o If suspect network problems, check line counters on various nodes:

      BIRCH$ mcr ncp
      NCP>show known_line_counters
      NCP>show known line counters


      Known Line Counters as of  9-MAR-2001 09:37:19

      Line = EWA-0

            >65534  Seconds since last zeroed
         331016861  Data blocks received
          17282229  Multicast blocks received
                 0  Receive failure
       >4294967294  Bytes received
        1355271977  Multicast bytes received
                 0  Data overrun
         334089510  Data blocks sent
            577865  Multicast blocks sent
                 0  Blocks sent, multiple collisions
                 0  Blocks sent, single collision
                 0  Blocks sent, initially deferred
       >4294967294  Bytes sent
          61674014  Multicast bytes sent
                 0  Send failure
                 0  Collision detect check failure
                59  Unrecognized frame destination
                35  System buffer unavailable
                 0  User buffer unavailable

  "Receive failure", "Send failure", and "Collision detect check failure"
  counters should all be zero, or at least tiny.