This blog will discuss Hierarchical Network Architecture. You will understand the Cisco hierarchical model’s three tiers and how they are employed in network architecture. Network design begins with an analysis of the network component; it is beneficial to classify networks based on the number of devices served:
- A small network supports up to 200 devices.
- A medium network supports between 200 and 1000 devices.
- The extensive network supports over 1000 devices.
Network architectures differ according to an organisation’s size and requirements. An extensive company network typically comprises a central campus connecting small, medium, and significant locations. This section will discuss generally established network architecture ideas.
STRUCTURED ENGINEERING PRINCIPLES
Regardless of the network’s size or requirements, a critical aspect in ensuring the correct execution of any network design is adhering to sound structured engineering principles:
A hierarchical network model is an effective high-level tool for creating a dependable network architecture. Divide the complicated task of network architecture into smaller, more manageable chunks.
- Modularity: By isolating the numerous functions found in a network into modules. Cisco classified the corporate campus, the service block, the data centre, and the Internet perimeter as modules.
- Resistance: The network must be accessible to be utilised in normal and abnormal situations (maintenance periods) (hardware or software failures).
- Flexibility: The ability to change network portions, introduce new services, or expand capacity without requiring substantial changes (i.e., replace major hardware devices).
The network must be structured on a hierarchical architecture that allows for expansion and adaptability to accomplish these core design objectives.
Cisco Hierarchical Model
A hierarchical architecture in network technology entails segmenting the network into distinct levels. Each layer in the hierarchy performs unique functions that determine its role in the more extensive network. This enables the network designer and architect to optimise and choose the required network features, hardware, and software. Hierarchical models are used in the design of LANs and WANs.
A typical hierarchical LAN network architecture for a corporate campus contains the following three layers:
- The access layer enables workgroups and individual users to connect to the network.
- The distribution layer establishes a connection on a policy-based basis and manages the border between the access and core layers.
- The core layer enables rapid communication between distribution switches across the company campus.
The advantage of segmenting a flat network into smaller, more manageable portions is that local traffic stays local, and only traffic to other networks is routed through a higher layer. In a flat network, layer two devices offer minimal chances to manage broadcasts or filter undesired traffic. Response times worsen when additional devices and applications are added to a flat network until the network becomes unworkable.
ACCESS LAYER:
In a Local Area Network context, the access layer allows terminals access to the network. You may give remote workers or remote locations access to the company network in a WAN environment through WAN connections.
The access layer is responsible for a variety of tasks, including the following:
- Switching at the Layer 2
- High accessibility
- Port Security
- Classification and labelling of QoS
- Address Resolution Protocol inspection
- Virtual Access Control Lists
- Expansion tree
- Auxiliary Ethernet and Virtual LAN power for VoIP
DISTRIBUTION LAYER:
Before data is delivered to the core layer for routing to its destination, the distribution layer gathers it from the access layer switches. In wire cabinets, the distribution layer is the focal point. A multilayer router or switch is utilised to split workgroups and isolate network issues. A distribution layer switch can serve numerous access layer switches.
The distribution layer may have the following capabilities:
- Aggregation of LAN or WAN links.
- Access control lists (ACLs) and provide policy-based security filtering.
- Routing services between local area networks (LANs) and virtual local area networks (VLANs), as well as between routing domains.
- Availability and load balancing.
- The core layer’s interfaces specify a limit on route aggregation and summarization.
- Control over the broadcast domain, as neither routers nor multilayer switches, rebroadcast broadcasts. The gadget acts as a boundary between broadcast zones.
CORE LAYER:
The core layer is frequently referred to as the “backbone of the network.” Some network equipment, such as Cisco Catalyst (6500) or (6800) series switches, comprise the core layer. These are intended to quickly switch packets and link various campus components, including distribution modules, service modules, data centres, and the WAN boundary.
The core layer is critical for interconnectivity between the distribution layer devices; it links the distribution block to the WAN and Internet perimeters. The central processing unit (CPU) must be highly available and redundant. Because the kernel collects traffic from all distribution layer devices, it must be capable of quickly sending enormous volumes of data.
Several factors to consider when it comes to the core layer include the following:
- You must ensure that high-speed switching is available (i.e., fast transport).
- It must be dependable and fault-tolerant.
- The core ability must achieve scalability through speedier teams, not by adding more units.
- It would be best to avoid packet handling that places a heavy load on the CPU due to security, inspection, categorisation of quality of service (QoS), or other activities.
Why is it critical to create hierarchical networks?
Hierarchical networks have several advantages, including increased performance, stability, scalability, greater security, simplified management and design, and cost-effectiveness. Let’s take a closer look at each of them below.
1. Performance enhancements:
A hierarchical network architecture implies that data is routed near wire speed through aggregated switchport lines rather than through lower-performance intermediary switches.
The distribution and core layers comprise high-performance switches, leading to faster speeds and fewer network capacity concerns. As a result, if the network is constructed correctly, data should move at near wire-speed for most of its journey within the network
2. Increased dependability:
The modular architecture of a hierarchical network results in a more dependable network overall since failed or degraded pieces may be separated and routed around. The remainder of the network will remain unaffected.
3. Access layer assistance:
With the development of wireless connection on practically every endpoint, access layer redundancy may be achieved partly by not connecting wireless access points in an area to the same access layer switches as the physical switch ports. In this manner, even if an access switch that provides physical connectivity fails, endpoints may still be able to access the wireless network.
4. Expanded scalability:
The flexibility of hierarchical networks is greater than that of their counterparts, and the network may simply add segments and elements to the network without severely interrupting it. Consistent design from module to module enables network managers to plan and implement network expansion confidently, knowing the topology will remain constant. As a result, networks may grow in lockstep with the enterprise, requiring little to no downtime.
5. Increased security:
Security-wise, a hierarchical network enables a greater degree of control. Access control lists can be more complicated and granular, and traffic can be more effectively bent and prevented. Additionally, these policies may be applied to a single user, a department, or a business, allowing administrators to create network traffic plans according to the enterprise’s needs.
Because most users cannot access network specifics, purposeful or accidental network difficulties become less of a worry, benefiting productivity and network performance.
6. Manageable:
These networks are easier to administer since each layer is designed to perform a specified and consistent purpose. For instance, if you need to adjust the functionalities of an access layer switch, you can reliably edit all the controls in the same way—because they all perform the same job. Additionally, it simplifies the deployment of additional rules since settings may be copied from one device to another without substantial adjustments. Additionally, troubleshooting and recovery are simplified and expedited.
7. Cost-cutting measures:
IT networking equipment is a significant investment. However, hierarchical network architecture can help cut expenses by allowing the business to purchase just what is necessary based on the enterprise’s logical structure. For instance, adding a new department may frequently be accomplished with a single access switch and a few Ethernet cables, rather than requiring a new chain of routers and switches.
