Why compare partition id when selecting parents ?

[jinwon0325kim]

Hi All,

Looking at the code, check Partition Id when selecting parents.
However, Partition Id is created randomly and I don't understand how to use it to select parents.

The HandleParentResponse function performs the ComparePartitions fuction that compares the newly received parent information
with the previously stored parent information.

if (aLeaderDataA.GetPartitionId() != aLeaderDataB.GetPartitionId())
{
    ExitNow(rval = aLeaderDataA.GetPartitionId() > aLeaderDataB.GetPartitionId() ? 1 : -1);
}

[jwhui]

Thread specifies how Thread devices merge partitions. Partitions with larger Partition ID values take precedence. The code you referenced implements the specified behavior. Merging partitions helps ensure that devices can communicate with each other when radio connectivity exists. See Thread 1.1.1 Section 5.16.3 for more details.