The IS-IS neighbor timeout interval is inconsistent.

AR1 is directly connected to AR2 and establishes IS-IS neighbor relationships with each other.

I found that the IS-IS peer holdtime of AR1 is 15s, which is 5s of AR2. Why is this, a network newcomer is seeking help.

<AR1>dis isis peer

                          Peer information for ISIS(1)

  System Id     Interface          Circuit Id       State HoldTime Type     PRI

-------------------------------------------------------------------------------

0000.0000.0002  GE1/0/0            0000.0000.0001.01 Up   5s      L2       64  

Total Peer(s): 1

<AR2>dis isis peer

                         Peer information for ISIS(1)

  System Id     Interface          Circuit Id       State HoldTime Type     PRI

-------------------------------------------------------------------------------

0000.0000.0001  GE1/0/0            0000.0000.0001.01 Up   15s       L2       64

Total Peer(s): 1

The IS-IS hello interval configured on the two router port is 5s.

interface GigabitEthernet1/0/0 
  IS-IS timer hello 5 level-2