Some notes for field technicians
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Re: TELNET
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Following info is relevant:

1. MSS that we advertise (meaning the largest receivable packet in TCP) is
   1500. This includes the TCP/IP/Ethernet headers. This is configurable
   in the NVRAM strings, but currently UI has no support for this. String
   is "TCP Maximum Segment Size".

   The relevance is that since we advertise 1500, other TCP clients are
   allowed to send packets as large as 1500. If at the lower layers, we
   have MRU's lesser than this, then we should be able to support fragmenting.

   If there are problems receiving and you come to know the sender is
   sending TCP packets larger than the MRU of a lower layer, try adjusting
   this to a value lesser than the MRU.

2. Our receive and send window size = 1.5K = 1536 bytes.
   This may affect size of packets that may be sent. See note below.
  
3. MSS that clients advertise is used by us to determine how much to
   packetise. If some client's advertise a value of 2048, then TCP might
   try to put as much as 1536 (as our send window is 1536 bytes) bytes in a 
   packet. The result is that we try to send a TCP packet of 1.5K. But if
   the lower level MTU is lesser than this, then IP will try to fragment.
   (IP fragmenting does not seem to be working properly in our router).

   So if you have fragmenting problems, try setting the CLIENT TCP's MSS
   value advertise (usually all clients have a config file where this can
   be set) to a value lesser than our MTU on the channel. Take care to
   deduct TCP/IP/Ethernet header sizes...

4. If the receive window of the client TCP is large, the client may
   not seem to respond initially for a large amount of time. This is seen
   with PC-TCP. Solution -- reduce the receive window size to less than
   1.5K. In PC-TCP use the "config" utility after running "ethdrv".


