Re: Pushing more than 936kb/sec via satellite

[Brad Smith <[e-mail]>]

Hank Nussbacher wrote:
> 
> I have read over:
> http://www.ietf.org/internet-drafts/draft-ietf-tcpsat-stand-mech-06.txt
> and have some questions.  I am not on your list, so please remember to reply
> also directly to me.
> 
> Today, is there any way without modifying the TCP stacks in NT, W95, AIX,
> Solaris, SG, HP, etc. to push more than 936kb/sec via satellite?  

Not that I'm aware of, operationally. YMMV.

> Can one
> put a black box on each end and fake things out (window size, ACKs, NAKs,
> etc.) for all TCP streams so as to get 20-30Mb/sec per TCP stream via GEO
> satellites?  Does anyone know anyone doing this?  

Theoretically, yes.  Personally, I've been playing with an extremely
rudimentary system that consists of two BSD boxes (one at either end of
the GEO link) that essentially function as circuit level relays.  On the
BSD ---- BSD GEO link, timing mechanisms are disabled, and the window is
propped open to something obscene (2GB).  Works OK, but there are
problems with it.  I'm quite sure a better programmer could do a better
job. Of course, I don't have 30Mb/s of xpndr space to play with, but my
test data says it should scale.

> Does anyone know of
> equipment that can handle T3/OC-3 speeds?

For DS-3 I'd look at the Raydine DM-45.  EFData's SDM-155 should do the
trick for OC-3.  I have no personal experience with either of these
devices so again, YMMV.

Of course, there's always the DVB route.  I'm just not partial to the
idea of running all my IP traffic through a DVB head end system. 
Particularily when that head end system runs Windows NT.

> 
> What if the GEO satellite link was simplex with a fiber uplink?  This would
> alter the numbers - has anyone had any experience with hybrid systems being
> able to pump 20-40Mb/sec per single TCP stream?
> 

My customers configured in this manner generally get about 15 - 20%
better performance.  Again, I don't have the xpndr capacity to tell you
anything about a 20 - 40 Mb/s stream, but the 4 and 8 Mb/s customers are
pretty happy.


--brad