RE: [SAGE] TCP Window Tuning for High Bandwidth/High Latency WAN links?

["John LLOYD" <jal@mdacorporation.com>]

> 1. tune the TCP settings on each host for all connections, which may
>    impact memory usage and won't do much of LAN connections if at all.

Getting this to actually work is nontrivial.  Having just one platform helps a lot.

 
> 2. turn the TCP window size on a per-server (ftp, ssh) and per-client
>    basis (ncftp, scp, etc).  Then training the users if the tuning
>    isn't automatic how to use it...
> 
> 3. Get a network box which will do this for us (yet more money...)
>    auto-magically at each site.  One option, which I have pricing on
>    at all is:
> 
> 	http://www.internap.com/products/FCP-solution.htm
> 
>    Though we won't be multi-homed in our WAN/VLAN setup at this time,
>    too much money.  


There was a review of network boxes in Network Computing a while ago...October?  One consultant website lists a bunch of vendors... http://www.gen2ventures.com/WAN%20Opt%20Workshop.htm

Packeteer is the leading vendor but they cost a bundle.  One of the vendor sites has an IDC report naming most of the other vendors too; look for it probably on the Packeteer site.  There is a bunch of consolidation going on in this market space so be wary of product line terminations as companies are bought up.

We are currently planning to use Xiphos XIPlink in a wideband application.  (xiplink.com)  Not yet implemented so I can't say how well it works.  Not as expensive as the other guys.

There are a couple of vendors with very smart caching servers, with large disk farms on their back ends.  They claim to shrink large file transfers down to "cache plus deltas", rapidly speeding up transfers.  Probably not NFS-compatible, but they do FTP.  A lot of data is copied multiple times, it seems.

Other possibilities include UDP file transfers (no TCP delay-bandwidth product); there aren't any generic utility programs ("udp-ftp") that I've been able to find, but there are some specific applications such as Linux cluster-boot utilities that could be adaptable.  These tend to aim at the multi-casting of files.


> 
> So it all comes down to what other people have done and/or are doing
> in this type of situation?  What solutions have your deployed?  As WAN
> links get faster, yet the RTT time doesn't shrink, TCP is going to
> need some interesting hacks to make it work better in this situation.
> 
> Thanks,
> John
> 

There is a whole bunch of experience in the Internet2 realm, using ATM and other links (terrestrial and satellite) going back a few years.  Remote ISPs reliant on satcom links have experience too, but they're more into the dozens of concurrent transfers and not just a few fast ones.

Most of the larger universities in North America have wideband links to various regional and national networks, CA*net in Canada, and a bunch of ones in the U.S.  A few phonecalls to nearby Universities might uncover some experienced sites with guidelines and pointers to freeware/methods/gotchas.  If they aren't already on this list, that is.


--John