We help IT Professionals succeed at work.

# Bandwidth versus Throughput

on
Naive Question on the Bandwidth versus Throughput

EE Members / Gurus ,

Need your help to clarify the definition

1. If i hear in a meeting , client has internet link of 40Mb . Does this means his bandwidth is 40Mb or the throughput ?

2. What does the terminology means ' ' pipe can handle 80Gb of traffic ' . Does this mean the backbone / backplane speed can or should handle this traffic

Regards,
Sid
Comment
Watch Question

## View Solutions Only

Software Engineer
Distinguished Expert 2019
Commented:
Throughput  = speed effectively used.
Bandwidth = the highest throughput one can send across a line.

40Mb is 40 Mega bit (there is no time specified here..., so it is just size), no indication of speed.
Now this is not the custom spec for a line, which specified the capacity in bits per second (Mbps) .  Which would mean a upper bound of the throughput, aka bandwidth maximum.
Also it should be expected that this would be a line with 40Mbps symmetric speed, unless otherwise advertised.

80Gb mean 80 Giga bit = Capacity. No time involved again.  so it should be assumed to be throughput/ capacity without time.  = After 80Gb or 10GB the line breaks down?... and a new one is needed.

At least parts of the units are missing.
Sr. Network Engineer
Commented:
This question is a little oblique with a lot of what if.  Please note that answer is going to come with a fair bit of assumption to accommodate.  Lets take it one question at a time.

1. If i hear in a meeting , client has internet link of 40Mb . Does this means his bandwidth is 40Mb or the throughput ?

If we get right down to the hardline definitions then your 40m circuit would be the available bandwidth and specific to the capabilities of the circuit itself.  Your actual throughput will be an aggregate function of the circuit and all equipment, hosts, etc. participating in the communication with the primary determining factor being the lowest capability involved in the transaction.  Ex.  If you have a Gig WAN circuit but only running 100M LAN then you will never see anything higher than about 90/95M due to the capabilities/limitations of the LAN connection.

2. What does the terminology means ' ' pipe can handle 80Gb of traffic ' . Does this mean the backbone / backplane speed can or should handle this traffic
My gut would be that they are telling you that the circuit will handle the projected load over interval.  In other words, you have an expected load of 80G and an expected transfer interval of X-Minutes/Hours/Etc.  The 40M circuit is expected to handle that load within the desired interval.  Actual throughput (again) is going to be an aggregate function pinned to the least common denominator but the circuit function in regards to the load is a direct relationship.
Most Valuable Expert 2012
Expert of the Year 2018
Commented:
I agree with the above.  Throughput is normally 1 Gbit/sec or less.  My routers are 900 Mbits/sec.  Some time back I had to upgrade my router to achieve the speed provided by the ISP.

So Throughput is a critical measurement to the speed you get.
Fractional CTO
Distinguished Expert 2019
Commented:
As noci said...

Bandwidth - theoretical fastest speed possible.

Throughput - real speed, based on all manner of factors.

Generally throughput is what matters.

1. If i hear in a meeting , client has internet link of 40Mb . Does this means his bandwidth is 40Mb or the throughput ?

This is theoretical fastest speed. Depending on technology used + ISP, this number may be near meaningless.

For example, a symmetric (1G up + 1G down) Google fiber line will run close to 1G up + down all the time.

A Spectrum cable line of 500/50 can run near zero much of the time, because their tech is just so bad.

The only way to know for sure what's really occurring on your line is to test your line periodically.

https://SpeedTest.net provides a good speed test tool.

2. What does the terminology means ' ' pipe can handle 80Gb of traffic ' . Does this mean the backbone / backplane speed can or should handle this traffic.

This means what it means. The pipe can handle 80G of sustained traffic.

Tip: If anyone tries to sell you a connection like this, they're likely lying about speed.

https://searchnetworking.techtarget.com/definition/Optical-Carrier-levels-OCx provides an overview of backbone throughput levels.

So to get 80G sustained throughput, you'd require bonding 8x OC-192 (10G) pipes together or 2x OC-768 (40G) pipes together.

