North American Network Operators Group
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Re: TCP and WAN issue

  • From: Joe Maimon
  • Date: Tue Mar 27 18:39:15 2007


Philip Lavine wrote:

I have 2 data transmission scenarios:

1. Microsoft MSMQ data using TCP
2. "Streaming" market data stock quotes transmitted via a TCP sockets

Philip

TCP stack tuning works very well for applications with large sized network reads and writes.

Applications that will only write X and then will wait to read Y do not gain from tweaks when Y or X are not large enough to fill a significant portion of the pipe end to end. IOW, the chattiness of the protocol multiplied by the rtt equals delay.

Applications that open and close sockets to chat are even worse.

The only real thing that can cure this other than a rewrite of the applications behavior, is a application layer proxy that "chats on behalf of"

This is part of the wan optimization space from what I understand.




----- Original Message ----
From: William F. Maton Sotomayor <[email protected]>
To: Philip Lavine <[email protected]>
Sent: Tuesday, March 27, 2007 2:50:44 PM
Subject: Re: TCP and WAN issue


Hi Philip,

We've run across this problem from one end of Canada to the other. As others have alluded to, the best you can hope for is to tweak the TCP window sizes up and increase the socket buffers to suit. However, if you're doing something over NetBIOS, it's turned out to be a total lost cause. Right now we're looking at the Steelheads from Riverbed to solve the NetBIOS problem. (The Steelheads do the dirty work of TCP tweaking on your behalf, so you don't have to, besides cacheing.)

BTW, when you say stream, you're saying transfer of data other than a webcast, correct?

On Tue, 27 Mar 2007, Philip Lavine wrote:


This is the exact issue. I can only get between 5-7 Mbps. So the question is really what incremental performance gain do WAN accelerators/optimizers offer? Can registry/OS tweaks really make a significant difference because so far with all the "speed enhancements" I have deployed to the registry based on the some of the aforementioned sites I have seen no improvement.

I guess I am looking for a product that as a wrapper can multiplex a single socket connection.

Philip

----- Original Message ----
From: Robert Boyle <[email protected]>
To: Philip Lavine <[email protected]>; nanog <[email protected]>
Sent: Tuesday, March 27, 2007 2:04:20 PM
Subject: Re: TCP and WAN issue

At 04:26 PM 3/27/2007, Philip Lavine wrote:

I have an east coast and west coast data center connected with a
DS3. I am running into issues with streaming data via TCP and was
wondering besides hardware acceleration, is there any options at
increasing throughput and maximizing the bandwidth? How can I
overcome the TCP stack limitations inherent in Windows (registry
tweaks seem to not functions too well)?


You will have problems obtaining anything more than 5-7Mbit/s based
on 1500 byte Ethernet packets and a RTT latency of 70-90ms. You can
increase your window size or use Jumbo Ethernet frames. Almost all
GigE gear supports jumbo frames. I'm not sure of your application,
but without OS tweaks, each stream is limited to 5-7Mbit/s. You can
open multiple streams between the same two hosts or you can use
multiple hosts to transfer your data. You can utilize the entire DS3,
but not without OS TCP stack tweaks or a move to jumbo frames. You
can also use UDP or another connectionless packet method to move the
data between sites. Good luck.

-Robert



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