Which list defines the contents of an MPLS label?

Which list defines the contents of an MPLS label?
A . 20-bit label; 3-bit traffic class; 1-bit bottom stack; 8-bit TT
C . 32-bit label; 3-bit flow label; 1-bit bottom stack; 8-bit hop limit.
D . 20-bit label; 3-bit flow label: 1-bit bottom stack; 8-bit hop limit
E . 32-bit label; 3-bit traffic class; 1-bit bottom stack; 8-bit TTL

View Answer

Answer: A

Explanation:

MPLS uses a 32-bit label field that contains the information that follows:

+ 20-bit label (a number)

+ 3-bit class of service (or experimental field, typically used to carry IP precedence value)

+ 1-bit bottom-of-stack indicator (indicates whether this is the last label before the IP header)

+ 8-bit TTL (equal to the TTL in the IP header)