Peering, IP transit and BGP: connecting your data center right
Connecting a data center to the internet means choosing between buying connectivity (transit) and exchanging it (peering), then making it resilient with your own network number and BGP. Here, without jargon, is how it works and where the real traps are.
Transit and peering: the difference #
Transit means buying access to the whole internet from a carrier. Peering means exchanging traffic directly with another network, often through an internet exchange (IXP). Transit is complete but paid; peering cuts cost and latency on part of your traffic. You combine the two.
Your identity: ASN and IP addresses #
An ASN (autonomous system number) is obtained from your regional registry (the RIPE NCC in Europe). With IPv4 exhausted, you go through the transfer market or a LIR that sponsors your resources. With your own ASN and addresses, your addressing no longer depends on the carrier.
Multi-homing and BGP #
Multi-homing means connecting to several carriers over BGP. If one goes down, the other takes over: it is the foundation of network resilience. You still need an offer that allows BGP announcement of your prefixes.
How transit is billed #
Transit is priced by throughput, in euros per Mbps or Gbps, often measured at the 95th percentile: the top 5% of peaks are dropped. Watch volume commitments and tiers. A price means nothing without its measurement method.
Not all transit is equal #
The quality of transit depends mostly on who it reaches well. A cheap but congested carrier toward a major destination (a cloud giant, a large host) degrades latency and throughput at peak hours. The fix is several genuinely diverse carriers.
RPKI: filtering bad routes #
RPKI validates the origin of BGP routes and lets you reject invalid announcements, which often signal a leak or a hijack. A serious carrier filters invalid routes. Check this before signing.
IPv6: don't sideline it #
IPv6 transit must be genuinely good, not relegated behind IPv4. Check parity between the two: more and more traffic runs over IPv6, and a degraded v6 shows in daily use.
What to check #
Who is actually present in the data center (carriers, exchanges), whether the offer allows BGP announcement, the billing model (95th percentile, commitments), RPKI filtering, IPv6 quality, and real carrier diversity. These answers are worth more than a headline speed.
FAQ #
Not for simple use, but yes to be portable and to multi-home. Without your own ASN and addresses, switching carriers forces a full renumbering.
Because its quality depends on who it reaches well. A carrier congested toward a major destination degrades latency and throughput at peak hours. The fix: several diverse carriers.
A system that validates the origin of BGP routes and lets you reject invalid announcements, reducing traffic leaks and hijacks. Check that your carrier filters invalid routes.
Written on 1 September 2026.
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