MPLS LABEL

MPLS uses a 32 bit header/label that contains the following information

20 Bit label :It’s a no. which is locally significant and assigned locally by router to FEC.

3 Bit experimental field : These three bits are known as experimental bits. This three bits is used for MPLS QOS purpose.

1 Bit bottom of stack indicator: The bit indicates which is last label in stack before IP header. Last label entry is 1 and others are 0.

8 Bit TTL field : This field has same function as IP header for Loop prevention in cloud.

MPLS label is inserted in between layer 2 and layer 3.

Watch in action -

MPLS operates at an OSI Model layer that is generally considered to lie between traditional definitions of Layer 2 (Data Link Layer) and Layer 3 (Network Layer), and thus is often referred to as a "Layer 2.5" protocol. It can be used to carry many different kinds of traffic, including IP packets, as well as native ATM, Frame relay and Ethernet frames.

*Note: Figures are from Cisco website