[e2e] Re: crippled Internet

Graham Knight G.Knight at cs.ucl.ac.uk
Thu Apr 26 06:29:57 PDT 2001


>again, in my limited experience, the speed of light in fiber and copper are
>dominate the mode of the measured delays.  though i could imagine that
>codecs and the like will make their contribution.

... but presumably these do not contribute to jitter and jitter ends up 
being traded for delay in playout buffers. Apart from the end-system things 
Jon C pointed his finger at, I presume the main source of jitter from 
within a network is queuing delays at routers. Is this actually the case 
and, if it is, is jitter (roughly) proportional to the number of routers on 
the path? I note that it takes about 10 hops to get from my home to outside 
the UK academic network.

>it seems more relevant to me that voip is two *separated* one way paths.
>what's to echo?

A few years ago I played with an Ethernet-ISDN gateway which supported 
voice. Echo was certainly noticeable when the delay was large enough. I 
think the echo was mainly due to acoustic coupling between mike and speaker 
in a conventional telephone hand-set.



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