How to Optimize the Speed of a Local-Area Network

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This tutorial begins a multi-part, multi-week review of a new Synology workgroup server, the DS 1522+.

Part 1: How to optimize the speed of a network
Part 2: Choose and setup server hardware
Part 3: Configure server software and performance tests

When we think of a network, we first think about the server, which is at the heart of any network. However, just like the heart in our body, the server can’t do its work in isolation, it needs a “network” of gear to move data from central storage to the individual computer.

This gear includes:

One or more servers and their hardware components
How the server connects to the network
The network switch
Network cabling
Wireless access points
Individual Ethernet connections on each computer

NOTE: Larger networks often feature FibreChannel connections with more sophisticated data transport hardware and highly complex switches. For the purpose of this series of articles, I’m ignoring those networks because they require dedicated IT specialists for installation and support. These articles have a focus on Ethernet.

In general, a network is only as fast as it’s slowest component. So, if you are looking for ways to speed data access, it’s important to look at the entire network. It may be that simply replacing a wireless access point – or adding additional access points – relieves the slowdown. Or maybe you need a switch with a faster connection to the server. You won’t know until you look.

It also important to get help installing or upgrading a network from IT specialists. While you can do this yourself, and save money, competent professional advice can save time and reduce stress.

THE NETWORK SWITCH

The switch is that pizza-sized box with all the blinking lights. It connects all the devices on your network – computers, servers, wireless access points, printers – and shuffles data between them.

Generally, all ports (connections) on a switch run at the same speed:

Speed
Max. Data rate
Notes

10 Mbps
~1 MB/s
Very old, very slow

100 Mbps
~12.5 MB/s

1000 Mbps (1Gbps)
125 MB/s
The current standard

10 Gbps
1.25 GB/s

NOTE: Capitalization matters.

Mbps (also Mb/s): Megabits per second, the measure of data speeds
MBps (also MB/s): MegaBytes per second (Mbps/8)
Gbps (also Gb/s): Gigabits per second
GBps (also GB/s): GigaBytes per second (Gbps/8)

When a port (a single plug-in connection on a switch) is running at full speed, it is called “fully saturated.” For example, let’s assume that the server connects to the switch at 1G (1000 Mb/s) speed.

If one computer connects to the switch also at 1G, the data rate from server to computer will max out at 1G (about 125 MB/s).
If two computers connect to the switch, each at 1G, the data from the server is shared between them. So each computer gets 50% of the server, or 500 Mb/s (about 62 MB/s). The speed is limited (“gated”) by the speed of the server’s connection.
If four computers connect to the switch each at 1G, the data from the server is shared between them. So each computer gets 25% of the server, or 250 Mb/s (about 30 MB/s).
If eight computers connect to the switch, each at 1G, the data from the server is shared between them. So each computers gets 12.5% of the server or 125 Mbps (about 15 MB/s).

As you can see, the more computers that transfer data to or from the server at the same time, the slower the overall data transfer rate will be.

In the real life of an office, computers are transferring small files (Word/Excel) at different times, so that the server seems fairly peppy. However, when editing media, each computer is constantly transferring massive files, which means that the server connection is fully saturated all the time with data rates split between multiple computers.

To fix this, some switches support faster connections between the switch and the server. This could be:

Link aggregation. This combines multiple switch ports into a single high-speed port.
A 10G port on the switch that provides 10X faster speed between the switch and the server.

So, if you are constantly running into bottlenecks on your network, a good place to look is the switch. Is it fast enough to support the number of users on your network?

CABLING

The wires running between the switch and computer are easy to overlook because they are hidden in the walls. If your building was cabled a while ago, your cabling may not be fast enough to support the data you want it to carry.

The results are lost packets (the chunks of data carried by an Ethernet network), resulting in sending the same data over and over until it is received safely.

Cables are rated in Categories, where each category defines the speed of data it can carry and over what distance.

Category
Introduced
Max. Data Speed
MB/second
Notes

1
1980’s
1 Mbps
0.125 MB/s

3
Early 1990’s
10 Mbps
1.125 MB/s

5
1995
100 Mbps
12.5 MB/s
Limited to 300 feet

5e
Late 1990’s
1 Gbps
125 MB/s

6
Early 2000’s
10 Gbps
1.25 GB/s
Limited to 150 feet

6a
Mid 2000’s
10 Gbps
1.25 GB/s
Limited to 300 feet

7
2010
10 Gbps
1.25 GB/s
Extends cable length

8
~2020
40 Gbps
5 GB/s
Limited to 165 feet

It may be that your network speed is affected by the cable installed in your walls.

WIRELESS ACCESS PORTS

Wireless speeds are defined by a mind-numbing collection of acronyms, none of which make intuitive – or even alphabetical – sense. There are more than 60 wireless standards, but not all apply to computers. If you have an older wireless transmitter, it is guaranteed that you are not transferring data as fast as you could be.

Wireless Protocol
Theoretical speed
Actual speed
MB/second

802.11a
54 Mbps
~20 Mbps
~2.5 MB/s

802.11b
11 Mbps
2-3 Mbps
0.3 MB/s

802.11g
54 Mbps
~20 Mbps
~2.5 MB/s

802.11n
600 Mbps
40-80 Mbps
~8 MB/s

802.11ac
1300 Mbps
100-200 Mbps
~20 MB/s

802.11ax
10 Gbps
~600 Mbps
~75 MB/s

Actual wireless speeds also vary by:

Distance
Interference
Number of users accessing the same port

COMPUTER CONNECTION

The speed of the network is also determined by the speed of the Ethernet connection on your computer. While it is often impossible to change the speed of the Ethernet port on a Mac, it is possible to add docks which connect to the computer via Thunderbolt or USB-C connections to provide a faster pipe back to the server.

Standard
Max. Speed

100 Mbps
12.5 MB/second

1000 Mbps (1G)
125 MB/second

2.5 G
~300 MB/second

5G
~600 MB/second

10G
1.2 GB/second

As with wireless connections, actual transfer speeds vary by:

The size of the file being transferred (large files transfer faster)
The number of users accessing the server at that instant
The speed of the server
Whether you are writing (faster) or reading (slower)

SUMMARY

As you can see, the speed of a local-area network is dependent upon a number of factors, some of which we have more control of than others.

Still, once you know what to look for, it often becomes easier to increase the speed of your network by replacing the slowest components first. Sometimes, that’s all it takes to make a big difference in productivity.

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