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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