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Thread - LastCommTime and Timestamp

Question asked by RYAN BRYNGELSON on Oct 31, 2016
Latest reply on Nov 8, 2016 by Anthony Huereca

In the THCI response to a GetNeighborInfo request, what time base does the field LastCommTime have?  For instance, when I power cycle a device and begin reading neighbor info, some neighbors come back with a LastCommTime of greater than 4200.


I see in thci.c LastCommTime is defined as...


lastCommTime = ((uint32_t)TmrMicrosecondsToSeconds(TMR_GetTimestamp()) - pThrNeighbor->timestamp);


Is pThrNeighbor->timestamp restored from non-volatile memory?  I'm trying to figure out LastCommTime for a neighbor comes back as a large number when the device has only been powered up for less than 60 seconds.


How does the field Timeout relate to LastCommTime?  Let's consider a REED device, will a neighbor ever drop off the list?  For instance, let say we have tree devices, X, Y, and Z.  All three are REEDs (they all are routers) and X is the leader.  X can directly communicate with Y, Y can directly communicate to Z, and X can communicate to Z via Y.


X  -->  Y  -->  Z


In my experience, X shows Z as a neighbor even though it can't directly communicate to it.  The reading the neighbor info out of X, Z's LastCommTime continues to grow and the Timeout is 0.


Any help in understanding the LastCommTime and Timeout fields with respect to neighbors would be appreciated.