Network Design Principles for High Availability and Redundancy

In today's interconnected world, most businesses rely on their networks for data access, services, and uninterrupted communication. Network failures can occur due to various reasons such as hardware failure, disrupted operations, unexpected events, or software glitches. Such failures can result in downtime and financial loss. Therefore, high availability and redundancy play a vital role in building a robust network. The below article covers in detail regarding high availability and redundancy and the network design principles that need to be considered.

What is Meant by High Availability in Computer Networks?

High Availability (HA) is defined as the compatibility of the system for providing services to the users without going down for any time period. High Availability reduces service downtime even in the presence of hardware failure, unresponsive applications, no connection with the cloud provider, etc. Adding redundancy to the system on every level is defined as the best way to increase the high availability. In case of failure of any one component, the entire HA system must remain in an operational state. A High Availability system is used in various applications such as Healthcare devices, self-driving cars, Electronic health records, etc.

Availability can be calculated using below formula:

Availability = (Minutes in a month- Minutes of Downtime)* 100/Minutes in a month

Where, Downtime is a time for which the system is not operational

What is Meant by Redundancy in Computer Networks?

Network redundancy is defined as a process of developing alternative or extra pathways, devices, or other components for business networks in case of any error or failure. Many times network redundancy is considered as a disaster recovery plan because it reduces the chances of damage, errors, and shutdowns.

There are four types of network redundancies as follows:

• Power Redundancy: Power redundancy is defined as a process in which a business is protected in case of power or electricity failure because electricity is required for the network devices to function.

• Data Redundancy: Data redundancy is defined as a process where all the critical and important business related information can be achieved through secondary means or facilities. It helps to protect from loss of data.

• Geographic Redundancy: Geographic redundancy is defined as a process where a business network is spanned at multiple geographical locations. Geographic redundancy is required for reducing the chances of localized events that affects the business data.

• Pathway Redundancy: Pathway redundancy is defined as a process where multiple or alternative network routes are created for various functions. Therefore business are able to perform their operations even if regular connections stop working.

Network Design Principles for High Availability and Redundancy

1. Set up Load Balancer

Load Balancer is used for distributing the overall network traffic across multiple paths, devices or servers instead of sending it to a single server. Using load balancer helps to prevent overloading, reduce the downtime, optimize the performance and improve redundancy. The load balancer selects the best resource among the available resources that is capable of handling the workloads and network traffic. Different types of load balancing algorithms can be used. They are:

• Round Robin: Round robin load balancing algorithm distributes the entire traffic evenly across all the available servers.
• Source IP Hash: Source IP Hash algorithm selects the server according to the source IP address of the request. A unique hash key is being created by the load balancer using source and destination IP address.
• Least Connection: Load balancer that uses least connection algorithm selects the server that has minimum number of active connections.

2. Data Backup and Recovery

Data backup and recovery process is used for minimizing the loss of data in case of failures. A high available system needs to have a plans for data protection and disaster recovery. The business and companies needs to have a backup plans for recovering immediately from failures such as data loss, corruption and recovery. If any organization requires low RTOs and RPOs and cannot afford to lose data using data replication is then considered as one of the best option. If any primary system fails or in case of hardware or software failure the backup setups must have the access to up-to-date the records for smooth and correct backup.

3. Failover Mechanisms

In case of any hardware or software related failure, entire system or a specific failure, failover must be available in real time, within less time and without any manual intervention. For example, the setup consists of two devices namely machine 1 and machine 2 also known as Hot Spare. Machine 2 continuously monitors the machine 1 for any kind of sudden errors or issues. If primary machine that is machine 1 fails for further operation after a sudden error, machine 2 comes online and becomes available in place of primary machine. This process takes place without any impact or disturbance for the end users. Once the admin will resolve the problem with machine 1, machine 2 goes offline and machine 1 again acts as a primary machine.

4. Choosing Appropriate redundancy protocol

There are multiple redundancy protocols, but not all the protocols are robust. Therefore there is a need to select proper and appropriate protocol for the network. The efficient and reliable protocols have simple configuration on the devices. Below are the appropriate and efficient protocols:

Layer 1 and 2 Redundancy Protocols

• Link Aggregation Control Protocol(LACP): Link Aggregation Control Protocol(LACP) is used for link redundancy and has various multi-chassis variants.
• Spanning Tree Protocol (STP): Spanning Tree Protocol(STP) is used as it has a modern fast converging variants such as RSTP and SMTP.

Layer 3 Redundancy Protocols

• Cisco’s proprietary Hot Standby Routing Protocol (HSRP):Cisco’s proprietary Hot Standby Routing Protocol is used for end devices such as workstations and servers.
• Dynamic routing protocols: Dynamic routing protocols such as OSPF, EIGRP, or BGP for interconnecting network devices.

5. Security measures

It is necessary to implement the security features against the threats that can reduce the high availability. In order to prevent from various cyberattacks there various security measures that needs to be followed. They are:

• Installing firewalls: Firewall acts as a barrier between the internal network of the company and the traffic that comes from external sources. It blocks the malicious content, viruses and provides security for the systems.
• Training employees: The employees working in the organization or business teams needs to educated regarded the security measures that needs to be followed such as setting a strong passwords, contingency plans in case of network failures etc.
• Securing Wi-Fi networks: The Wi-Fi networks used needs to protected with the help of passwords. Even Wi-Fi networks can be hidden by setting up the router so that it will not broadcast the name of network or SSID.
• Controlling access to company devices: Controlling access prevents the company devices from being used by unauthorized entities. It makes sure that the devices are locked when they are not in use.

6. Regular Testing and Documentations

Regular testing consists of checking for failover and load testing to make sure that failover mechanisms works according to the implementation and expectations. Maintenance of regular documentations is required for troubleshooting and recovery processes in future. It helps to easily debug and identify the errors and solve them accordingly.