Many networking technologies reside in the data center. In this video, you’ll learn about MDFs, IDFs, hot and cold aisles, cable infrastructure, and more.
A distribution frame is an area of the network where you are passively terminating cables. This usually involves punch down blocks, like the ones we see here. Could be patch panels or any other method where we are terminating those cables, usually in a data center or some other large facility.
You will usually find this distribution frame on the back wall of the data center, and it’s often terminating cables that are coming in for your local area network and voice communication. And although the punch down blocks and patch panels that we have on the wall are technically the distribution frame, we often refer to the entire room as the distribution frame room.
For example, the primary distribution frame is called the Main Distribution Frame or MDF, and we often refer to the entire room where it’s located as the MDF facility. The MDF is usually a single room. It’s often the data center or central point of the network. And this is where we might bring in wide area network connections and punch those down, along with all of our internal local area connections as well.
Since we have all of this connectivity in one place, it is a perfect testing point, especially if you need to test both your internal local networks and your external wide area network connections. And even if your network doesn’t have this large set of punch down blocks in the back, we sometimes even often refer to this central data center room as the MDF.
Here’s a view of one MDF. This one contains a number of different racks, with computer equipment and the networking components as well. Here’s another MDF. You can see a large number of punch down blocks or patch panels that are on the single rack and some on individual racks as well. And it’s intermixed with the equipment that we need to run inside of this data center.
Another type of distribution frame is the Intermediate Distribution Frame or the IDF. Usually the IDF is in a separate floor or a separate building, and it’s often directly connected to the MDF. Most IDFs these days include switches, routers, and other equipment that you need to be able to connect this area of the network to the larger MDF.
Usually find this combination of MDFs and IDFs in medium to larger scale environments, where you need to have many different remote rooms all connecting back to the central data center. Here’s a view of what that would look like, where you have the MDF. Maybe this is where our internet connection comes in.
There might be a core router and a core switch. You might even have file servers and database servers in the MDF. Maybe on different floors of the building, you would then have individual IDFs. In this case, there are two. But there might be more than that in this particular environment. And in the IDF, you might be connecting users on the floor to a central switch in the IDF. And that switch is connecting back to the main core switch in the MDF.
We’ve already seen an example of an IDF and an MDF. And one of the things that you’ll notice is there are racks that are very common in each of those environments. That’s because the racks that we use in these environments are standardized and most rack sizes are 19-inch racks. They’re 19 inches across in each of these.
And we design our equipment to fit perfectly into that 19-inch width. You’ll also notice that the equipment in these racks might also have different heights. And we have a standard for those heights known as a rack unit or a U. 1U would be 1.75 inches.
And we can measure a different number of units based on that value. So you can easily tell somebody that we need 2U or 3U of space to be able to install a piece of equipment. And most racks, like the ones we see here, are generally about 42U in height.
Although the width is standardized, the depth of these racks can often vary. There might be racks that are very shallow or others that might support a much longer piece of equipment that you would install. Fortunately, most devices follow the standardized form. We know that if we’re receiving a piece of equipment that is rack mountable, that it will most likely be 19 inches wide. We’ll just need to make sure that we have a rack that is deep enough to handle that particular piece of equipment.
Since we have these standard widths, we can start stacking this equipment and using every bit of real estate that we might have available. For example, this system administrator has installed a server that’s about 3U in height. And they’re installing another set just above it so that they can stack them one right on top of the other.
Now that we have all of this equipment in the data center and it’s all running constantly, it’s creating quite a bit of heat. We need to make sure that we have a way to cool this data center so that all of this equipment continues to work optimally. We would do this by implementing an H-V-A-C or HVAC system. This stands for Heating, Ventilating, and Air Conditioning.
This is very different than simply purchasing a window-mounted air conditioner and turning it on. There’s a lot of engineering that goes to designing and implementing an HVAC system in these large data centers. For example, we not only need to make sure that the HVAC can support the amount of heat that’s going to be created by these systems. We also need to make sure we have enough power to run the HVAC.
And we also need to make sure this is integrated into the fire system so that we’re able to turn this off automatically if a fire is detected. One thing that you’ll notice in a data center is that the different aisles of the data center may be designated as a hot aisle or a cold aisle. This hot and cold aisle is an important designation, especially as we’re installing new equipment into the data center.
