OC3 Connection
An OC3 connection is an enterprise-grade optical circuit that delivers 155 Mbps of dedicated bandwidth over SONET fiber or dark fiber. Also written OC-3, it provides symmetrical, SLA-backed throughput for large organizations, point to point links between sites, and providers that resell bandwidth. When a T3 is no longer enough, an OC3 is the next dedicated optical tier up.
How an OC3 connection works
An OC3 carries 155 Mbps of dedicated, symmetrical bandwidth over SONET fiber, the optical standard built for carrier networks. It can run over the provider's lit SONET ring or over dark fiber that you light yourself. An OC-3 supports dedicated internet access, private point to point links between locations, and wholesale bandwidth that providers resell.
Typical OC3 pricing
When it fits
✓ Great fit
Large enterprises, data centers, and campuses that need dedicated, symmetrical 155 Mbps with a hard SLA, organizations linking sites over private point to point optical circuits, and providers reselling wholesale bandwidth. An OC3 is a strong fit where SONET fiber or dark fiber is available and where guaranteed enterprise-grade throughput matters.
● Consider instead
If your sites can get modern business Ethernet over fiber, it often delivers comparable or greater bandwidth at a lower cost per Mbps than legacy SONET. An OC3 connection makes the most sense when you specifically need SONET, dark fiber, or a long-established optical circuit with a carrier-grade SLA.
How it compares
An OC3 delivers 155 Mbps, roughly 3.4 times the 45 Mbps of a T3 / DS3, and runs over SONET fiber rather than coax.
An OC12 steps up to 622 Mbps, four times an OC3, for the largest enterprise and carrier backbone demand.
Dedicated internet names the service; an OC-3 is one optical, SLA-backed way to deliver it over SONET.
What to look for
- ✓SONET or dark fiber. An OC3 can ride the provider's lit SONET ring or dark fiber you light; confirm which is available.
- ✓Point to point capable. An OC-3 can link two sites as a private optical circuit, not just provide internet access.
- ✓Reach and route. Optical pricing scales with distance and route; a longer OC3 span costs more.
- ✓SLA + restoration. SONET supports fast ring restoration; confirm the uptime and repair terms in writing.
Common questions
How fast is an OC3 connection?
An OC3 delivers 155 Mbps of dedicated, symmetrical bandwidth, also written as OC-3, over SONET fiber.
What does OC3 stand for?
OC stands for Optical Carrier; OC3, or OC-3, is the 155 Mbps level in the SONET optical hierarchy.
Is an OC3 dedicated or shared?
Dedicated. The full 155 Mbps of an OC-3 is reserved for your organization and backed by an SLA.
Can an OC3 run over dark fiber?
Yes. An OC3 can ride a provider's lit SONET ring or dark fiber that you light with your own optics.
Can an OC3 be used point to point?
Yes. An OC-3 can connect two locations as a private, dedicated optical circuit between sites.
What is the difference between a T3 and an OC3?
A T3 / DS3 is 45 Mbps over coax or fiber; an OC3 steps up to 155 Mbps over SONET fiber, the next dedicated tier.
What is the next step up from an OC3?
An OC12, which delivers 622 Mbps over SONET, is the next optical tier above an OC-3.
More on OC3 Connection
An OC3 connection, also written OC-3, is an enterprise-grade optical circuit that delivers 155 Mbps of dedicated, symmetrical bandwidth over SONET fiber. OC stands for Optical Carrier, and OC3 is the 155 Mbps level in the SONET hierarchy, built originally for carrier backbones. Because the circuit is dedicated and never shared, an OC-3 provides consistent throughput, low latency, and a carrier-grade service-level agreement. That makes an OC3 well suited to large enterprises, data centers, private point to point links, and providers reselling wholesale bandwidth.
An OC3 can ride the provider's lit SONET ring or run over dark fiber that you light with your own optics. The same circuit supports dedicated internet access and private site-to-site connections between locations. When 155 Mbps is no longer enough, an OC12 steps the optical model up to 622 Mbps; below it, a T3 / DS3 covers the 45 Mbps tier.
Types of serviceOptions and variants
What businesses use it for
- ✓Enterprise dedicated internet. An OC-3 delivers 155 Mbps of dedicated, symmetrical internet access with a carrier-grade SLA.
- ✓Point to point site links. An OC3 connects two locations as a private optical circuit that never touches the public internet.
- ✓Data center connectivity. The dedicated 155 Mbps of an OC-3 carries high-volume traffic to and from data centers.
- ✓Bandwidth resale. Providers resell portions of a dedicated, SLA-backed OC3 to downstream wholesale customers.
- ✓Campus and backbone aggregation. An OC3 aggregates traffic from multiple buildings across a campus over SONET fiber.
OC3 Connection details
An OC3 is a 155 mbps fiber or dark fiber line for enterprise applications. An OC3 connection can also be used for point to point access and is a viable solution for companies looking to resell bandwidth. Depending on location and OC3 provider availability, your full OC3 service will normally be priced between $15,000 and $100,000 monthly.
The connectivity ladderHow it compares, and where to go next
Where this connection sits among the options, with the businesses each one fits.
| Service | Connection details |
|---|---|
| Business DSL | 256 kbps to 1.5 mbps connection - Shared line for 5 to 50 users. |
| Fractional T1 Line | 256 kbps to 768 kbps connection - Dedicated line for 5 to 20 users. |
| Integrated T1 Line | 128 kbps to 1.5 mbps connection - Dedicated line for 5 to 30 users plus voice lines. |
| Full DS1 / T1 Connection | 1.5 mbps connection - Dedicated line for 20 to 50 users. A T1 connection can also be used for point to point access. |
| Multiple T1 Lines | 1.5 to 6 mbps connection - Dedicated lines for 50+ users and/or high bandwidth applications. Multiple T1 lines can also be used for point to point access. |
| DS3 / T3 Connection | 45 mbps connection - Dedicated line for 100+ users and/or high bandwidth applications. A DS3 / T3 connection can also be used for point to point access. |
| OC3 Connection | 155 mbps connection - Fiber or dark fiber line for enterprise applications. An OC3 connection can also be used for point to point access. |
| OC12 Connection | 620 mbps connection - Fiber or dark fiber line for enterprise applications. An OC12 connection can also be used for point to point access. |
| VPN Solution | Managed hardware VPN solutions for secure private network connections and VPN server software for secure virtual private networks. |