5–Fibre Channel over IPConfiguring FCIP5-10 ISR651101-00 ELink Data RateThe available link data rate is not typically the same as the connection speed atthe router’s GE port. The GE port is typically connected to a local IP switch withports running at 1 gigabit. The provider of the long-distance connection (WAN)provides the link data rate. Table 5-2 lists some examples of data rates forcommonly used WANs.In some configurations, the data rate (bandwidth) supported by the WAN may notbe dedicated to a single application such as FCIP. The ability to set the router'sFCIP bandwidth usage provides for such configurations (see “Bandwidth Limiting”on page 5-14).Link QualityThe link (WAN) quality can be difficult to determine; however, monitoring therouter's statistics should provide an indication of the overall link quality. Typically,low link level errors are not seen at the router because they generally occur in theWAN.The following TCP statistics are a useful indicator of WAN congestion or packeterrors: TCP Received Duplicate ACKs—Receiving a duplicate ACK indicates thatthe receiver did not receive the packet following the ACK’d packet (packetwhose sequence number follows the ACK'd packet). This is typically theresult of the following: Congestion: An IP switch or router somewhere in the WAN hasdropped the packet due to its inability to transmit or buffer the packet. Error: The packet was dropped somewhere in the WAN as a result ofthe detection of a data error (corruption).Table 5-2. WAN Data RatesLink Type SpeedT1 and DS-1 1.554MbpsT3 and DS-3 45MbpsOC-1 50MbpsOC-3 150MbpsDS-5 400MbpsOC-12 621MbpsOC-24 1.5Gbps
