I read in one of Job descritpion "Experience of working on circuit(T1/E1,T3/E3,Ethernet) troubleshooting would be preferred".
Could u please help me this "circuit t1/e1,etc". Is it covered in ccna or ccnp rs ?
Is it frame-relay or mpls or other?
Could you please explain or suggest me the book/blog/doc/etc.
