Ques. do fiber link have any circuit Id to lodge the complain when link have any problem
Ans. Yes every link including fiber link has an circuit Id to uniquely identify it.
When an ISP ( Internet service provider) gives a leased line connection. it provides a Circuit Id to the customer but this is in case of enterprises, in case for home users where simultaneously many users have to share single link are provided with a unique customer Id.
When facing problem customer can lodge a complaint with their ISP using this unique customer Id( in case of home users) or Circuit Id( in case of enterprise users).