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novice ping statistics question

marcusbrutus
Level 1
Level 1

Hi. I was just wondering about the ping statistics. Supposing I have a 1mb fractional t1 connection, from a theoretical point of view, i should be able to transmit 125KB of data per second from my WAN port to my provider's port or an a one way delay, if i transmit 32 bytes, of 0.256ms granting that my workstation is the only pc accessing the internet. But when i do a ping to let's say www.yahoo.com, i would get a round trip time of around 200ms which would be equivalent to 150ms one way delay. Dividing 32 bytes by this 200ms would result in 160 bytes per second. I am sorry but i am extremely confused. I understand that there are latencies involved from my provider's routing device to yahoo's server but computing the delay from that premise would yield a 200ms - 0.256ms = 199.744ms delay. It just seems to me that even if i reduce my bandwidth by ten it would hardly affect the overall delay.

Thank you in advance to anyone who can clarify this for me.

2 Replies 2

Joseph W. Doherty
Hall of Fame
Hall of Fame

There's more involved then just your nomimal local bandwidth. Often on a WAN, distance based latency is an important component.

Here's a tool you might experiment with to see what might contribute to latency, http://www.netqos.com/resourceroom/calculator/

One important thing to remember is the difference between bandwidth and the physical interface speed. It's possible to have 512 kb/sec of bandwidth on a link that is 10 Mb/sec.

Router processing times, server processing times, link speeds, and physical propagation delays take effect. Depending on the load of the server or interface, there may be software buffers waiting to fulfill your request based on other traffic.

hth,

nick

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