Cogent DIA vs IP transit, and what its peering disputes mean for you

Cogent quotes come up in two very different conversations. An office manager in a downtown tower gets a Cogent DIA quote that is a few hundred dollars under everyone else. A network engineer in a colocation cage gets a Cogent transit quote at a per-megabit rate that makes the other carriers look expensive. Both are buying the same backbone. They are not buying the same product, and the risks they take on are not the same either.

This post covers what separates Cogent's Dedicated Internet Access from its IP Transit, what Cogent's published SLA does and does not cover, and how its long history of peering disputes should shape the way you buy it.

The same backbone, sold two ways

Cogent runs AS174, one of the largest internet backbones in the world. It sells access to that backbone as two products. We summarize its current terms on our Cogent carrier page.

Dedicated Internet Access (DIA) is internet for a site. Cogent sells it at 100 Mbps, 1 Gbps, 10 Gbps and 100 Gbps, delivered only over fiber, into about 1,870 multi-tenant office buildings and more than 1,600 carrier-neutral data centers on its network (Cogent’s counts as of September 30, 2026). You get a reserved, symmetrical port and a block of Cogent IP addresses. In an office building, routing is usually static; BGP and link aggregation are standard in data centers, and Cogent says to check with an account manager for office buildings.

IP Transit is internet for a network. It is sold mainly in data centers, cable landing stations and other high-traffic sites, on ports from 100 Mbps up to 400 Gbps. You bring your own IP space and autonomous system number, run BGP (Cogent supports multiple BGP sessions on one port), and Cogent carries your routes to the rest of the internet.

If you do not have an ASN and do not plan to get one, you are buying DIA. If you are multihoming your own prefixes, you are buying transit, even if the salesperson calls it DIA with BGP. Our dedicated internet access guide and IP transit guide compare both across carriers.

What the Cogent SLA covers, and what it does not

Cogent publishes its SLA, which is more than many carriers do. The headline is 100% network availability, 99.9% packet delivery and a 45 ms round-trip latency target within North America. The details are what matter:

• On-net outages earn real credit. After 15 consecutive minutes down, you earn one day of credit (1/30 of the monthly charge) for every cumulative hour of outage, capped at one month.

• Off-net outages earn much less. If Cogent reaches you over another carrier's local loop, you earn one hour of credit per hour down. A four-hour outage is worth about four days of credit on-net and about four hours of credit off-net.

• Cable cuts are excluded. The SLA treats cable cuts as force majeure, so the most common cause of a long outage does not count against the 100% figure.

• Performance is measured hub to hub. Latency, jitter and packet delivery are averaged between Cogent backbone hubs, not to your router.

• Claims are on a short clock. You have seven business days after month end to request credit, and you need a ticket opened during the event.

None of this makes Cogent a bad buy. It means the SLA is a pricing instrument, not a resilience plan. The resilience has to come from your design.

The peering question

Large backbones reach each other through peering: two networks agree to exchange traffic directly, usually without payment. Cogent built its low-price model on settlement-free peering, and it has been willing to cut off peers when it disagrees about who should pay for capacity. The public record includes disputes with Level 3 (2005), Telia and Sprint (2008), Deutsche Telekom (2015, which ended in litigation), NTT and Tata Communications (2024). Cogent and Hurricane Electric have not peered over IPv6 since 2009.

Most of these were resolved, some within weeks. But during a dispute, a Cogent-only customer can find that a slice of the internet is slow or unreachable, and nobody owes them a credit for it, because Cogent's own network is up.

How much this matters depends on which product you bought:

• DIA as your only circuit. This is the most exposed position. If Cogent and a large network stop exchanging traffic, your office has no other way to reach the affected destinations until the dispute ends. You cannot route around it.

• DIA as one of two circuits. Much safer. With a second carrier and either BGP or an SD-WAN edge that can steer traffic, a peering problem on one side becomes a performance blip instead of an outage.

• IP transit as one of several upstreams. This is how most networks buy Cogent, and it is the use case Cogent's pricing is built for. If one upstream cannot reach a destination, BGP finds another path.

