Cisco MDS 9000 Series Troubleshooting Manual page 148

Fine Tuning/Troubleshooting IPS iSCSI TCP Performance
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 .
If you do not have access to the host, one way to see if the host is also configured for high MTU/MSS
(as well as the path in the middle) is to check the split packets field in the show ips stats tcp display :
However this is a generic display for all TCP sessions. That is, if you have some Hosts with high
MTU-capable NICs, and some others without, it may be difficult to assess which is which.
MDS_Top# show ips stats tcp interface gig 2/1 detail (truncated output)
TCP Statistics for port GigabitEthernet2/1
TCP send stats
.........
TCP Active Connections
MDS_Top#
Afterward, traffic starts flowing from the FC storage towards the server that is connected via iSCSI to
the IPS.
MDS_Top# show ips stats tcp interface gig 2/1 detail (truncated output)
TCP Statistics for port GigabitEthernet2/1
TCP send stats
.........
Cisco MDS 9000 Family Troubleshooting Guide
5-54
10 segments, 240 bytes
5 data, 5 ack only packets
0 control (SYN/FIN/RST), 0 probes, 0 window updates
0 segments retransmitted, 0 bytes
0 retransmitted while on ethernet send queue, 0 packets split
Local Address Remote Address
10.48.69.250:3260 10.48.69.233:1026
10.48.69.250:3260 10.48.69.233:1040
0.0.0.0:3260 0.0.0.0:0
715535 segments, 943511612 bytes
712704 data, 2831 ack only packets
0 control (SYN/FIN/RST), 0 probes, 0 window updates
0 segments retransmitted, 0 bytes
0 retransmitted while on ethernet send queue, 345477 packets split
Chapter 5 Troubleshooting IP Storage Issues
State Send-Q Recv-Q
ESTABLISH 0 0
ESTABLISH 0 0
LISTEN 0 0
OL-5183-02, Cisco MDS SAN-OS Release 1.3