6ec810d4   
   From: grahn+nntp@snipabacken.se   
      
   On Tue, 2012-04-24, Madhur wrote:   
   > On Apr 24, 6:00 am, Jorgen Grahn  wrote:   
   >> On Tue, 2012-04-24, Madhur wrote:   
   >> > Hi,   
   >>   
   >> >     I am having a setup as given below   
   >>   
   >> > (TCP client)Mobile ---[Wireless]----Station 1---[ethernet]-----   
   >> > Station2---[ethernet]----Station 3(TCP Server)   
   >>   
   >> > TCP client is pulling data from TCP server. When I am trying to do   
   >> > this I Observe TCP payload size between at Station 2 I observe data   
   >>   
   >> I guess "between at Station 2" means "to the right of 2"?   
   >>   
   >> > packet sizes in multiples of MTU sizes like, 3000, 4500, 6000,...   
   >>   
   >> What does this mean? The MTU is the max size of the Ethernet data, and   
   >> you seem to say MTU is 1500 on those links. So are you saying you see   
   >> up to four IP fragments for each IP datagram? That seems crazy.   
   >>   
   >> > The   
   >> > application/forwarding agent at Station 2   
   >>   
   >> Uh, what's an "application/forwarding agent"? Isn't it just a router   
   >> you have there?   
   >>   
   >> > expects packets of size 1500   
   >> > or less only. Hence packets are dropped at Station 2. After 300ms, TCP   
   >> > is retransmitting packets with smaller packet size(<1500) and hence it   
   >> > reaches TCP Client. Eventually i observe poor throughput.   
   >>   
   >> > I am very greatful if someone points to me, as why I am finding packet   
   >> > sizes more than 1500 bytes at station 2. I have tried setting TCP MSS   
   >> > at TCP server. MTU sizes on interfaces are 1500. The negotiated MSS is   
   >> > less than 1500. I am clueless.   
   >>   
   >> I kind of suspect you're describing a path where MTU is small S1--S2,   
   >> but you have jumbo frames S2--S3 ... but that is just a guess, and if   
   >> it's a correct guess I don't understand why you didn't simply say so.   
   >>   
   > Yes.. that is right. Looks like Jumob frame between S2 and S3. How to   
   > turn off jumbo frames?   
      
   I don't know. The right way do deal with this is supposed to be Path   
   MTU Discovery.  I don't know much about other workarounds.   
      
   /Jorgen   
      
   --   
     // Jorgen Grahn    O  o   .   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)