Solved: IPLC Link Latency

chrislau388 · ‎11-10-2008

Hello,

I have 1 STM1 and 1 STM4 IPLC links to my Data center in the UK. However, both IPLC links have about the same link response time that is approximately 220ms. I thought my STM4 suppose to much better link response time than the STM1 link?

Some one told that no matter how big the bandwidth of the line, physical location of the end point does play a role in this.

Can I know whether there is any formula that I can use to roughly predict the line latency based on physical location of the destination?

Giuseppe Larosa · ‎11-10-2008

Hello Chris,

the componenents of delay are:

serialization delay : depends from the bit rate: to place a block of B bits on a link of speed R bits/sec you need B/R

queueing delay: the time the packet waits to be sent out on the the physical interface output queue: negligible if the link is not saturated.

propagation delay:

the time it takes to move a bit of information from location1 to location2.

D = distance in km of the two locations = fiber length

c= speed light 3 10^5 km/s

N= refraction index of fiber > 1

(1 is air ) typical 1.48

the propagation delay is :

D * N /c

Hope to help

Giuseppe

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Giuseppe Larosa · ‎11-10-2008