on 07 December 18
When it comes to server connecting in data center, network switch is a vital part. You may heard about it that top-of-rack switch is very popular to support power required for large installations and the ToR design is very convenient for servers to connect. However, what is top-of-rack switch and how to buy it when needing? Let’s find out the answers together with the illustration below.
What Is Top-of-Rack Switch (ToR Switch)?
There is no precise saying about top-of-rack switch definition on wiki and other sites. But actually, top-of-rack switch is one kind of various switches located or installed inside a rack. In the top-of-rack design, servers connect to one Ethernet switch or two (for example, gigabit Ethernet switch or 10GbE switch) installed inside the rack. The top-of-rack switch is usually placed at the top of the server rack for easier accessibility and cleaner cable management, which is the coming of its name. However, ToR switch can be placed anywhere inside a rack and connected to aggregation switches via fiber optic cables.
Normally, the top-of-rack switch is fixed low-profile (1RU/2U) configuration. The key characteristic is that all the copper cabling is inside the rack and most of the cables connecting servers to the rack switch are short RJ45 patch cables. However, there are a few fiber cables used in the rack as well in order to link the rack to the data center network. Fiber cables to each rack provide much better flexibility and investment protection than copper cables because of the unique ability of carrying higher bandwidth signals with longer distances. Therefore, there is no need for a bulky and expensive infrastructure of copper cabling running between racks and throughout the data center.
Pros and Cons of Top-of-Rack Switch
- Minimizes the complexity of the cabling system because all the servers are connected to the switches inside the same rack.
- Reduces cable length to provide a clean and tidy cable management as each server does not need to connect to the aggregation switch by itself using a long cable.
- This ToR design can be upgraded to run network at higher level of 40GE or even 100GE in the future with minimum costs and changes to the existing cabling.
- Supports modular deployment of data-center racks as each rack can come in-built with all the necessary cabling or switches and can be deployed quickly on site.
- More top-of-rack switches are required in such installations along with higher maintenance costs.
- Causes waste due to unused ports in each rack because of fixed configurations on top-of-rack switches and different servers.
- Difficult to realize unplanned expansions within a rack.
How to Buy Top-of-Rack Switch
If you want to buy a top-of-rack switch, there are many considerations you need to take into. To begin with, a 1U/2U configuration is your priority. Then you need to consider the number of your port needs to avoid unnecessary waste. In addition to port numbers, you must determine whether you need a fiber switch of 10 Gbps, 40 Gbps, or even 100 Gbps for fiber interconnects. At last, evaluate a vendor's ability to support your top-of-rack switches in terms of hardware replacement, software upgrades and troubleshooting assistance.
Original source: http://www.fiberopticshare.com/top-of-rack-switch.html