BGP Interdomain Policy Calculator

Formula Used

This calculator uses a weighted planning score inspired by common interdomain routing priorities.

Policy Score = (Weight × 10) + Local Preference + Relationship Bonus + Origin Bonus + Community Bonus + RPKI Bonus − (AS Path Length × 15) − (MED × 0.10) − (Latency × 0.20)

Important: Real BGP selection is vendor specific and step based. This formula is a practical comparison model for planning, design review, and policy discussions.

How to Use This Calculator

1. Enter three candidate route names.
2. Fill local preference, weight, AS path length, and MED values.
3. Select the origin type for each route.
4. Choose whether the route is from a customer, peer, or provider.
5. Add any community bonus that matches your internal routing policy.
6. Set the RPKI state and latency penalty input.
7. Click Calculate Policy to rank the routes.
8. Review the preferred route and export the result table as CSV or PDF.

Example Data Table

BGP Interdomain Policy Planning

A BGP interdomain policy calculator helps engineers compare route choices before deployment. It turns policy ideas into a repeatable score. That makes reviews easier. It also reduces routing surprises. Teams can test how local preference, AS path length, MED, origin, communities, and security signals change route ranking.

Interdomain routing is never based on one metric alone. Operators often prefer customer paths, trusted origins, and valid announcements. They also avoid long paths, weak security, and poor exit metrics. This calculator models those tradeoffs with a transparent formula. It does not replace router logic. It supports design, planning, training, and documentation.

Why This Calculator Matters

Policy drift can create inconsistent routing decisions across regions. A scoring worksheet gives every engineer the same baseline. You can compare three candidate routes at once. You can also see why one path wins. That is useful during peering reviews, migration work, failover planning, and traffic engineering analysis.

Because BGP policy depends on business goals, the calculator includes relationship bonuses and community adjustments. Customer routes can receive a stronger bonus. Peer routes can stay moderate. Provider routes can stay lower. RPKI state can also change the result. That helps teams give extra trust to valid routes and heavy penalties to invalid ones.

Useful Inputs for Better Decisions

Local preference remains a strong signal in many networks. Weight can model device specific preference. AS path length reflects reachability cost. MED can represent exit hints from neighbors. Origin type adds basic route quality context. Community bonus supports internal policy tags. Latency penalty gives the model a performance check for user experience.

Use this page when you need a fast BGP route comparison tool, an interdomain routing planner, or a policy scoring worksheet. The output is easy to export. That makes it helpful for change records, design notes, and audit trails. Clear route scoring improves review speed and strengthens network operations.

The calculator is especially helpful when documenting routing policy for new peers or upstreams. Instead of debating abstract preferences, teams can compare concrete values. That creates cleaner approvals. It also helps junior engineers learn how multiple attributes influence a final routing outcome.

FAQs

1. What does this BGP interdomain policy calculator do?

It compares three candidate routes with a weighted scoring model. The result highlights the route that best matches your preference, path quality, relationship, security, and latency assumptions.

2. Is this the same as a router’s exact decision process?

No. It is a planning calculator. Real devices follow step based logic and vendor specific behavior. This page helps you model policy intent before live deployment.

3. Why is local preference so important here?

Local preference is often one of the strongest internal route controls. A higher value usually means the network should prefer that path across the AS.

4. Why does the calculator penalize long AS paths?

Longer AS paths can suggest less direct reachability. The penalty helps reflect operational preference for shorter and often cleaner paths during route comparison.

5. What is the relationship bonus used for?

It lets the model favor customer routes over peer or provider routes. That mirrors many commercial and traffic engineering policies used in interdomain routing.

6. How does RPKI affect the result?

Valid announcements receive extra trust. Unknown routes get a smaller benefit. Invalid announcements receive a heavy penalty to reflect stronger security caution.

7. Can I use this for traffic engineering discussions?

Yes. It is useful for peering reviews, migration planning, path ranking, and documentation. It gives teams a simple way to compare policy scenarios quickly.

8. What should I export with the CSV or PDF options?

Export the ranked result table after calculation. That file works well for change records, review notes, peer discussions, and policy approval documents.