We want to be sure that we’re installing the equipment in a way where the hot air is being blown into the hot aisle and it’s pulling in cold air from the cold aisle. Here’s a cross reference of a data center. On the left and right sides, we have our HVAC system. And in this particular environment, the cold air is going under the floor and the hot air is being pulled out of the ceiling.
The cycle starts with the HVAC creating the cold air and that cold air is going underneath the floor in this raised floor environment. There are vents and holes in the floor that will allow the cold air to flow into a cold aisle. This is often the front of the servers and the servers are pulling in that cold air to cool the inside of the server itself.
Once that air is heated up, it will be sent out the back of the server into a hot aisle. And that hot air is going to rise into the ceiling, where it will then be pulled back into the HVAC, re-cooled, and the entire system repeats again.
Here’s a data center where we can see both the hot aisles and the cold aisles. You’ll see the cold aisles are covered with this plastic to keep that cold air inside, and the hot aisles would be the ones on the outside without the plastic. You’ll also notice this is a bit different than the previous diagram, because there is a concrete floor, and there’s no way to have a raised floor in this environment.
So it looks like they’re blowing the cold air directly into the cold aisle from above, it’s being pulled through into a hot aisle, and then it goes back into the ceiling where the entire process repeats. When we install network cabling, one of our goals is to not move or touch that cabling again. We want to be sure that once it’s installed, we can trust that that cable will always be working optimally.
One of the things that we’ll commonly do is have all of the desks that are on a floor of a building all have single runs of wire all the way back to an IDF. Inside of the IDF closet, we’ll have a patch panel, and commonly we might have a patch panel with a 110 block where we will punch down those wires onto the back side of the patch panel. And on the other side of the patch panel will be the traditional RJ45 modular connectors.
This means that if we need to connect any user on the floor to any switch on our switches, all we have to do is run the appropriate cable from the RJ45 connector. We no longer have to touch any of the cable that’s running from the back of this patch panel to the end user’s desk. So we can begin installing all of the connections we need through these patch cables from the patch panel itself into the switch that we might be using.
This also allows us to address any type of moves, adds, or changes. If someone out on the floor moves to a different desk, we can simply move where their patch cable happens to be and plug them into a different connection. And of course, if we hire new employees and we want to make sure that they have the correct network connectivity, we don’t have to run additional cables, because we’ve already run those cables. All we have to do is add new connections from our patch panel to the appropriate switch connection.
Here’s what this patch panel looks like in our IDF. You can see on this side of the patch panel, we have the RJ45 connections. And we’re coming out of those RJ45 connections, and we’re plugging them into the switches that are directly underneath. This means we can keep all of those cables in place between the patch panel and the desk out on the floor. All we have to change are the internal connections inside of our IDF.
Here’s another view of a patch panel. This one is connecting from the patch panel directly to the switch that’s above it. And notice there are numbered connections on that patch panel so we know exactly which desk we’re connecting or disconnecting.
There are similar but slightly different configurations for fiber optics. This is a fiber optic distribution panel, where we’re bringing in fiber runs from another building or another floor, and we’re bringing all of those back to connections that we have access to on the distribution panel. One of the important characteristics when installing fiber optics is making sure that we don’t exceed the bend radius.
And you’ll notice in this distribution panel that we are looping together in a very large loop the fiber to make sure that we don’t break the fiber by bending it too far in the panel itself. And it looks like in this distribution panel, we have some additional fiber that is wrapped around. We refer to this as a service loop, so that if we need to move this distribution panel or add additional fiber, we can simply extend it with the fiber that’s already run. This gives us flexibility in the future to be able to make changes without having to rerun a very expensive fiber optic connection.
In some of the previous pictures of the data centers, you saw that some of the racks were open. But there were some racks that were completely closed that had locks on the front of the rack. This is not uncommon in any type of data center because it allows the system administrator a level of additional security and control over the components inside of the rack.
We’ll often install these racks side by side directly to each other to optimize the space that we have in the data center. And it’s not unusual to have a door on the front of the rack, where we can have a lock and a way to prevent others from gaining access to the equipment inside of the rack.
Here’s a good example of racks that are completely locked up. You can see in this case that we do have ventilation in the front. There’s often ventilation in the top and the bottom as well, so that the equipment inside is able to be cooled properly. Here’s a closer view of these racks. You can see that each of these racks has a handle with a lock on it. And you can see where you would add the key to be able to gain access to the equipment that’s on the inside.