Mbps VS. Ping, which one is more important? advice needed!!!

Bernard111 · Aug 20, 2007

Quote from JackR:

Bernard:

Think of the internet as a series of different streets connecting two points. If all the traffic lights are green you get there at the speed limit. If there is an intersection that has a light that goes from green to red and back to green traffic slows. You get there, but more slowly. When a bad packet is detected it gets discarded (packets are internally serial numbered) and the router that detected the bad packet requests a retransmission of that packet from the preceding router. When it gets it successfully it forwards it on and the entire message stream, made up of a number of packets, is reassembled. This takes time. TCP/IP was designed to be robust (it was actually designed to remain functional during a nuclear attack) and to get the message through. In a properly designed network your message can be rerouted half-way through and you'd be unaware of a network problem unless you were measuring latency (or listening to music or voice).

What I did not mention in my previous reply is the influence of local loading on latency. To simplify a bit - Your PC connects to a router. That physical connection uses the ethernet protocol. If you have a number of PC's operating on your local area network the traffic will slow as there is contention for use of the network bandwidth. In a DSL connection you are essentially tied directly to your ISP's router and then into the backbone network, no local contention. In a cable connection you are tied into a neighborhood local area network. That network is tied to the ISP router. So as more of your neighbors use their internet connections your effective bandwidth goes down and your latency goes up. I haven't done any reading on the newer digital cable systems so it's possible they have changed their network architecture and this is no longer a problem.

Jack
More...

I'm talking about a DSL line, so there should not be 'contention'.

Thanks for your detailed reply, but about the packet Loss % that sometimes we read on tracert , what do you mean about these explanations that essentially say -no problem if it happens in an intermediate hop-?!

http://www.nessoft.com/kb/5
http://www.nessoft.com/kb/2
and here:
http://www.nessoft.com/kb/24

kiwi_trader · Aug 20, 2007

I'd suggest that 100% on intermediate nodes is no problem (because the router simply isn't responding) but less than 100% does introduce the potential for retransmission delays (ie packets being resent = have to wait around while the last one times out as not received and is resent).

I don't like to see losses.

JackR · Aug 20, 2007

Quote from Bernard111:

.....what do you mean about these explanations that essentially say -no problem if it happens in an intermediate hop-?!

More...

"Essentially say" is correct. It is the way they are written - If you read them carefully you'll see they do not say there is no increase in latency, just that the link is good for your purposes. This is from \42 (not on your list):
Anything less than this is showing a possible problem, but one that is probably not impacting your experience significantly at present (unless you're an online gamer or something similar that requires "twitch" reflexes).

Any packet loss along the way (unless the server has its ping response shut off) will affect your latency. Nessoft is saying that if you have no loss at the far end your link is working well enough.

Remember that once a packet is detected as bad it must be requested again from the uplink router. This increases latency. Bear in mind that the backbone links are not running at our slow 1.5 mbps, they are running in the gigabit/terabit range. Therefore, their retransmission time is very small compared to the time it takes to retransmit at our end and probably the vendor end.

Jack

Log in or Sign up

Mbps VS. Ping, which one is more important? advice needed!!!

which one should i use?

CABLE

ADSL

Bernard111

kiwi_trader

JackR