Key Points
- Redundant internet connections reduce dependency on a single ISP and mitigate downtime risks.
- BGP automates failover by dynamically rerouting traffic when a primary link fails, avoiding major disruption.
- Implementing BGP redundancy requires public IP addressing, continuous monitoring, and routing policies to be configured and validated.
Network connectivity issues have a significant impact on enterprise activities and customer satisfaction, particularly for organizations relying on a single Internet Service Provider (ISP).
To avoid indefinite downtimes and costly disruptions, MSPs and IT teams can use Border Gateway Protocol (BGP) to set up redundant internet connections, which will help ensure continuous uptime for critical business operations.
Border Gateway Protocol explained
Cloudflare describes BGP as the “postal service of the internet”, highlighting the protocol’s role in network connectivity. But how does it actually work?
At the risk of oversimplification, the Internet consists of hundreds of thousands of autonomous systems (AS). BGP connects these ASes using complex algorithms to identify and facilitate an efficient data exchange at any given time.
For instance, when multiple paths exist, BGP follows a strict decision sequence, which varies depending on the vendor. Below is a typical Cisco-style order hierarchy:
| Priority | Attribute |
| 1 | Weight (Cisco-only parameter) |
| 2 | Local Preference |
| 3 | Originate |
| 4 | AS path length |
| 5 | Origin code |
| 6 | MED |
| 7 | eBGP path over iBGP path |
| 8 | Shortest IGP path to BGP next hop |
| 9 | Oldest path |
| 10 | Router ID |
| 11 | Neighbor IP address |
The ideal path will be prioritized by BGP based on the criterion, with the most influential attributes in typical enterprise environments being: Weight, LOCAL_PREF, AS_PATH, MED. Notably, Weight is a Cisco-proprietary attribute. You may omit this criterion if you’re using another provider.
Example of a BGP path selection scenario
Let’s say a router receives two routes to 203.0.113.0/24:
| Attribute | Path A | Path B |
| Weight | 0 | 0 |
| LOCAL_PREF | 200 | 100 |
| AS_PATH | 65001 65002 | 65003 |
| MED | 50 | 10 |
Even though Path B has a shorter AS_PATH and lower MED, Path A wins because LOCAL_PREF is evaluated earlier.
How to set up BGP-based redundancy
To implement BGP-based redundancy, your tech environment needs a BGP-capable router/firewall. Cisco ASR, Juniper MX, and Fortinet FortiGate are some of the enterprise-grade hardware that fit these requirements.
A trip to the Regional Internet Registry or ISP might also be in order, if you have yet to secure a block of public IPs for global routing and a unique Autonomous System Number (ASN), which should be assigned to your network.
Here’s a high-level checklist on how to design for BGP-based redundancy:
- Deploy a BGP-capable router.
- Obtain a public IP block (from RIR or ISP).
- Acquire ASN from the designated RIR.
- Select two or more ISPs with BGP peering support.
- Configure BGP neighbors for each ISP.
- Obtain ISP-specific BGP configuration details.
- Set route advertisement policies and controls (for example, prefer ISP A, failover to ISP B).
A network monitoring system should also be added to the pipeline to account for scale and efficiency. For example, alerts can be added through NinjaOne to track route flapping, which is a common disruptor in BGP-based workflows.
Discover more ways to improve network resiliency
Using redundant internet connections with BGP is one of the most reliable ways to strengthen network infrastructure. It also utilizes key IT activations like backup ISP, network policies, and system monitoring, which enables many enterprise IT teams and MSPs to become early adopters.
On the other hand, companies that are in transition can implement incremental improvements such as failover testing, policy refinements, and monitoring enhancements to ensure operational readiness. SD-WAN integration and DDoS protection also provide a good starting point, typically, with more manageable overhead and technical requirements.
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