This is Part 1 of a short series on Internet Exchange Points (IXPs) and why being “closer” to an IXP—measured in degrees of separation (hops)—is often a practical proxy for network quality.

If you’ve heard “Six Degrees to Kevin Bacon,” this is the same idea applied to networks: instead of asking how many co‑star links connect an actor to Kevin Bacon, we ask how many network hops connect a home/business (via its local infrastructure) to the nearest IXP. That “IXP number” can be defined in multiple ways (logical, physical, weighted), but the intuition is the same: fewer steps usually means easier, higher quality access.

In network infrastructure, degrees of separation refer to the number of intermediate hops—both physical and logical—between a secondary distribution node (like a school switch or neighborhood fiber cabinet) and an Internet Exchange Point (IXP). These degrees impact network quality in measurable ways, particularly performance, resilience, bandwidth efficiency, and autonomy.

Spatial Layers in the Network Path

Layer Example Role in Separation
Premises / Endpoint Home router, small business gateway, school LAN Where demand originates; separation is measured from here outward
Local Access / Distribution Neighborhood cabinet, OLT, school switch First shared infrastructure; often the first “step up” from a single site
Aggregation Node Township/city hub, county POP Consolidates multiple access domains; a common place where paths become constrained
Regional Core Metro ring, regional datacenter/router High-capacity routing across a region; where multiple aggregation paths interconnect
Internet Exchange Point (IXP) Equinix, DE-CIX, regional/state IXP Peering fabric for exchanging traffic; typically the boundary between access and global

Each layer introduces a spatial and logical hop. Fewer hops = better performance.

Three ways to measure “separation”

In network analysis, “degrees of separation” is essentially distance in a graph —but in infrastructure work it helps to be explicit about which distance you mean. For IXP planning, there are three complementary definitions:

  • Logical (routing) hops: Router-level or AS-level hop count to an IXP. This captures policy/peering structure and upstream dependencies.
  • Physical (infrastructure) hops: Site/PoP/metro-layer transitions to an IXP. This captures where facilities and fiber aggregation actually occur.
  • Weighted distance (experience): Shortest path where edges are weighted by latency, congestion, cost, or risk. This best reflects what homes and businesses feel.

You often want all three: if they disagree, that disagreement is usually diagnostic (e.g., a low-hop route that still has high latency suggests a long physical path or a routing detour).

Why It Matters

  • Latency: Each hop adds delay. More separation = higher latency.
  • Resilience: More hops = more potential points of failure.
  • Bandwidth Efficiency: Shorter paths reduce congestion and packet loss.
  • Autonomy: Fewer dependencies on upstream providers.

Spatial Thinking in Practice

You can model this using:

  • Network graphs with weighted edges (e.g., latency, bandwidth)
  • GIS overlays showing fiber routes, IXPs, and community nodes
  • Semantic triples like:
    • Node_A —[connected_to]→ Node_B
    • Node_B —[distance_to]→ IXP_X = 3 hops

This enables semantic-aware planning: prioritize upgrades where separation is highest and impact is greatest.

Community Impact

For smart schools, libraries, and public safety systems:

  • Low separation → faster cloud access, real-time video, emergency alerts
  • High separation → bottlenecks, especially in rural or underserved areas

Urban cores may be 2–3 hops from an IXP; rural areas may be 5–7 hops away.

Measuring equity (homes + businesses)

If the goal is not just “better on average,” but more equitable connectivity, it helps to treat network quality as a distribution across homes and businesses.

Credit: I learned the Gini coefficient framing and the HĂĄjek estimator approach for weighted estimation from Dr. Stilian Stoev (University of Michigan Statistics Department).

At the smallest planning scale (townships/cities), you can compute a local metric (e.g., median latency to the nearest IXP, or expected hop-count to the nearest IXP) and then evaluate how unevenly that metric is distributed across places.

  • Gini coefficient (inequality): A compact way to summarize whether a small set of townships/cities carry most of the “distance-to-IXP burden.”
  • Weights (representation): Weight township/city metrics by the number of homes + businesses so the results reflect people and commerce—not just where measurement points happen to exist.

Summary

Network quality is spatially dependent. Reducing degrees of separation between local nodes and IXPs improves:

  • Speed
  • Reliability
  • Autonomy
  • Equity

This concept is essential for resilient digital infrastructure, especially in education, public safety, and community broadband planning.

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