png) [@mvut](https://forums.digi.com/u/mvut)\ **Post date:** [January 9, 2017, 10:31am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/10 "2017-01-09T10:31:12Z")
Yes you just need to issue a ZDO command to read the neighbor table. ---
**Author:** ![hwjang11](https://avatars.discourse-cdn.com/v4/letter/h/41988e/32.png) [@hwjang11](https://forums.digi.com/u/hwjang11)\ **Post date:** [January 10, 2017, 10:15am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/11 "2017-01-10T10:15:41Z")
1. You mean that X-CTU shows new the map by using neighbor tables not routing tables? But it shows LQI information between the path… 2. Actually I think that the neighbor table’s LQI by using ZDO (0x8031) seems not proper. ---
**Author:** ![mvut](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/mvut/32/31_2.png) [@mvut](https://forums.digi.com/u/mvut)\ **Post date:** [January 10, 2017, 10:23am UTC](https://forums.digi.com/t/how-long-is-the-update-routing-table-time-or-update-mechanism/17830/12 "2017-01-10T10:23:13Z")
XCTU uses different options for different radios. For the Zigbee enabled devices, I believe it uses the neighbor table. As for LQI, there are ways to test that and obtain it.