Industry standard bandwidth guarantee?

That *is* a silly example.

A more proper analogy would be that you buy 12 gallons of gas, but the
station only deposits 11 gallons in your tank because the pumps are operated by gasoline engines and they feel it is fine to count the number of gallons pulled out of their tank instead of the amount given to the customer.

So if you tell a customer you are giving them 10 g of space for their email, you shouldn't charge them for the storage taken up by each individual email's headers. Is that how it works though? Not so much I think. As long as the pricing policy is consistent across the industry, and it is, then you are not being ripped off. Creating, implementing and maintaining a deep dive billing systems to figure out how much of your traffic is packet header and protocol and how much is your data would just add to operating expense which would eventually be passed on to the customer.

If you want a pipe that will let you transmit 10G of raw data, I can have than implemented. Just tell me where to connect the two ends. If you want to connect one end to our router or switch, we'll do that too, but it won't get you much. If you want to participate on the internet with a 10Gig link, you are going to have to use protocols, and the data will have to be in layer 3 packets, and they can be any kind you choose. But you are originating the request packets and receiving the reply packets and those will include overhead. We just transport them to and from the internet.

In TCP protocol RxWinSize/RTT*8 is your theoretical protocol download limitation in bits per second. You will not exceed that unless you run multiple sessions, and even then it will always be less than link speed, which is your physical limit, how many bits you can receive in a second, protocol or otherwise.

If you're selling to end users, under promise and over deliver. Tell them
20Mbit but provision for 25. That way when they run their speedtest,
they're delighted that they're getting more, instead of being disappointed
and feeling screwed. In practice they will leave it idle most of the time
This isn't a technical problem, it's just a matter of setting expectations
and satisfying them. Some of the customers might be completely clueless,
but if your goal is to make them happy, then explaining protocol overhead is
probably not the right way.


I have a feeling this issue only occurs with residential customers, and
perhaps small businesses. It is most likely cheaper to over deliver in this
case then to maintain a larger call center and support team to attempt to
explain end users how TCP has limitations. No two large communication
businesses (ISP in this case) with properly educated technical people (i.e.
network engineers or similar) on both ends should start an argument on who
gets to cover transmission overhead (or for simplicity, the packaging on
the cake).

We get this with wireless carriers -- they ask for quote for a 100 Mbps
Ethernet circuit, and then tell us afterwards that it's 100 Mbps of goodput,
so we have to size it to 125 Mbps to cover all their one MPLS and two 802.1Q
tags and to past the RFC 2544 test at 64-byte frames.


+1 on this exactly what we do, keeps the calls down.

Carlos Alcantar
Race Communications / Race Team Member
1325 Howard Ave. #604, Burlingame, CA. 94010
Phone: +1 415 376 3314 / /

Consider a better analogy from the provider side: A customer bakes a
nice beautiful fruit cake for their Aunt Eddie in wilds of
Saskatchewan. The cake is 10 kg - but they want to make sure it gets
to Eddie properly, so they wrap it in foil, then bubble wrap, then put
it in a box. They have this 10kg cake and 1kg of packaging to get it to
up north. They then go to the ISP store to get it delivered - and are
surprised, that to get it there, they have to pay to ship 11kg. But the
cake is only 10kg! If they pay to ship 11kg for a 10kg cake, obviously
the ISP is trying to screw them. The ISP should deliver the 10kg cake at
the 10kg rate and eat the cost of the rest - no matter how many kg the
packaging is or how much space they actually have on the delivery truck.

And then the customer goes to the Internet to decry the nerve of the ISP
for not explaining the concept of "packaging" up front and in big
letters. "Why they should tell you - to ship 10kg, buy 11kg up front!
Or better yet, they shouldn't calculate the box when weighing for
shipping! I should pay for the contents and the wrapping, no matter how
much it is, shouldn't even be considered! It's plain robbery. Harrumph".

Perhaps that's because in the case of shipping, it is usual and
customary to expect an item to be packaged carefully and that the
packaging is counted as part of the shipped package.

From the provider side (bearing in mind I've been in that business

for a few decades), usually what the customer wants is to understand
what they're purchasing, and if you as a provider tell them that
they're buying a 100Mbps circuit, they kinda expect that they can
shovel 100Mbps down that circuit. No amount of "but you should
expect that there's packaging and you should just /knoooooow/ (whine
added for emphasis) that means only 80Mbps usable" is really going
to change that.

That's why I designed an analogy that is much more representative of
reality than yours.

... JG