This is the sequence identifier that was associated with the SNMP Inform sent when this EAP session started. A management station uses this value to correlate a later EAP session end notification with the original session start event, linking the two into one session record. For example, an EAP session end notification carrying ubpNotifyEAPSessionStartSignalSequenceNumber value 4521 tells the receiver it closes out the session that began with the Inform bearing that same sequence number.