Re: TCP Window Size

On May 31, 8:45 am, Cheema <atif_che...@xxxxxxxxx> wrote:
Hi

I would like to share my experience. We have a data base application
with record of 30 million people.

PROBLEM : Slow application access from time to time

Server : data base application

WAN : 12Mbps of clear pipe end to end WAN links

client : A Thin and Terminal Server serving 200 thin/terminal server
clients

Util% : WAN links are max 60% loaded

RTT : 20-120 msec with average RTT of 58msec

Server TCP Window Size : 24kByte

Client TCP Window Size : 65kByte

I have strong understanding that this is due to the SENDER and
RECIEVER capacity mismatch

Kindly advise on this situation

What TCP window size should be used ?

Should it be changed on both ends ?

can FAST TCP be applied in this scenario ?

Waiting for your valuable answer

Thanks

Just from my experience, I have a hard time blaming TCP windowing.
How many concurrent users? Is this real time? How do the queries
look? Are they efficient? What kind of bandwidth per user or per
transaction, and how many users/transactions at any given time?
12Mbps is not that fast, but you need to provide context of whether or
not 12Mbps is enough. Could be anything from server being busy with
backups or some kind of schedule, to WAN pipe utilization going over
80% which would start to impact latency, to service provider, to
anything. Have you used MRTG or Netflow to gauge bandwidth
utilization at these times? How about latency? Do you have a
baseline of these usages and performance during 'good performance'
times? Do you have QoS? Could someone be running a FTP and killing
your pipe?

I won't say that packet/frame sizes are NOT the issue, but I just hate
to look at fundamental networking architecture when there are WAY too
many other variables that are more likely. Not to mention, window
sizes fluctuate, and if this is small telnet or shell based
application, they will most likely never get to full size.

.

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