Technical data

BCSM IN A NUTSHELL 2008
© 2008 Brocade Communications Systems, Incorporated.
Page 36 of 44
6.3 MAINTAINING SAN EXTENSION SOLUTIONS
VALIDATE THE IP NETWORK
Verify the IP interface and FCIP tunnel settings with the ipPerf tool and the portcmd -–ipperf
[slot]/port command
• Always specify local GbE port, the source IP (-s) and destination IP (-d), and whether this port is
the sender (-S) or receiver (-R)
• Start the ipPerf receiver first (-R), then start the ipPerf sender (-S)
• If no time interval is specified, type Ctrl-C on the sender to stop
• Can be run on an active tunnel
The portcmd --ipperf [slot]/port command output on the sender displays end-to-end IP path
performance values
• Updated in real-time, according to the time and test interval
• Two bandwidth values: BW and WBW
B7500:admin> portcmd –ipperf ge0 –s 192.168.23.100 –d 192.168.20.10 –R
ipperf to 192.168.20.10 from IP interface 192.168.23.100 on /0:3227
B48000:admin> portcmd –ipperf 10/ge0 –s 192.168.20.10 –d 192.168.23.100 –S
ipperf to 192.168.23.100 from IP interface 192.168.20.10 on 10/0:3227
30s: BW:118.86MBps WBW(30s): 58.01MBps Loss(%):0.00 Delay(ms):1PMTU:2348
<Truncated Output>
As you can see from the command output, jumbo frames are supported from the PMTU.
BW represents what the FCIP tunnel / FC application throughput rather than the Ethernet on the wire
bytes.
WBW represents what the FCIP tunnel / FC application throughput rather than the Ethernet on the wire
bytes.
Loss (%) is the number of TCP retransmits. This number is an average rate over the last display interval.
Delay (ms) is the TCP smoothed RTT and variance estimate in milliseconds.
Path MTU is the largest IP-layer datagram that can be transmitted over the end-to-end path without
fragmentation. This value is measured in bytes and includes the IP header and payload. A value of 2148 or
larger indicates that jumbo frames are supported in the network.
In the example above, two switches are connected via FCIP (port ge0 on 7500, and port 10/ge0 on 48000).
After creating IP interfaces on the appropriate GbE ports, the ipPerf utility is launched, with 7500 as the
receiver, and 48000 as the sender. The command output on each switch notes the “to” and “from”
addresses, as well as the slot/port indicator (slot 0 is the motherboard on the Brocade 7500).
As part of the verification, the packet loss and round trip delay can be used to validate that the tunnel is
performing as the WAN provider claims.