XPost: comp.os.linux.networking   
   From: markhobley@yahoo.donottypethisbit.co   
      
   On Sun, 26 Sep 2010 16:20:45 +0200, jack wrote:   
      
   >   
   > None, if B is connected directly to C. Plenty, in the (somewhat extreme)   
   > case that B connects to C via routers R1, R2, and R3 with respective   
   > path MTUs of 1480, 1470 and 1450. B sends a 1500-byte packet; R1 splits   
   > it into a (1480+20). R2 splits that into (1470+10+20). R3 splits that   
   > into (1450+20+10+20). Now we have 4 packets, with the overhead of 3   
   > extra headers, that need to be re-assembled at C. And without PMTUD this   
   > will happen for every single packet larger than 1480.   
      
   My next question now is how likely is it that a router shunting internet   
   traffic has a maximum segment size of less than 1500, (before reaching   
   the destination network)? Is fragmentation en-route likely, or is this most   
   likely to start occuring on the destination LAN?   
      
   (In other words, are routers with an MSS of less than 1500 in common usage?)   
      
      
      
   >   
   > -j   
      
      
      
      
      
   --   
   Mark Hobley   
   Linux User: #370818  http://markhobley.yi.org/   
      
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