Filter
Top Products
Send documentation comments to mdsfeedback-doc@cisco.com.
19-4
Cisco MDS 9000 Family Fabric Manager Configuration Guide
OL-6965-03, Cisco MDS SAN-OS Release 2.x
Chapter 19 FCIP Configuration
FCIP Write Acceleration
FCIP Write Acceleration
The FCIP write acceleration feature in Cisco MDS SAN-OS Release 1.3(3) enables you to significantly
improve application performance when storage traffic is routed over wide area networks using FCIP.
When FCIP write acceleration is enabled, WAN throughput is maximized by minimizing the impact of
WAN latency for the command to transfer ready acknowledgments (see Figure 19-3).
Note The write acceleration feature is disabled by default and must be enabled on both sides of the FCIP link.
If it is only enabled on one side of the FCIP tunnel, the tunnel is not initialized.
Figure 19-3 FCIP Link Write Acceleration
In Figure 19-3, the write command without write acceleration requires two round-trip transfers (RTT),
while the write command with write acceleration only requires one RTT. The maximum sized Transfer
Ready is sent from the host side of the FCIP link back to the host before the write command reaches the
target. This enables the host to start sending the write data without waiting for the long latency over the
FCIP link of the write command and Transfer Ready. It also eliminates the delay caused by multiple
Transfer Readys needed for the exchange going over the FCIP link.
FCFC
FCIP over
WAN
105224
Initiator MDS 9000 MDS 9000 Target
Transfer ready
Transfer ready
Transfer ready
Command
Command
Data transfer
Data transfer
Status
Status
Without
acceleration
RTT1
RTT1
RT2
FCFC
FCIP over
WAN
Initiator MDS 9000 MDS 9000 Target
With
acceleration