Exam 300-410 topic 1 question 90 discussion

The given answer is correct

C & D are correct

A. The label edge router swaps labels on the received packets. >> not true, edge routers add or remove labels B. Labels are imposed in packets after the Layer 3 header. >> not true, labels are imposed after L2 and before L3 C. LDP uses TCP for reliable delivery of information. >> OK D. An MPLS label is a short identifier that identifies a forwarding equivalence class. >> OK E. A maximum of two labels can be imposed on an MPLS packet. >> seems not true, "All IPv4 packets have one or more labels." - more info https://www.ciscopress.com/articles/article.asp?p=680824&seqNum=5

A. The label edge router swaps labels on the received packets. LSR swap label and LER take away the label or add the label when receive packet… but compare to other it seem this is more correct than other B. Labels are imposed in packets after the Layer 3 header. Label is layer 2.5 C. LDP uses TCP for reliable delivery of information. LDP is udp D. An MPLS label is a short identifier that identifies a forwarding equivalence class. Mpls label consists of the label and a fec for traffic engineering use. Not only fec E. A maximum of two labels can be imposed on an MPLS packet. One mpls label for lfib routing, one mpls vpn label for ibgp routing

LDP discover use UDP after flow use TCP. In this case decide TCP? I’m not sure.

the question here is about Label !!!! so i would say the right answer are B and D B because i think label came after the layer 3 header is added to the packet. C it is talking about LDP not label !!!???

voted for C and D

The given answer is correct C & D

A,D is true.