text: The link quality and bandwidth play a large role. Your network provider likely ensures a 
  latency maximum on your network link. Therefore, be sure to stay as far beneath the Global 
  Mirror round-trip-time (RTT) limit as possible. You can easily double or triple the expected 
  physical latency with a lower quality or lower bandwidth network link. Then, you are within the 
  range of exceeding the limit if high I/O occurs that exceeds the existing bandwidth capacity. 
  
  When you get a 1920 event, always check the latency first. The FCIP routing layer can 
  introduce latency if it is not properly configured. If your network provider reports a much lower 
  latency, you might have a problem at your FCIP routing layer. Most FCIP routing devices have 
  built-in tools to enable you to check the RTT. When you are checking latency, remember that 
  TCP/IP routing devices (including FCIP routers) report RTT by using standard 64-byte ping 
  packets. 
  
  In Figure 11-155, you can see why the effective transit time must be measured only by using 
  packets that are large enough to hold an FC frame, or 2148 bytes (2112 bytes of payload and 
  36 bytes of header). Allow estimated resource requirements to be a safe amount because 
  various switch vendors have optional features that might increase this size. After you verify 
  your latency by using the proper packet size, proceed with normal hardware troubleshooting. 