Building redundancy into a network mostly improves reliability and availability, but it also adds cost and complexity that you have to manage carefully.

What “redundancy” means in a network

Network redundancy means adding extra links, devices, or paths so that if one component fails, another automatically takes over and traffic keeps flowing.

Examples include dual ISPs, multiple core switches, redundant firewalls, or diverse fiber routes between sites.

Benefits of building redundancy

1. Higher availability and less downtime

  • Redundant links and devices allow traffic to fail over automatically when a primary path or device fails, keeping services online instead of causing an outage.
  • This is crucial for 24/7 environments (hospitals, banks, e‑commerce, SaaS) where even short outages can mean lost revenue or safety issues.

2. Improved reliability and resilience

  • Extra paths eliminate single points of failure, so a single router, switch, or circuit going down does not take the entire network offline.
  • Redundancy also helps in disaster scenarios (fiber cut, power failure, localized incident), allowing traffic to reroute around the affected area.

3. Better performance and load balancing

  • With multiple active paths, you can load‑balance traffic across links, reducing congestion and improving throughput and latency.
  • During peak periods, this helps maintain consistent speeds rather than overloading one link while others sit idle.

4. Stronger business continuity

  • Redundant WAN, data center, and critical services (DNS, DHCP, VPN, authentication) help keep core business operations running even if one site or provider fails.
  • That translates to better customer experience and less operational disruption when things go wrong.

5. Security and maintenance advantages

  • Redundant networks support more robust security architectures (e.g., active/standby firewalls or dual DDoS‑protected upstreams), so security incidents are less likely to cause total outages.
  • Planned maintenance can be done on one path or device while traffic uses another, reducing the need for maintenance windows and visible downtime.

Potential issues and downsides

1. Higher cost (CapEx and OpEx)

  • Redundancy means paying for extra circuits, hardware (switches, routers, firewalls), licenses, and support contracts.
  • Operating costs rise too: more equipment to power, cool, monitor, patch, and replace over time.

2. Increased design and operational complexity

  • Designing redundant topologies (dual core, multiple uplinks, routing failover, spanning‑tree tuning, VRRP/HSRP, etc.) requires careful planning and expertise.
  • Misconfigurations in routing, failover timers, or load‑balancing policies can cause loops, flapping routes, or asymmetric paths that are hard to troubleshoot.

3. “False sense of security” and hidden single points of failure

  • If redundancy is not truly end‑to‑end (e.g., two links in the same conduit or two “redundant” devices on the same power feed), a single failure can still break everything.
  • Poorly tested failover can appear redundant on paper but fail in practice when an actual outage occurs.

4. More failure modes to manage

  • Additional devices and links increase the number of components that can fail or misbehave, introducing new types of partial failures and intermittent issues.
  • Edge cases such as split‑brain scenarios or inconsistent routing tables can be triggered by poorly coordinated redundancy.

5. Performance side effects if misconfigured

  • Aggressive or poorly tuned failover mechanisms can cause route flapping or frequent reconvergence, degrading application performance.
  • Load‑balancing without awareness of application flows can lead to packet reordering or asymmetric routing, which some applications and security tools dislike.

When redundancy makes sense (and how much)

  • Critical services (payments, healthcare, industrial control, customer‑facing platforms) usually justify multiple layers of redundancy across links, hardware, and sites.
  • Smaller or less critical environments often use “right‑sized” redundancy: for example, dual WAN links but not fully duplicated access switches in every closet.

A simple way to frame it: match the level of redundancy to the business impact of downtime and your team’s ability to design, test, and operate that extra complexity.

Quick TL;DR

  • Main benefits: higher availability, better reliability, improved performance, stronger business continuity, safer maintenance windows.
  • Main issues: higher cost, more complexity, potential misconfigurations, hidden single points of failure, and tricky failure modes if not carefully designed and tested.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.