IPv6 deserves its own test

Cogent supports native IPv6 and dual stack on both products. The open Hurricane Electric dispute is the reason to test before you rely on it. Reports on the NANOG operators' list since 2009 describe IPv6 routes between the two networks as missing or indirect at various times. If your business serves users over IPv6, or you have partners on Hurricane Electric, check reachability to the destinations that matter before go-live, and keep a second IPv6-capable upstream.

When Cogent is the right call

We recommend Cogent often. The pattern where it works best:

• You are in a Cogent-lit building. On-net, Cogent is usually one of the lowest prices we see at 1 Gbps and above, and its published install commitment is 17 business days.

• It is one of two paths. Paired with a carrier that has a different backbone and, ideally, a different building entrance, such as Lumen or Zayo.

• You need cheap capacity in a data center. For transit, Cogent's price per megabit is hard to beat, and multihoming is standard practice. Transit prices also keep falling (TeleGeography’s 2026 analysis puts the drop for 100 GigE ports at about 17% a year), so price the commit against at least two upstreams.

And the pattern where we steer clients elsewhere:

• One circuit, one office, no fallback. Pay a little more for a single carrier with fewer peering disputes on record, or add a second circuit.

• Off-net addresses. Cogent off-net loses its price edge, waits up to 90 business days to install, and pays much smaller credits.

• You want a bundle. Cogent sells a lean product. Managed security, voice and SD-WAN are better bought from carriers that specialize in them.

Questions to ask before you sign a Cogent quote

1. Is this address on-net or off-net, and which SLA credit schedule applies?

2. In an office building, will Cogent support BGP and LAG on this port? Put it in the order.

3. How many IPv4 addresses are included, and what does a larger block cost?

4. Which building entrance and riser does Cogent use, and does it share either with my other carrier?

5. Was installation waived? If so, there is no credit for a late install.

6. For transit: what is the commit, how is burst billed, and is there a 95th percentile calculation?

7. What are the term, auto-renewal and early termination terms in the order form? Our note on auto-renewing a 36-month term covers the renewal window.

For transit buyers, also ask how Cogent's routes reach the networks that carry most of your traffic. A looking glass check (Cogent publishes one) takes five minutes and tells you more than any brochure.

Frequently asked questions

What is the difference between Cogent DIA and Cogent IP transit?

Cogent DIA is internet for a site: a reserved, symmetrical port with Cogent-assigned IP addresses. Cogent IP transit is internet for a network: you bring your own IP space and ASN, run BGP, and Cogent carries your routes to the rest of the internet.

Do I need IP transit or dedicated internet?

If you do not have an ASN and do not plan to get one, you are buying DIA. If you are multihoming your own IP prefixes, you are buying transit.

What does Cogent’s SLA cover?

Cogent publishes 100% network availability, 99.9% packet delivery and a 45 ms round-trip latency target within North America. On-net outages earn far more credit than off-net ones, cable cuts are excluded as force majeure, and credit claims are due within seven business days after month end.

What are Cogent’s peering disputes?

Cogent has cut off peers in disagreements over who pays for capacity, including disputes with Level 3, Telia, Sprint, Deutsche Telekom, NTT and Tata Communications. It has not peered with Hurricane Electric over IPv6 since 2009. During a dispute, some destinations can be slow or unreachable for Cogent-only customers.

Is it safe to use Cogent as my only internet circuit?

That is the most exposed position, because you cannot route around a peering dispute. Cogent works best as one of two circuits, paired with a carrier on a different backbone, or as one of several transit upstreams.

How long does Cogent take to install?

Cogent’s published install commitment is 17 business days on-net and up to 90 business days off-net.

What we do for you

We check your address against Cogent’s lit-building and data center lists, and against every other carrier lit in the same building. If Cogent is the right primary or the right second path, we quote it with the questions above already answered, and if it is not, we tell you why. Send us the address and we will put Cogent next to the alternatives on the same terms.