I've never heard of bonding routers which can handle an 80G pipe. In fact, there's no generally used terminology to even represent an 80G pipe.

Likely someone is spinning a tall marketing tale getting you to buy something crazy, they can't really deliver.
Fractional CTO
Distinguished Expert 2019

Commented:
Tip: For more detail about large pipes, call a company like Pair or OVH + talk with a human in their customer support.
Sr. Network Engineer
Commented:
Delivery of 80G of traffic over a circuit is far from a pipedream.  I would agree that if someone walked in and said they could provide WAN speeds of 80G I would have to question that and most likely snort my coffee through my nose.  That said, if the claim is that a 40M circuit will handle 80G of traffic, there is no reason to dismiss that claim out of hand as a falsehood or deception and to jump to that claim is hasty at best.
Fractional CTO
Distinguished Expert 2019
Commented:
De
livery of 80G of traffic over a circuit is far from a pipedream.  I would agree that if someone walked in and said they could provide WAN speeds of 80G I would have to question that and most likely snort my coffee through my nose.  That said, if the claim is that a 40M circuit will handle 80G of traffic, there is no reason to dismiss that claim out of hand as a falsehood or deception and to jump to that claim is hasty at best.

My use of the term pipe dream is same as you snorting coffee through your nose.

If a guy in a suit showed up at my door today + said, "Have I got a deal for you today on an 80G pipe"... I'd likely pass out with laughter... unless... I was drinking at the time... then... I'd snort my drink through my nose.

Commented:
One other item to consider which happened here where I work; we have something like 125 Mb download but our external firewall port is 100 ... so we won't benefit from the extra until we physically upgrade the firewall to one with a gig port ...
Software Engineer
Distinguished Expert 2019

Commented:
Only 125Mb download, do you need to get a new cable when there 125Mbits have passed?...
125Mbps is a measure of speed.(amount over time).

125Mb is 125 Mega bits, roughly 12.5 Mega bytes,... or just a very old USB stick of amount of data, no indication of speed.
Obviouly you need to refresh the firewall more often as then is full after 100Mb...

Commented:
Oops, I may have written it wrong (above) but bottom line is ... our external port won't even support what we are paying for.
Software Engineer
Distinguished Expert 2019

Commented:
Getting units, & scales right is rather important. Esp if they are the ones that get discussed.
And you are right about the mismatch in capacity.  The smallest bandwith limits the overall theoretical maximal throughput.
(in practice it will get lower still due to overhead in processing on the firewall.).

Commented:
Thanks Team for your valuable inputs .

BTW , 80GB it was not a conversation , it was just an example :)

In short ,

Bandwidth is theoretical speed
Throughput is actual speeed ( which can be audited by using tools likes speed test ) , right .

Sid
Distinguished Expert 2019
Commented:
There is a huge difference between GB and Gb and for networking it is usually a per second timeframe. And for networking the ISP's usually use the Gb (gigabit) vs GB (gigabyte) numbers. For instance I have 1Gb/s down/300Mb/s up this gives me a total bandwidth of 1.3GB/sec
Hard Drives/Memory is usually measured in bytes not bits.
Sr. Network Engineer
Commented:
More accurately, and what I was attempting to get at earlier is:

Bandwidth is the available capacity of a given segment of a network path.

Throughput is the measured transfer rate over a network path end to end.
Top Expert 2014
Commented:
Just to add a little bit more.   Throughput typically relates to how fast you can transfer data. in a single stream.  Bandwidth is the total amount of "speed".  I most cases these two are relative close.  Meaning, if you have a 1Gbps link your "bandwidth" is 1Gbps and you can get close to 1Gbps in a single stream.

Now, if you have multiple links, say you have 2 1Gbps links.  Your bandwidth is now 2Gbps, but your throughput (single stream) may still be limited to 1 Gbps because normally traffic on a single stream will only use one link.  The difference is with 2 links I can have 2 streams both getting about 1Gbps or close to 2Gbps of traffic, but my throughput is still only 1Gbps.

Think of like a highway where the speed limit is 55.  It does not matter how may lanes I have, a single car is still limited to 55, but the more lanes the more cars, the more cars, the more people can get from point A to point B.