Thomas Bohn wrote:
>
> All:
>
> Please excuse this post if inappropriate.
>
> Am seeking any interest in an opportunity to test research
> projects/products in a working satellite environment: am working on a US
> Federal telehealth project in the state of Alaska -- we have a statewide
> network interconnected by a combination of satellite-based and terrestrial
> T1 and sub-DS1 links. We have developed a web-based application for
> digital acquisition of medical imagery in remote areas, with a
> store-and-forward function for referral of medical data to distant
> providers/specialists. The application has been developed on Win2K
> platforms (both client and server) using ColdFusion middleware and SQL
> database backends. I am currently porting the application to Linux.
>
> We have run into the well-known snag with sat links and TCP: short bursty
> data transfers over TCP don't do so well on high-band/long delay nets.
>
> I am seeking information related to Open Source TCP stack modifications
> for a web proxy to be placed on the web server LAN in order to accelerate
> the transfer of data out over the WAN to distant client machines. We do
> *NOT* want to modify the stack on the webserver itself, but on an
> accelerating proxy for outlying satnet clients.
>
> Our network is private, e.g. is NOT connected to the public Internet. We
> are built out on RFC 1918 address space, use Cisco network elements and
> standard transport offerings from Alaska-based space segment providers.
>
> If anyone on this list has an interest in testing within such an
> environment (whether your solution is commercial or non-commercial) we
> would like to speak with you. We are, as stated, seeking non-commercial
> Open Source variants of standard TCP implementations -- primarily on the
> sender side. Link layer framing is typically standard serial, as
> ATM-based cell protocol offerings in the Alaska market were recently
> pulled by AT&T (e.g. we use HDLC, PPP, etc.)
Sounds like what you want to do is:
- run HTTP 1.1 (or at least +persistent connections, which predates 1.1)
- turn TCP's congestion management
one way to do this using private space is to have the endpoints
on the same subnet. that causes many implementations to turn
off congestion management
- use large MTUs (the same trick - same subnet will trigger use of link MTU
rather than path MTU discovery, but be careful of black holes if that size
is too large -- it can be reset at the interfaces themselves)
- make sure your socket buffers, etc are tuned properly (see www.psc.edu)
Note that none of these necessitate the use of a proxy.
Some can be implemented at the proxy, but that runs the risk
of having the proxy be the bottleneck.
Joe
This archive was generated by hypermail 2b29 : Thu Feb 01 2001 - 18:02:40 EST