Latency and NAT

B

Brink

Limp Gawd
Joined
Jan 3, 2003
Messages
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This post is somewhat related to a previous post I made a while back:

http://www.hardforum.com/showthread.php?s=&threadid=676768

reading it isn't entirely neccessary but it'll show how I came to asking this question and gives a little background into a real world problem I had a couple months back that I wasn't really able to solve.

So the question is, can extremely bad latency (say in the 2000ms range) hinder NAT? Under those conditions the serving computer would experience a greater speed than the clients?

I don't know too much about latency and it's effect on NAT. My impression is, if latency is bad on 1 computer, even if that computer shares it's connection, it shouldn't hinder the bandwidth of the share-ees too much (atleast not THAT much).

Really you should just be adding a little extra delay for that extra little hop between computers.
 
I'm not sure if I'm with you all the way, but let me see what I can figure out.

You have a win2k system set up with ICS. We'll call that ICS-1. It has 2 clients, client-1 and client-2. Client-2 is trying to connect to websvr-1. ICS-1 uses a sat connection which has a standard ping of 2000ms (2 seconds) to the average website. That high latency isn't surprising at all with sat connection. But your bandwidth is just fine...say 1.5mbps.

So the question is what should client-2's pings to websvr-1 be like? Assume 1ms for a good lan connection, that same amount for the NAT routing, and you should be around 2002ms. NAT and ICS should be near transparent for ping times, as should lan traffic.

Will the serving computer (websvr-1) care about nat? No. It won't know that NAT is even running since all of the nat processing happens on ICS-1. As far as websvr-1 is concerned, it is ICS-1 which is requesting the page, but as each packet hits ICS-1 than NAT takes over, re-encapsulates the packet and routes it on to client-2.

Ping times (and bandwidth) between ICS-1, client-1 and client-2 should be unaffected by NAT (it isn't running on local lan traffic) or any latency issues that might effect traffic going out to the wan connection (sat connection).

Honestly, I haven't the slightest clue if I came even close to answering your questions. Let me know if I totally missed the point.
 
well you have it pretty much. I guess I should have included a bandwidth question as well. In the first problem I had the Serving computer (ICS-1) was receiving pretty near it's CIR. However any clients, wireless or directly connected, got a severe fraction of that speed.

In the former post a suggestion was TOS shaping possibly effecting it. Which could have been it (but I think only WinXP does this by default). Then again, this was a Win2k computer explicately configured by this Satelite ISP service. Him sharing the connection was probably not covered by their support service and thus I was called in.

Even then, TOS wouldn't cut the numbers like they did. What was about 768 down cut to about 50-60Kbps on the client computers? I don't think so.
 
2000ms is standard on a sat connection? Struth...

The way I read his post I would have answered the same way so I would assume you hit the nail on the head. If not like Buckeye said let us know. Im not 100% sure what your asking.

Cheers
 
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