Capgemini Engineering Network Engineer interview questions

i applied online and got call from aricent for interview then interview was done first round was basic intro and comm skills nothing tough but the second round was very tough the person asked about osi model in so detail i was thinking all the time answering it then he started with protcols switchng stp most famous was to know everyting about it as i already knew it thought it will be easy but that was tough as well then routing protocols again deep ospf and eigrp and all was extremely tough again got call from them i had cleared the round discussed salary i got what i wanted but then i thought i had asked too low they could offer me much better