Computer networking is a crucial for data-sharing, communication and resource management in the IT infrastructure of any company. Low bandwidth (or "bottlenecks") in any part of the network will slow down network activity and decrease productivity. With the growing number of people having internet access at home, setting up home offices and using high bandwidth applications such as video,, network performance is increasingly becoming an important factor to the home users too.
Network bandwidth is measured in bits per second:
1 Kbits/sec = 1024 bits/sec
1 Mbits/sec = 1024 Kbits/sec = 1,048,576 bits/sec
The main options for the home user to connect to the Internet are by using analogue dial-up modems, DSL (Digital Subscriber Line) modems over telephone line, cable modems over cable television network or wireless. Dial-up connections can support up to 56Kb/s but typically average between 30Kb/s - 40 Kb/s download depending on your connection. ADSL is typically capped at 256Kb/s, 512Kb/s, 1000Kb/s or 1500Kb/s depending on your Internet service provider and your DSL modem. However, recent advances in ADSL technology can provide bandwidth of up to 24Mb/s (for ADSL2+). Cable broadband is typically 'uncapped' depending on your Internet service provider. New DSL technology such as VDSL (Very-high-bit-rate DSL) offers up to 54 Mb/s download bandwidth but very few Internet Service Providers offer such service.
If the budget supports it, cable is recommended. However, ADSL2 is also capable of producing good bandwidth without the need to bundle cable broadband with cable television subscribtion.
The table below displays some of the theoretical bandwidth of the different technologies:
|Connection type||Theoretical Bandwidth*||Typical service|
|Mobile Internet (WiMAX - 802.16e)||up to 70 Mb/s (short range)||< 1Mb/s|
|Cable||up to 30 Mb/s||3 Mb/s|
|Wireless (802.11g)||up to 54 Mb/s||6.0 (wireless to wireless)
13.5 (wireless to UTP)
|ADSL2||up to 24 Mb/s||12 Mb/s|
|Wireless (802.11b)||up to 11 Mb/s||1.5 (wireless to wireless)
3.7 (wireless to UTP)
|ADSL||up to 8 Mb/s||1Mb/s|
|56K dial-up||up to 56 Kb/s||56 Kb/s|
* All bandwidths mentioned are for downstream traffic
There are 3 basic speeds available for fixed wired data networks in the home, 10Mb/s, 100Mb/s and 1000Mb/s (Maximum speeds). Network adapter cards that support all 3 speeds are currently the most popular. Our experience is that you would typically achieve in the low 90's with a basic PC and a 100Mb/s card. A Gigabit card sounds much faster at 1000Mb/s, however a typical upgrade to Gigabit network using an existing PC, is via a Network Card that connects to the PCI bus in your PC. The PCI bus limits the bandwidth achievable with a gigabit network; from our testing average throughput is in the low 300Mb/s. The speed of the CPU (Central Processing Unit) will also impact the bandwidth achieved with a Gigabit Network . For the home user, it probably makes sense to upgrade to a Gigabit network at the same time you next update your PC, by ensuring that the Motherboard supports Gigabit Network ports.
Wireless networking is also becoming increasingly popular. Users typically sacrifice bandwidth for "neatness" and portability - there is no need for wires stretching over distances. The 2 common types of wireless network protocol, 802.11b and 802.11g, with a maximum speed of 11Mb/s and 54Mb/s respectively. However, in normal use, the bandwidth is much lower. You can find PassMark's Wireless Bandwidth Testing page here.
Refer to the table below for some average data networking bandwidth:
|Connection type||Theoretical bandwidth (Mb/s)||Average bandwidth (Mb/s)|
|Fibre-optic||up to few hundred Gb/s||N.A.|
|802.11b wireless||11||1.5 (wireless to wireless)
3.7 (wireless to UTP)
|802.11g wireless||54||6.0 (wireless to wireless)
13.5 (wireless to UTP)
|1000Base-T (Gigabit) UTP||1000||300|
Testing your network bandwidth
PassMark's Performance Test advanced network feature allows you to easily test and check the rate of data transfer between 2 networked computers. The graph below is produced by Performance Test when running the advanced network test (using variable block size) between 2 computers (both with 100Base-T network card) networked with a D-Link 100Base-T switch:
From the above result, the achieved bandwidth is only half (at around 49 Mb/s) that of the maximum bandwidth.