How Supervisor Engines Power Network Performance

Every time you send an email, stream a video or access a website, your network switch or router relies on a powerful component called the network supervisor to guide the data packets to their destination. Network downtime can cost businesses an average of $5,600 per minute, according to Gartner. Supervisor engines play a vital role in preventing these costly outages, acting as the guardians of your network's health.

Imagine a bustling office with hundreds of employees simultaneously accessing cloud applications, streaming videos, and collaborating on projects. A network supervisor orchestrates this complex traffic flow, ensuring smooth operation and optimal performance.

A network supervisor is the central brain of a modular network device, like a switch or router. It oversees the control and data planes, ensuring efficient routing and forwarding of network traffic. Understanding how network supervisors work is not just beneficial. It's crucial for optimizing network performance, troubleshooting issues, and implementing advanced networking features. But what exactly is a network supervisor, and how does it accomplish these critical tasks?

In today's interconnected world, networks are the backbone of businesses and organizations. Network supervisors, control and data planes have a rich history that has shaped the way we understand and optimize network performance. They play a critical role in ensuring these networks operate smoothly and efficiently. In this article, we'll explore the key functions of network supervisors, delve into the intricacies of control and data planes, and examine how these components work together to optimize network performance.

Control Plane vs. Data Plane: Understanding the Differences

The control and data planes are two fundamental components of networking devices that work together to enable the routing and forwarding of data packets within a network. While they both contribute to the overall operation of a network device, they serve distinct functions and operate at different layers of the networking architecture. Let's delve into the key differences between the control plane and the data plane:

1. Control plane:

Often referred to as the brain of the network, the control plane is the mastermind behind determining the most efficient path for data packets to traverse a network. It achieves this through network structure discovery, route calculation, network health monitoring, and device signaling. Now, let's delve into the fascinating features of the control plane:

· Routing Protocols: The control plane processes routing protocols such as OSPF, BGP, and RIP to exchange information and build a routing table.

· Topology Discovery: Control plane mechanisms discover the network topology by exchanging routing updates and maintaining a map of network links and devices. Topology discovery depends on which routing protocol is used, such as the distance vector or link state routing protocol. Another example is the CDP or LLDP protocols.

· Route Calculation: The control plane calculates the optimal paths (best path) for data packets to reach their destinations based on the information gathered from routing protocols and network topology. Best path calculation also depends on which routing protocol is used. For example, link state protocols use the Dijkstra Algorithm, whereas Distance vector protocols use the Bellman-Ford for route calculation.

· Configuration and Management: The control plane also handles device configuration, management tasks, and policy enforcement, ensuring the network operates according to predefined rules and policies. For example, SNMP or NetFlow can monitor and configure the network hardware; network automation is a fascinating topic today.

2. Data Plane:

The data plane, also known as the forwarding plane or forwarding engine, is responsible for the actual forwarding of data packets based on the information provided by the control plane. It operates lower than the control plane and focuses on packet switching and forwarding. Critical aspects of the data plane include:

Packet Forwarding: The Data plane processes incoming data packets and forwards them to the appropriate outgoing interface based on the forwarding table or information base (FIB).

Fast Packet Processing: Network traffic is growing exponentially. Today, standard network interfaces operate at speeds of 40Gb or 100Gb.

The Data plane is being optimized for high-speed packet processing, with dedicated hardware components such as ASICs (Application-Specific Integrated Circuits) or network processors(NPU) to ensure efficient packet switching and forwarding.

Access Control: The Data plane enforces access control policies by filtering packets based on predefined rules, such as access control lists (ACLs), to allow or deny packet transmission.

Quality of Service (QoS): The Data plane implements QoS policies to prioritize certain types of traffic over others, ensuring that critical applications such as Voice or Video receive the necessary bandwidth and latency requirements.

Key Differences:

Function: The control plane determines the path packets should take through the network, while the data plane forwards the packets along those paths. In a nutshell, the control plane defines how the data plane forwards network traffic.

