Border Gateway Protocol (BGP)

BGP exchanges route information between separately managed networks, helping routers decide how traffic reaches internet, cloud and enterprise destinations using defined path and policy controls.

Routers advertise reachable destinations and path details to connected peers, then routing policies determine which routes are accepted, preferred or passed on. This gives organisations more control over external connectivity than relying only on automatic shortest-path decisions.

OSPF usually selects routes inside one organisation’s network, while BGP manages how routes are exchanged with providers, cloud platforms and other external networks.

They solve different routing problems and are often used together rather than as alternatives. OSPF reacts to changes within the internal estate, while BGP applies business and connectivity policy at external boundaries where provider control and route advertisement matter.

BGP lets organisations advertise their network through multiple internet providers and redirect traffic when a preferred provider or connection is no longer available.

It can also influence which provider carries inbound and outbound traffic during normal conditions. Steel City Consulting can assess address ownership, provider services, physical diversity and failover policy so separate circuits deliver genuine resilience rather than sharing hidden dependencies.

BGP selects routes by comparing available paths against routing information and locally defined policies, choosing the option that best matches organisational connectivity priorities.

Those policies can favour a provider, a shorter network path or a preferred exit point rather than simply the nearest route. Careful design is important because one policy adjustment can change traffic behaviour across sites, cloud links or internet providers.

Organisations secure BGP through controlled peer connections, route filtering, prefix validation and monitoring that identifies unexpected or unauthorised changes to advertised destinations.

Authentication, route limits and origin validation can add further protection where supported. Steel City Consulting can design these controls around connected providers and services, reducing the risk of route leaks or configuration errors affecting internet-facing applications and business connectivity.

Before deploying BGP, assess routing objectives, provider requirements, address ownership, platform capacity, failover expectations and the operational support needed to manage external routing.

Route policies, filtering, monitoring and change controls should also reflect how traffic needs to behave during normal operation and outages. Steel City Consulting can design and test these scenarios before deployment, reducing avoidable connectivity risk and making external routing easier to manage.