Changing Tcp Parameters - Cisco MDS 9000 Series Troubleshooting Manual

Chapter 5 Troubleshooting IP Storage Issues
S e n d c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m .
(This is the window size set on the IPS iscsi interface. See
Figure 5-15 Congestion window: Current: 24 KB

Changing TCP Parameters

To change TCP paramaters in the Windows registry use the Registry Parameters above as an example.
Setting the Tcp1323Opts (marked green) to 3, sets two bits ON, one for Window Scaling, the other for
the TimeStamp Option. We are only interested in the Window Scaling here. User should be aware that
editing registry is a high risk operation and can render the System unusable requiring a reinstall of the
whole operating system !! Only advanced users should do this.
MDS_BOTTOM# show interface gigabitethernet 2/1
GigabitEthernet2/1 is up
(Better throughput can be achieved if the MTU of both the client NIC, as well as the IPS Gigabit interface
is changed for higher MTU, provided the network in the middle supports jumbo frames.)
OL-5183-02, Cisco MDS SAN-OS Release 1.3
Hardware is GigabitEthernet, address is 0005.3000.a85a
Internet address is 10.48.69.251/26
MTU 1500 bytes, BW 1000000 Kbit
Port mode is IPS
Speed is 1 Gbps
Beacon is turned off
Fine Tuning/Troubleshooting IPS iSCSI TCP Performance
Figure 5-15.)
Cisco MDS 9000 Family Troubleshooting Guide
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