Skip to content

Internet Topology and BGP Relationships

Run the Internet Topology and BGP Relationships MicroSim Fullscreen

About This MicroSim

s:

This MicroSim is built with vis-network and is width-responsive, so it adapts to the width of the page or container it is embedded in.

How to Use

Use the controls in the panel below the drawing area to explore the concept. Adjust the sliders, toggle the options, and step through the stages to see how each change affects what is shown.

Specification

The full specification below is extracted from Chapter 10: Routing and Forwarding.

Type: microsim
**sim-id:** internet-topology-bgp<br/>
**Library:** vis-network<br/>
**Status:** Specified

Render an interactive node-link diagram of a small Internet showing autonomous systems and the BGP relationships between them.

Canvas: 960 px wide by 620 px tall, responsive down to 360 px.

Topology:

- 4 tier-1 ISPs at the top, fully meshed with peering links.
- 6 tier-2 ISPs in the middle, each connected to one or two tier-1s via transit, and to several other tier-2s via peering.
- 8 tier-3 ISPs and content providers at the bottom, each with one or two transit providers.
- Special nodes: a tier-1 anchored CDN (e.g., Cloudflare, AS 13335) directly peering with most others; a major content network (e.g., Google, AS 15169) with many peering links.

Edge styles:

- Transit links: thick honey-amber arrows pointing from customer to provider; transit traffic flows in both directions.
- Peering links: dashed slate edges, no arrow direction.
- Each link has a hover tooltip showing the relationship type and the typical traffic volume.

Interactivity:

- Click any AS to see its full set of relationships and the AS path it would use to reach any other AS in the diagram.
- Click any pair of ASes (source and destination) to highlight the BGP-preferred path in green and other available paths in dim gray.
- Toggle "Hide transit relationships" to show only peering links — useful for understanding the dense peering mesh among large networks.
- "Add IXP" toggle introduces a virtual IXP node to which many ASes connect; demonstrate that one IXP can replace dozens of pairwise peering links.

Visual style:

- Tier-1 ASes: rounded rectangles in deep slate.
- Tier-2 ASes: rounded rectangles in mid-slate.
- Tier-3 ASes / content: rounded rectangles in honey amber.
- Currently-selected path: green highlight.

Learning objectives:

- (Bloom — Understanding) Students explain the difference between peering and transit relationships.
- (Bloom — Analyzing) Students decompose a BGP-preferred AS path into its commercial relationships.
- (Bloom — Evaluating) Students judge how IXPs and direct peering with content providers reduce transit costs and improve performance.

Implement in vis-network with the existing learning-graph viewer styling.

Iframe Embed Code

You can add this MicroSim to any web page by adding this HTML:

<iframe src="https://dmccreary.github.io/networking/sims/internet-topology-bgp/main.html"
        height="502px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Learning Objective

s:

Bloom Taxonomy Level

Understand

Suggested Classroom Use

  1. Predict — Ask students to predict the behavior before they interact.
  2. Explore — Have students manipulate the controls and observe the results.
  3. Explain — Ask students to explain, in their own words, what they observed and how it connects to routing and forwarding.

References