From: gah@ugcs.caltech.edu   
      
   Rick Jones  wrote:   
   > Moe Trin  wrote:   
      
   (snip)   
   >> You said they're back-to-back, so the only thing I can think of is this   
   >> is a artifact of the receiving system not being aware that jumbos were   
   >> in use.   I don't know.   
      
   > Indeed - it is an example of two stations in the broadcast domain who   
   > were using different frame/MTU sizes :)   
      
   >> >Now, perhaps in your situation when you shrank the MTU to < 1500   
   >> >bytes, the ethernet controller and NIC were still willing to take-in a   
   >> >frame larger and IP accept it.   
      
   (snip)   
      
   Some years ago, I had a SLIP line running office to home at 9600 baud   
   using the usual SLIP MTU, which I believe is 1008. (That was just   
   at the beginning of the web, so mostly telnet, ftp, mail.)   
      
   > The "minimum 'maximum'" IP datagram size relates to IP fragment   
   > reassembly.  A conforming IP(v4) implementation must be able to   
   > reassemble IP datagrams of at least 576 bytes.  That is distinct from   
   > the minimum MTU for an IPv4 network, which if I recall correctly is 68   
   > bytes.   
      
   As I understand it, there are hosts, usually routers, that can   
   route larger datagrams, but can't process ones addressed to them   
   larger than 576 bytes.   
      
   I did find some hosts that didn't understand PMTUD while running   
   that SLIP line. It might be that at one time I changed all my   
   home hosts to 1008.   
      
   -- glen   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)