Location:  The control plane operates at a higher level of abstraction, dealing with routing protocols and network-wide decisions, while the data plane operates at a lower level, handling individual packets and their forwarding.

Processing: Control plane processing is typically done by the CPU and involves complex computations, whereas data plane processing is often offloaded to specialized hardware components, such as NPU or ASIC, for faster packet switching. If the data plane encounters an unknown destination address, it queries the control plane for the correct forwarding information.

In summary, the control and data planes ensure efficient network routing and forwarding of data packets. While the control plane focuses on high-level decision-making and route computation, the data plane focuses on the actual forwarding of packets based on the instructions received from the control plane.

For example, you use a GPS navigator in the car to find the best path to the destination and use the car as a vehicle to take you there. In this example, the GPS navigator acts as the control plane, and the car acts as the forwarding plane (data plane).

RIB and FIB

In computer networking, RIB and FIB stand for Routing Information Base and Forwarding Information Base, respectively.

1. Routing Information Base (RIB): This database is used by routers, switches, firewalls, or routing protocols to store routing information such as network topology, routing tables, and related information. It contains all possible routes the router knows about, including those learned from various routing protocols like OSPF, BGP, RIP, Static, and Directly connected routes. The RIB contains routes with their attributes and metrics and is where routing decisions are made. Keep in mind that the best path selection occurs through these steps:

·  Prefix length

·  Administrative distance

·  Metric

2. Forwarding Information Base (FIB): This is also known as the forwarding table. It's derived from the RIB and is used for actual packet-forwarding decisions. The FIB contains only the best paths to reach a destination network, chosen from the RIB based on routing protocols and administrative settings. When a packet arrives at a router, it checks the destination address against the entries in the FIB to determine where to forward the packet.

Right now, we know that the RIB is where all routing information is stored, while the FIB is a subset of the RIB containing only the most relevant information for forwarding packets. In a nutshell, the FIB contains the best information about the destination, which is obvious.

Route Engine vs. Forwarding Engine: Key Roles in Network Devices

The routing and forwarding engines are critical components of network devices such as routers. Still, they serve distinct functions related to the control and data planes.

§  The Routing engine, sometimes called the Control plane, manages the device's control plane functions.

§  The Forwarding engine, sometimes called the Data Plane, is responsible for actual packet forwarding based on the information provided by the Routing engine.

Why should we be familiar with Routes and forwarding engines? The following describes two concepts about forwarding packets.

Centralized vs. Distributed Forwarding

Distributed and centralized forwarding are two different approaches to managing network traffic within a network infrastructure, particularly in the context of switches and routers. Let's break down each:

1. Centralized Forwarding:

All packet forwarding decisions are made by a central entity, CPU, or a centralized controller in centralized forwarding. When a packet arrives at a switch or router, it is forwarded to the central entity for processing and decision-making.

Decision-making, in this context, refers to the process of de-encapsulating packets and extracting relevant information to determine the appropriate forwarding path. The central entity then determines the appropriate output port for the packet based on various factors, such as routing tables, ACLs, and QoS policies.

Then, forward the packet out of the proper port. Examples of centralized forwarding architectures include traditional router architectures, where the router's CPU makes all routing decisions.

2. Distributed Forwarding:

 In distributed forwarding, forwarding decisions are made locally by individual line cards, interface modules, or forwarding engines within the switch or router. Each forwarding entity within the device has its forwarding tables and algorithms to determine the best output port for incoming packets. When a packet arrives at the line card, the forwarding entity de-encapsulates the packet and makes the forwarding decision independently, without involving a central controller or CPU.

Distributed forwarding can offer advantages in terms of scalability and performance as it distributes the forwarding workload across multiple entities within the network device. Many modern high-performance switches and routers utilize distributed forwarding architectures to handle large traffic volumes efficiently.

The above diagram illustrates that each line card operates with its own independent control and data plane.

