BitTorrent Swarm & Peer Tit-For-Tat Network Simulator

Cytoscape.js P2P Engine

P2P Swarm Topology Map

Tick: 0
Seeders (100%)
Active Leechers
Free-Riders (Choked)
Active Upload Link

Swarm Piece Distribution Matrix

16 Pieces / File
Piece Availability Heatmap (Swarm-wide Rarity) Status: Stable

Swarm Presets & Parameters

Capacity-Ranked Upload Permissions
Rarest-First Piece Scheduling

Swarm Performance Telemetry

Allowed-Link Score 91.4% Capped permission-count formula
Free-Rider Exclusion 84.0% No permission from incomplete peers
Remaining-Piece Proxy 42.5 units Missing copies × 0.85 units
Authored Availability Label Stable Min piece count: 2
Swarm State & Telemetry Summary

Authored piece model. Inspect the matrix for possession and the labels for each metric formula.

BitTorrent Swarm & Peer Tit-For-Tat Network Simulator • Powered by Cytoscape.js & Authored Piece-Possession Model

Separate upload permission from piece progress

Can an allowed upload link be counted as a successful transfer?

Inspect the piece matrix after each step. An unchoked link permits a request, but a transfer requires that the sender has the chosen missing piece. The link score can stay high even when no useful piece moves.

This is an authored Boolean-piece model. Upload values are fixed rankings, not observed contribution rates. There are no file bytes, integrity checks or measured network times.

Try a worked example

With 20 peers and four outgoing permissions each, there are 80 allowed links. The score computes 100 × 80 / 80 + 40, then caps at 98.5%. It stays 98.5% even when all peers have finished and no new piece moves. Separately, ten missing peer-piece copies produce a completion proxy of 8.5 units; that is a formula, not a timed forecast.

Read the four telemetry rules

Allowed-link score = min(98.5, 100 × allowed links / (4 × peer count) + 40). Free-rider exclusion counts free riders with no incoming permission from an incomplete peer; complete peers are excluded. When no free riders exist, the display defaults to 100%, rather than measuring suppression.

Remaining-piece proxy = 0.85 × missing peer-piece copies. Availability is Critical at zero minimum copies, At Risk at one or two, and Stable at three or more. These are authored categories, not reliability probabilities.

Compare scheduling with actual possession

Capacity-ranked mode selects the three highest fixed upload values plus a rotating remaining peer. Random mode reshuffles candidates. Neither measures what a peer recently sent to this particular receiver. Rare-first sorts globally missing pieces, then checks the permitted uploaders; an unavailable selection can stall that receiver for a tick.

Real peer messages distinguish choking and interest, advertise possession, and announce a piece after its hash is checked. Use the protocol specification to understand those states; it does not validate this page’s score or time proxy. BEP 3: BitTorrent Protocol Specification

Sources and further reading
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