Thank you for the sanity check. We figured out it was a colocated customer
of our who turned on multicast to cluster his servers.
jon
----- Original Message -----
From: "Eric Barr" <[EMAIL PROTECTED]>
To: "CF-Talk" <[EMAIL PROTECTED]>
Sent: Wednesday, February 21, 2001 2:26 PM
Subject: OT: AOL Cache servers bringing down server?
> Let's see if I can take a crack at this.
>
>
> 1) Why are AOL servers on lots of different ports?
>
> This goes to the way that TCP/IP works. To make a connection over
> TCP/IP a unique IP addresses & Port combination is needed on each end.
> So for example: www.myserver.com (1.1.1.1) is running on port 80. As a
> client (coming from 2.2.2.2) if I want to see a web page I request a
> page from 1.1.1.1 on port 80. As part of this request I send the web
> server my IP Address and a randomly chosen port between 1025 and 65,536
> (or 32,786 in some cases), lets say its port 6,347 ...so the connection
> is :
> from 1.1.1.1:80 to 2.2.2.2:6347
> The 6347 is the port you are seeing as the port under the "Foreign
> Address" when you use netstat.
>
>
> 2) Why does AOL have 100's of connections?
>
> For each Unique request the client chooses a randomly chosen port in the
> range mentioned above. So when I download a single web page with 5
> images my client could potentially make 6 connections to the web server
> (1 for the page and 5 for the images) each originating from a unique
> port on my machine.
>
> So if your site is mildly popular among AOL users you will see their
> cache servers trying to cache all sorts of content off your site,
> resulting in those 200 connections
>
>
> 3) So why are these connections hanging around?
>
> Well this part of my knowledge is a bit shaky. Basically clients enter
> the TIME_WAIT state after and active connection closes. I guess it is
> time to stand on the shoulders of others ... MS knowledge base article
> Q137984 has the following paragraph about this condition:
>
> NOTE: It is normal to have a socket in the TIME_WAIT state for a long
> period of time. The time is specified in RFC793 as twice the Maximum
> Segment Lifetime (MSL). MSL is specified to be 2 minutes. So, a socket
> could be in a TIME_WAIT state for as long as 4 minutes. Some systems
> implement different values (less than 2 minutes) for the MSL.
>
>
> 4) Why is your web server not serving up some images ?
>
> I have no idea. But having these 200 connections from AOL doesn't sound
> like a cause for alarm if your site gets some good traffic. These
> connections most likely aren't killing your server.
>
>
> Hope this helps.
> -eric
> ------------------------------------------------
> Common sense is genius dressed in its working clothes.
> -- Ralph Waldo Emerson
>
> Eric Barr
> Zeff Design
> (p) 212.714.6390
> (f) 212.580.7181
>
>
> -----Original Message-----
> From: Jon Hall [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, February 20, 2001 3:32 PM
> To: CF-Talk
> Subject: AOL Cache servers bringing down server?
>
>
> I am about to go ballistic and block all AOL anything at the router but
> need
> a sanity check. Is it normal for AOL cache servers to have hundreds of
> open
> connections on a web server at once?
> One of my web servers has been acting weird and not sending images or
> just
> abort sending html in the middle of a page.
> I did a netstat and saw this over 200 times
> cache-rq01.proxy.aol.com:57324 TIME_WAIT
>
> All different aol cache servers and on different ports...
> Anybody seen this before? Is this normal?
>
> jon
>
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