What are Supervisor Engines

In the realm of network hardware, particularly in the context of modular network devices like switches and routers, supervisor engines hold a pivotal role in ensuring the reliable operation and management of the device. Analogous to a computer's motherboard, the supervisor engines serve as the central brain of the network device. Let's delve into an introduction to the supervisor:

1. Centralized Control and Management: Much like a computer's motherboard that orchestrates various components within a computer, the supervisor engines act as the central control unit of the network device. It manages and coordinates the device's operation, including configuration management, software upgrades, and system monitoring. Essentially, it serves as the brain of the network device, ensuring its reliability and efficiency.

2. Control plane Operation: The supervisor module typically hosts the control plane components within modular network devices, akin to a motherboard housing a computer's CPU and memory modules. These components include the routing engine, management processor, and control plane ASICs (Application-Specific Integrated Circuits). The supervisor oversees the execution of control plane processes, such as routing protocol operations, management functions, and network monitoring.

3. Hardware Interface: Similar to how a motherboard provides physical interfaces for connecting various peripherals and expansion cards, the supervisor module offers interfaces and connections for linking other modules or line cards within the network device. These interfaces facilitate communication between the supervisor and other components, enabling the exchange of data, control signals, and management information.

4. Redundancy and High Availability: The supervisor often incorporates redundancy schemes, failover mechanisms, and hot-swappable components to minimize downtime and maintain network continuity during component failures or system faults or implement features like a Virtual Switch System (VSS) or virtual Port Channel(vPC) in Cisco or Virtual chassis in Juniper.

5. Monitoring and Reporting: The supervisor module monitors the network device's health, performance, and operational status, similar to how a motherboard's monitoring systems oversee the health of components such as the CPU and memory you can see in BIOS. It collects data on various metrics, such as CPU utilization, memory usage, FAN tray Speed, and network traffic patterns. It generates reports or alerts informing administrators of anomalies, issues, or potential bottlenecks.

In summary, the supervisor module plays a critical role in modular network hardware, providing centralized control and management.

Evolution of Supervisor Engines and Their Role in SDN

Supervisor engines, once primarily responsible for managing hardware-centric control planes, have evolved significantly to embrace the paradigm shift brought about by Software-Defined Networking (SDN). Traditionally, supervisor engines served as the central control unit in modular network devices like switches and routers, ensuring efficient routing and forwarding of data packets. As network architectures grew more complex, these engines incorporated advanced processing capabilities and sophisticated management features to handle increasing demands.

Supervisor Engines in SDN

Software-defined networking (SDN) is a networking approach that centralizes network control and separates it from the underlying hardware. This shift has transformed the role of supervisor engines, requiring them to integrate with SDN controllers, which manage the network's control plane functions. In SDN-enabled environments, supervisor engines implement policies, manage traffic flows, and maintain network visibility, ensuring network security and performance.

Supervisor engines contribute to SDN's benefits by providing a critical interface between the physical network and the SDN controller, enabling dynamic policy enforcement, centralized monitoring, and more efficient network management.

Future Trends in Supervisor Engines' Technology

As networking technology continues to evolve, several emerging trends are shaping the future of supervisor engines. One key trend is the increased virtualization of these engines, offering greater flexibility and scalability, allowing deployment across various network environments, including cloud-based infrastructures, and enabling efficient resource utilization.

·  Increased Virtualization

·  Greater Programmability

·  Tighter Integration with Cloud-Based Management

·  Impact of AI and Machine Learning

Why we need Modular Network Hardware

A crucial feature for supervisor engines is redundancy, which can be achieved through technologies like Virtual Switching System (VSS).

In a VSS setup, two physical switches function as a single logical switch, with one designated as primary (active) and the other as secondary (standby). If the master switch fails for any reason, the secondary switch takes the master role without downing the whole of your network.

To implement VSS, you need two switches with the same supervisor and the same line cards module and connect the supervisors via fiber uplink.  Another example is vPC in the Nexus switch.