MPLS Network Basics Quiz

Study Notes

MPLS Overview

MPLS (Multiprotocol Label Switching) allows for efficient data forwarding in networks by using labels instead of long IP addresses.
In an MPLS network, routers classify incoming packets into Forwarding Equivalence Classes (FECs), which are then mapped to Label-Switched Paths (LSPs).

Router Types

Label Edge Router (LER): Acts as an entry/exit point for MPLS packets, applying or removing labels.
Label Switching Router (LSR): Any router capable of switching MPLS packets, processing packets based solely on their labels.
Ingress LSR: Pushes a label onto incoming packets (PUSH/Impose operation).
Intermediate LSR: Swaps the label on packets (SWAP operation) before forwarding.
Egress LSR: Removes labels from packets (POP operation) before sending them out of the MPLS domain.

LSP and Traffic Handling

A Label Switched Path (LSP) is a predefined path for packets through an MPLS network based on labels.
At each router (LSR), packets are received with incoming labels, processed, and forwarded with appropriate outgoing labels.
Signaling protocols like RSVP-TE configure LSPs by utilizing network link information to optimize traffic routing.

MPLS Operational Mechanics

MPLS-capable routers utilize separate forwarding tables for labels, distinct from IP forwarding tables, allowing for flexible traffic management.
MPLS supports traffic engineering, enabling specific routes to be assigned or altered based on network conditions.
Pre-computed backup paths are essential for maintaining service continuity, particularly for time-sensitive applications like VoIP.

Traffic Engineering Benefits

MPLS can adaptively route traffic to alleviate congestion, meaning operations can explicitly select paths to avoid network overload.
For example, traffic from router A to D might use a less congested path through A-B-C-D rather than the direct connection that becomes overloaded.

MPLS Tables and Commands

In a router, the MPLS forwarding table contains entries that map incoming labels to corresponding outgoing labels and interfaces.
Commands like show mpls ip binding and show mpls forwarding-table help network administrators observe label bindings and current forwarding paths in the MPLS setup.

Applications of MPLS

Used for traffic engineering, enabling explicit control of traffic paths, which traditional IP routing protocols fail to achieve effectively.
Ideal for environments where maintaining low latency, high throughput, and efficient use of bandwidth is critical, particularly in enterprise and service provider networks.

Description

Test your knowledge on MPLS (Multiprotocol Label Switching) network basics such as label assignment, LSPs, FECs, LERs, and LSRs. Understand the concepts of IP packets division and MPLS routers' roles.