Slow transfer (TCP) rate between sites

[vincent-n]

Hi all

Here's a scenario, I have two remote sites connected to HQ via an MPLS network. HQ has 200Mbps and the two sites both has 10Mbps links. Ping from HQ to HK (hong kong) is 180ms avg and ping from HQ to KL (kuala lumpur) is 121ms. Found that application responses at HK is a lot slower than KL. Did FTP transfer tests between HQ and the two sites and found that KL is able to achieve close to 450KByes/sec transfer (single session) while HK is doing ~180KBytes/sec at the most. Questions are:

1. I read about BDP (bandwidth delay product)http://en.wikipedia.org/wiki/Bandwidth_delay_product. IF my math is correct:

A. SIN = (10,000,000 * 0.121)/8 ~ 147.7KByes/sec transfer (on single sess)

B. HK = (10,000,000 * 0.18)/8 ~ 219KBytes/sec transfer (on single sess)

Anyone care to comment on th formula PLEASE !!!!! Something is wrong here.

Also, I could not find any references for IOS 'c2800nm-spservicesk9-mz.124-19b.bin' that would allow me to modify the TCP window size between clients on the LAN. I heard about the registry 'tweak' on MS Windows that allows larger TCP window but ....

1. I"m not sure if this is the underlying problems or not

2. Why is it that it only affect HK and not KL?

3. I'm using the same ISP but I know that the 'tail ends' are provided by different 3rd party vendor.

4. The config between KL and HL are almost identical (I used template)

5. The engineer at HK keeps on telling me that it's the TCP window size that cause the problem.

Any suggesion is greatly appreciated.

[vincent-n]

Ok, attached are the Visio diagram and a PDF version of the same diagram. Also attached are the configs. Thanks for your suggestions. Files are posted in two parts due to max 3 attachments per post.

[vincent-n]

And here are the configs. Please note that the carrier's engineer was able to achieve more than 6Mbps transfer rate between 2 x Linux PCs located at SYD and HK POPs. His delays (in ms) is just the same as what I've got and we're running over the same circuit internationally. Like I mentioned before, I was able to achieve slightly higher results by tweaking the registry with the TCP settings but just simply would not be able to achieve similar result as the engineer.

[Joseph W. Doherty]

You need to run down the problem you were seeing in your Wireshark snifs.

Since the carrier engineer is seeing expected perforamance and you're not, issue might be between POP and your HK site.

As example, it took me two months to get a 1st tier carrier to find a problem that I believed was in their network (and it was). Turned out to be L2 issue caused by buggy firmware on a line card on one of their devices. Device was incorrectly dropping packets.

Have you tried performance tests between KL and HK?

If you're using some variant of TTCP, can it provide "verbose" stats, like packet retranmissions?