In an MPLS (Multiprotocol Label Switching) data frame, the MPLS label resides between the Layer 2 (MAC) and Layer 3 (IP) headers.
The official routing protocol used for distributing labels in MPLS (Multiprotocol Label Switching) networks is not LDP (Label Distribution Protocol) but rather BGP (Border Gateway Protocol) in combination with the extensions for MPLS known as BGP-MPLS.
In the context of MPLS (Multiprotocol Label Switching), the router responsible for adding labels to routes discovered by BGP (Border Gateway Protocol) is not referred to as an LSR (Label Switching Router), but rather as an LER (Label Edge Router).
LER stands for Label Edge Router, and it operates at the edge of an MPLS network. When an IP packet enters the MPLS network from a non-MPLS domain, the LER is responsible for assigning a label to the packet based on the destination IP address. It uses the BGP (Border Gateway Protocol) or other routing protocols to learn the IP routes and then adds the appropriate MPLS label to the packets before forwarding them into the MPLS network.
The hardware component that inserts or removes labels from frames as they enter or leave the provider's MPLS network is called the "Edge Label Switch Router" (Edge LSR or E-LSR).
CEF (Cisco Express Forwarding) creates the Forwarding Information Base (FIB) table. The FIB is a critical component of CEF and is used to make forwarding decisions in Cisco routers and switches. It is a table that contains information about the next-hop addresses or interfaces to which packets should be forwarded based on their destination IP addresses.
The Data plane (also known as the Forwarding plane or Data Forwarding plane) in MPLS handles label swapping and transfers data based on Layer 3 (L3) or Layer 2 (L2) information.
An MPLS label consists of 32 bits. It is a 32-bit field that is used to identify and route packets within an MPLS network. The label contains various fields, including the label value itself, Experimental (EXP) bits, Time-to-Live (TTL) value, and a bottom-of-stack (BoS) indicator if multiple labels are present in the MPLS label stack.
In MPLS (Multiprotocol Label Switching), the plane that contains label 3 routing and label exchange protocols is the "Control plane."
MPLS (Multiprotocol Label Switching) is not based on a Cisco-exclusive technology. MPLS is a widely adopted and standardized technology used to enhance the performance and efficiency of packet switching networks. It was initially proposed by the Internet Engineering Task Force (IETF) in the late 1990s and has become a fundamental part of modern networking.
