What Is a Cross Connect? {Data Center Tech Explained}

October 20, 2022

Introduction

Choosing the right data center connectivity options is one of the main tasks of data center networking management. Connections between various locations in the facility require careful planning to minimize data transfer latency and avoid congestion.

This article focuses on a network connectivity type called cross connect. It provides an overview of the function and importance of cross connect in data center networking.

What is a cross connect? Data center tech explained.

What Is a Cross Connect?

The term cross connect represents the cabling necessary to establish a direct link between two separate hardware units in a data center. It allows the owners of the units to establish a private network link and eliminates the need to connect using the internet.

Collocation providers typically provide tenants only with a connection to the main distribution frame. This connection is established by linking the patch panel in the tenant's enclosure with another patch panel that mirrors the ports of the original panel. The second patch panel for each tenant sits in the Meet-Me Room (MMR).

If two tenants wish to establish a direct connection between their enclosures, they may ask the colocation owner to provide a cross-connect, i.e., to use a patch cable to connect their respective patch panels in the MMR.

Cross Connect vs. Interconnect

Cross connect is often confused with another data center connectivity type - interconnect. The following section explains both types and provides diagrams for a more apparent distinction.

An interconnect is cabling used to link active equipment with other data center hardware units. Copper trunk cabling connects the patch panel in a server cabinet with the distribution panel, which is usually located in the switch cabinet and connects directly to the switch. The diagram below illustrates this setup.

A diagram illustrating an interconnect.

The cross connect design comes in two basic types: the three-connector and the four-connector cross connect. Both types require more components than the interconnect model, introducing an additional layer of complexity.

The three-connector cross connect type retains the distribution panel used for interconnections, but also adds the equipment patch panel at the switch end. The equipment panel connects to the switch and mirrors the switch ports. The two patch panels are then linked using the cross connect cabling.

A diagram showing the three connector cross connect model.

The four-connector cross connect type introduces another patch panel to the setup. The two middle patch panels sit in a separate enclosure called the cross connect cabinet. One panel mirrors the ports of the panel in the server enclosure, while the other links to the equipment panel in the switch cabinet. The connections between cabinets are established using two permanent copper trunk cables.

The diagram below illustrates the connections between and within the three cabinets containing the four-connector cross connect type equipment.

A diagram showing the four connector cross connect model.

Why Are Cross Connects Important?

Cross connections offer performance improvements and convenience that traditional internet connections cannot match. They make a difference because:

  • They are less prone to network latency and bottlenecks, which makes them an excellent option for enterprises that require stable network connections with their partners.
  • Compared to traditional telecom network providers, they can prove to be a less costly solution for bandwidth-hungry projects.
  • They assist network admins in controlling and utilizing a wide variety of network assets.

Types of Cross Connects

The are many types of cross connects, offering different sizes, bandwidth, distance capabilities, connection quality, etc. The following is the list of the most common cross connect types:

  • SMF (Single-Mode Fiber) - A fiber optic cable that transports data through a single light ray.
  • MMF (Multi-Mode Fiber) - A fiber optic cable using LEDs to transfer data through multiple light rays.
  • CAT5 Ethernet - An ethernet cable with 100/10 Mbps bandwidth. The improved version of this cable, CAT5 Enhanced, offers 1Gbps bandwidth and has better signal interference protection.
  • CAT 6 Ethernet - A modern version of the CAT5 cable, offering 10 Gbps bandwidth for lengths of up to 164 feet (longer cables support the same 1 Gbps bandwidth as CAT5 Enhanced). CAT6 Augmented cable doubles the supported high bandwidth distance to 328 feet.
  • COAX - A durable and cheap cable that transmits electrical signals through an insulated copper wire.
  • Copper - A heavy-duty, cheap copper cable with low bandwidth.
  • POTS (Plain Old Telephone Service) - A cable using copper loops to transfer analog signals. This cable type also has limited bandwidth and features but tends to be very reliable.

Note: phoenixNAP's flagship data center facility offers AWS Direct Connect, enabling direct fiber connection to AWS through a physical uplink from Phoenix, AZ.

Cross Connect Benefits

Cross connections offer numerous advantages compared to standard ISP connections. From increased security and data loss protection to performance improvements, cross connects present the best connectivity solution for a wide range of use cases.

Improved Security

Every piece of data exchanged over the internet is susceptible to security risks common to all public networking solutions, such as cyber attacks and data loss. Cross connections enable communication via a private network, protecting data integrity, and significantly reducing the risk of a security breach.

Reduced Latency

Large data transfers over the internet tend to suffer from performance issues related to network latency. Cross connects provide low-latency private links between two endpoints in a network and help users avoid public network bandwidth congestion.

Reliability

Using cross connects simplifies the network topology and eliminates many potential points of failure commonly found in public networks. Therefore, cross connections are much more reliable for organizations that cannot afford server downtime.

Convenience

An opportunity to establish direct connections to various carriers and internet service providers at the same place where you keep your servers is an added benefit of a tenancy in a reputable data center. Cross connects are a convenient and hassle-free way to improve the quality of your service.

Conclusion

This article provided an overview of cross connect, an important data center connectivity type. It explained the function of cross connects in a data center and presented their most important benefits.

If you participate in a project that requires data center services, read Data Center Selection: Key Requirements of a Data Center. For valuable tips relating to migration to a data center, refer to 11 Data Center Migration Best Practices.

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Marko Aleksic
Marko Aleksić is a Technical Writer at phoenixNAP. His innate curiosity regarding all things IT, combined with over a decade long background in writing, teaching and working in IT-related fields, led him to technical writing, where he has an opportunity to employ his skills and make technology less daunting to everyone.
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