How to achieve true network resiliency
Two leased lines do not automatically create a resilient network. True resilience means identifying every shared component between the customer premises and the provider's core, then removing the single points of failure that matter to the business.
Network diversity versus physical route diversity
Network diversity means using different network operators, exchanges or core platforms. Physical route diversity means the cables follow genuinely separate ducts, chambers, street routes and building entry points. One does not guarantee the other: two providers can share a duct, while two separate fibre routes can still feed the same provider core.
Openreach Resilience Option 1
Openreach Resilience Option 1 (RO1) provides separate fibre paths, but they can use the same cable or duct route. It can protect against failure of an individual fibre or termination component, but a cable cut, duct collapse or major incident on the shared route can still affect both paths.
Openreach Resilience Option 2
Openreach Resilience Option 2 (RO2) is designed to provide two diversely routed circuits with separate network terminating equipment. Openreach avoids common cables and ducts wherever possible, giving protection against a wider range of physical failures than RO1.
RO2 remains subject to survey and feasibility. Local duct layout, available street routes, wayleaves, building entry points, civil-engineering requirements and cost can make complete separation impractical or impossible. The proposed routes should therefore be checked before treating them as fully diverse.
Exchange diversity is another layer
Resilient circuits can be ordered from the same Openreach exchange or from separate exchanges. In a dual-exchange design, the primary leg is normally served from the closest suitable exchange and the secondary leg usually comes from the next closest feasible exchange. The secondary leg will normally attract a main-link distance charge for the additional exchange-to-exchange distance.
If both circuits use one exchange, ensure they terminate on separate equipment, line cards, chassis and power where the provider can support it. Otherwise, one equipment failure can take down both services. Separate exchanges reduce that risk, but the exchanges may still use common backhaul fibre further into the network.
Use different provider core networks
Even when the access routes and exchange backhaul are separate, both services may connect into the same provider core. A major core fault, routing failure or platform outage could therefore affect both circuits.
To remove this shared risk, each leased line should use an independent core path and point of presence. Bletchley Networks offers carrier independence, allowing each circuit to be routed through a different carrier's core network. This reduces the chance that a failure within one provider's core takes down both services.
Mixing access networks
RO2 is an Openreach product. If one circuit uses Openreach and the other uses Virgin Media Business, ITS or another access network, it can be harder to verify end-to-end physical separation. Different operators may use the same street, chamber or Openreach duct infrastructure, and no single operator may be able to certify both routes. In some locations, complete route verification is not possible.
Remove failures inside the customer premises
Two diverse circuits terminated on one managed router or firewall still have a single point of failure. Where uptime justifies it, use separate devices in a high-availability design and test that traffic fails over as expected.
If equipment has redundant power supplies, connect each supply to a separate PDU and, ideally, a separate UPS and ring main. Two power supplies connected to the same electrical source do not provide meaningful power diversity.
Bottom line
True network resilience is layered: diverse fibres, diverse physical routes, appropriate exchange and backhaul separation, independent provider-core paths, resilient customer equipment and independent power. Any shared layer can become the point that defeats the whole design.