title: LLDP chassis ID origin
body: <p>I am learning about LLDP protocol and have stumbled across terms <code>chassis ID</code> and <code>port ID</code>. If I understand correctly they can be used by network management systems to determine connections between various devices in the network.</p>
  
  <p><strong>Question</strong>: 
  Where does the system get its <code>chassis ID</code> from? </p>
  
  <p>AFAIK there is no way to get a per-device unique identifier (for every possible device model). Also, on an Extreme switch I queried for SNMP OID <code>1.0.8802.1.1.2.1.3.2</code> (LLDP_LOC_CHASSIS_ID) I got back 6 bytes which seems a bit short for a worldwide device identifier. Am I missing something? Is chassis ID just some random number and implementators figured that the likelihood of collision was too low to worry about?</p>
  
  <p><strong>Bonus question 1</strong>:
  At what point is LLDP <code>chassis ID</code> initialized? My guess is that it shouldn't change even if LLDP is disabled and then re-enabled. If this is so, is it possible to get it somehow even if LLDP is disabled?</p>
  
  <p><strong>Bonus question 2</strong>:
  Does LLDP <code>chassis ID</code> change if you use another LLDP daemon?</p>