Exam 300-410 topic 1 question 300 discussion

MPLS headers do not include a sequence number of a checksum. Everything else are parts of the header.

A C D E are correct Label: This is a 20-bit field that identifies the MPLS label for the packet. It is used to determine how the packet should be forwarded. Experimental (Exp): This 3-bit field is used for experimental purposes and can be utilized for quality of service (QoS) or other features. It is often used to carry information such as priority or class of service. Bottom of Stack (BoS): This 1-bit field indicates whether the label is the last label in the stack. If set to 1, it means this is the bottom of the label stack. Time to Live (TTL): This 8-bit field is used to prevent looping of MPLS packets by decrementing its value at each hop. If the TTL value reaches zero, the packet is discarded.

yesy corerct Label value: the name says it all, this is where you will find the value of the label. EXP: these are the three experimental bits. These are used for QoS, normally the IP precedence value of the IP packet will be copied here. S: this is the “bottom of stack” bit. With MPLS it’s possible to add more than one label, you’ll see why in some of the MPLS VPN lessons. When this bit is set to one, it’s the last MPLS header. When it’s set to zero then there is one or more MPLS headers left. TTL: just like in the IP header, this is the time to live field. You can use this for traces in the MPLS network. Each hop decrements the TTL by one.