Re: improving transport over lossy links ?

Hi Mike,

On Sun, 21 May 2006 at 16:03:39 -0400, Mike Tancsa wrote:

Correct. Its always dialing into a terminal server that is connected
via PRIs. Usually Lucent PM3, sometimes Cisco 5800s depending on the
location they dial from.

I guess you won't want to be messing with their configs, then ..

> The internal USR seems to correctly see the carrier drop and PPP
> hence sees it. However, the 2 external Intels I am experimenting
> with on the USB serial ports do not. I suspect thats part of the
> reason the DCD is not working. Perhaps incorrect init string or
> something with the USB-Serial. Note, I only have the internal USRs
> deployed in the field right now

Don't know about USB modems. Do USR still use their own chipsets, or
what? In any case, they're probably highly tunable and well documented.

Actually, they are just regular external modems connected to USB to
serial adaptors (using the uftdi driver)

I had a browse through /sys/dev/usb/{uft,ucom}* but was well out of my
depth .. it =looks= like DCD (aka RLSD) changes should be picked up ok;
perhaps you're right about some odd init string or such - good luck!

Not V.90 full tilt, anyway. If 45333 is sort of usual for this one,
then I'd probably try telling it to connect no higher than maybe 41333
or 40000; often about 10-15% or so less than 'normal' can make all the
difference. If you can afford the bandwidth, go for slow and solid ..


Yes, for sure I will try and lower the speeds a bit, but ultimately I
want to deal with situations where the carrier drops and the modem
has to redial. The client is willing to put in an extra phone line
if it would make the link more reliable. Typically these sites are
too remote for other types of transport. I think if I can get mp
working with reliable dcd I think that should do it.

Fair enough. Chances of losing two lines at once are pretty small,
unless there are district-wide problems, given you get DCD going ..

cheers, Ian

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