Peering

Networking

Direct network interconnection between two autonomous systems, bypassing transit providers. Reduces latency and cost. CDNs peer aggressively at IXPs and private interconnects to shorten the path between edge servers and end users.

Updated Mar 9, 2026

Full Explanation

Peering is when two networks agree to exchange traffic directly instead of routing through a third-party transit provider. It's usually settlement-free (neither side pays the other) and happens either at Internet Exchange Points (public peering) or via dedicated cross-connects in data centers (private peering).

For CDNs, peering is a core business strategy. The more ISPs a CDN peers with, the fewer network hops between the edge server and the end user. Fewer hops means lower latency, less jitter, and reduced packet loss. Large CDNs like Akamai, Cloudflare, and Fastly peer with thousands of networks globally.

Peering also reduces costs. Transit bandwidth (buying capacity from a Tier 1 provider) is expensive. Peering lets CDNs bypass that cost for a significant portion of their traffic. Some CDNs even colocate servers inside ISP networks—the ultimate form of peering—putting content just one hop from end users.

Examples

Checking the AS path to see peering vs. transit:

# View BGP path to a CDN
traceroute -a cdn.example.com

# Check peering info on PeeringDB
curl -s "https://www.peeringdb.com/api/net?asn=13335" | python3 -m json.tool | head -20
# (AS13335 = Cloudflare)

Viewing IX peering on a looking glass:

# BGP community tags often indicate peering type
# Example: route from AS-PATH shows direct peering (single hop)
$ show bgp 104.16.0.0/12
  AS Path: 13335 i   # direct peer, no transit

# vs transit route (multiple ASes)
  AS Path: 3356 13335 i   # via Level3 transit

Video Explanation

Frequently Asked Questions

Direct network interconnection between two autonomous systems, bypassing transit providers. Reduces latency and cost. CDNs peer aggressively at IXPs and private interconnects to shorten the path between edge servers and end users.

Checking the AS path to see peering vs. transit:

# View BGP path to a CDN
traceroute -a cdn.example.com

# Check peering info on PeeringDB
curl -s "https://www.peeringdb.com/api/net?asn=13335" | python3 -m json.tool | head -20
# (AS13335 = Cloudflare)

Viewing IX peering on a looking glass:

# BGP community tags often indicate peering type
# Example: route from AS-PATH shows direct peering (single hop)
$ show bgp 104.16.0.0/12
  AS Path: 13335 i   # direct peer, no transit

# vs transit route (multiple ASes)
  AS Path: 3356 13335 i   # via Level3 transit

Related CDN concepts include:

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