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.
when high RTT is involved an extended TCP window size can help.
the native size of TCP window is a 16bit integer only 65535 octets can be sent before waiting for ACK.
To be noted that are the endpoints that need to negotiate an extended TCP window: the router work ends at OSI Layer3, so you cannot find a command on a router to enable usage of extended TCP window on end devices.
You rather need to tune TCP/IP stack.
see for Windows XP
in data transmission the rates are expressed in bps or Mbps or Gbps
1Kbyte/s = 1024*8 bps
1Mbyte/s = 1024*1024*8 bps
and so on
Hope to help