HP Cisco MDS 9216 Cisco MDS 9000 Family Fabric Manager Configuration Guide, Re - Page 959

Chapter 48 Configuring FCIP Using the FCIP Wizard Send documentation comments to [email protected] • If the average rate of the Fibre Channel traffic is greater than min-available-bandwidth multiplied by the RTT, but less than max-bandwidth multiplied by the RTT, then if the Fibre Channel traffic is transmitted in burst sizes smaller than the configured CWM value the entire burst is sent immediately by FCIP at the max-bandwidth rate. • If the average rate of the Fibre Channel traffic is larger than the min-available-bandwidth multiplied by the RTT and the burst size is greater than the CWM value, then only a part of the burst is sent immediately. The remainder is sent with the next RTT. The software uses standard TCP rules to increase the window beyond the one required to maintain the min-available-bandwidth to reach the max-bandwidth. Note The default burst size is 50 KB. Tip We recommend that this feature remain enabled to realize optimal performance. Increasing the CWM burst size can result in more packet drops in the IP network, impacting TCP performance. Only if the IP network has sufficient buffering, try increasing the CWM burst size beyond the default to achieve lower transmit latency. Estimating Maximum Jitter Jitter is defined as a variation in the delay of received packets. At the sending side, packets are sent in a continuous stream with the packets spaced evenly apart. Due to network congestion, improper queuing, or configuration errors, this steady stream can become lumpy, or the delay between each packet can vary instead of remaining constant. You can configure the maximum estimated jitter in microseconds by the packet sender. The estimated variation should not include network queuing delay. By default, this parameter is enabled in Cisco MDS switches when IPS modules or MPS-14/2 modules are present. The default value is 1000 microseconds for FCIP interfaces. Buffer Size You can define the required additional buffering-beyond the normal send window size -that TCP allows before flow controlling the switch's egress path for the FCIP interface. The default FCIP buffer size is 0 KB. Note Use the default if the FCIP traffic is passing through a high throughput WAN link. If you have a mismatch in speed between the Fibre Channel link and the WAN link, then time stamp errors occur in the DMA bridge. In such a situation, you can avoid time stamp errors by increasing the buffer size. Advanced FCIP Interface Configuration This section describes the options you can configure on an FCIP interface to establish connection to a peer and includes the following topics: • Configuring Peers, page 48-22 • Active Connections, page 48-25 • Number of TCP Connections, page 48-25 OL-16184-01, Cisco MDS SAN-OS Release 3.x Cisco MDS 9000 Family CLI Configuration Guide 48-21