Data center infrastructure cabling skills

When you step into most data centers, administrators often first apologize for messy cabling. Wiring is simple-connecting servers to network switches with cables. However, cable placement like "noodles" affects the cabinet space utilization and appearance. chaotic scenes are like the tangle of many snakes, which cannot be clarified. We understand how things have evolved so far, but we cannot determine the root cause of this result. Is such chaos the result of technological evolution? More importantly, how can we improve data center cabling?

This article explains how to design and implement the data center cabling infrastructure from three major challenges: topology, quantity, and cable type.

Data center Topology

Data center cabling is different from traditional building cabling. The cable length is shorter and the performance requirement is higher. Different from the common office with only two to four terminals, a single cabinet may require 24, 48, 96, or more network cables or optical fiber connections.

Three basic methods for data center cabling:

1. Point-to-Point

2. convergence at the end of a line

3. Cabinet top aggregation (using fiber optics or switches)

First, we will introduce point-to-point cabling. This is the cabling method used by the data center over the years, as we have seen before-a mess. Point-to-point means to pull the network cable under the floor, in the air (whether or not there is a cable trough) or through the server Cabinet as long as necessary. Cables are usually made on the spot or directly used with existing links. The old cables are usually not removed or marked, which makes tracing and searching more difficult. As a result, data center personnel need to maintain the cables in a "rat's nest" environment. Servers and jumpers can disrupt the distribution of cables. When high-density network switches are installed in cabinets or other places, the form is more severe. In short, the point-to-point mode is no longer able to serve the data center well.

End-to-End aggregation Architecture

Convergence at the end of the line, also known as "regional convergence", is a common cabling method for data centers in recent years. In the line-end wiring architecture, there is a place specifically used to place the distribution frame and convergence switch, usually located at the end of the same line of the cabinet-sometimes in the middle-to facilitate connection to the entire group of server cabinets. The distribution frame is installed in each slot, and permanent cables are connected to the corresponding aggregation cabinet through these racks. Other cables are usually optical fiber cables used to connect convergence layer devices to the core network, a. k. a main distributed framework or area. It can be considered as a compressed version of the standard "star topology" in the data center. A server cabinet is like an office, while a converged cabinet is an intermediate distribution frame (IDF) or a communication room (TR ).

The line-end aggregation simplifies the difficulty of adding hardware. You only need to connect the server to the required distribution frame, and then connect the distribution frame to the corresponding aggregation layer switch. Two short jumpers are required for each connection, which is also conducive to future installation and maintenance.

Similarly, the access layer switch connects to the core network through optical fiber cables, so the entire installation process only involves simple jumpers. The "end-of-line" aggregation minimizes the length of the required jumper because all distribution frames have labels for easy tracking and the documents that record relevant information are easier to read. Not only that, because longer cables are no longer needed, there is no reason to keep old, lengthy, and low-performance cables. This avoids system performance degradation due to patch cord compatibility issues.

Cabinet top aggregation Architecture

The Cabinet top aggregation is the latest wiring method, but it can be seen as a variant of the row and tail convergence. The Cabinet top aggregation depends on the server configuration density. We will discuss how to select the corresponding Wiring Scheme for the data center wiring architecture. If a cabinet is filled with servers, the preferred solution is to install access layer switches on each cabinet. If the server has dual NICs and has Fault Tolerance requirements, you can consider installing one more switch. Generally, a low-level switch is installed for system management. All switches are connected to the core network through optical fiber jumpers, which is similar to line-tail aggregation. So the effect of Cabinet top aggregation is the same as that of Row-tail convergence, but it is more conducive to expansion-you can install cheap switches on each cabinet as needed, and you can complete the migration through reconfiguration. The failure of a single switch has much less impact than that of a large switch located at the end of the line.

When you need a blade server that uses a vswitch of a specific type, the Cabinet top aggregation is your best choice. In this case, we only need to connect the optical fiber to the core network. Therefore, as long as each cabinet has the same Optical Fiber Device, network convergence can be realized. Sometimes you may even encounter mixed installation, but the overall structure is not affected, so you only need to connect different blade machines to different switches. In general, common optical fiber devices can meet the needs of high-performance applications.

Select the most suitable data center cabling Architecture

How to choose the end of a row or the top of the Cabinet to converge depends on the device density, application throughput requirements, and hardware connection details. In a large data center, the two design methods can be used in different areas of the application to give full play to their respective strengths. In short, the answer is not the only one. The general trend is to focus on fiber-optic applications, and the choice of cabling architecture is based on "customized on demand". This is the key to all businesses.

The storage network has been connected through fiber channels for many years and adopts the Cabinet top aggregation structure. In the storage area network (SAN), the optical fiber jumper connects the distribution frame with the storage connection switch. However, this requires an additional network for each cabinet-this solution is not very cost-effective.

The latest trend is Ethernet Fiber Channel (FCoE), which enables SAN connections to use the same topology and use fiber paths as transmission networks. FCoE reduces physical line requirements, increases bandwidth, aggregates networks, and integrates SAN management. Currently, FCoE is still in its initial stage. Not all vendors are compatible with this mode. In addition, how to connect to storage depends on the network connection requirements of hardware and other factors based on the network cable function. Even so, FCoE may become a general standard supported by manufacturers in the near future.