HP StorageWorks Fabric OS 6.2 administrator guide (5697-0016, May 2009)

488 Configuring and monitoring FCIP extension services
WAN tool performance characteristics
Table 96 lists the end-to-end IP path performance characteristics that you can display using the portCmd
ipPerf command and option. All four of the base ipPerf performance characteristics (bandwidth, loss,
RTT, PMTU) are provided in the command output in Fabric OS 5.2.0 or later.
WAN tool analysis
Typically, you start the WAN tool before setting up a new FCIP tunnel between two sites. You can configure
and use the
--ipPerf option immediately after installing the IP configuration on the FCIP port (for
example, IP address, route entries). Once the basic IP addressing and IP connectivity is established
between two sites, you can configure
--ipPerf with parameters similar to what will be used when the
FCIP tunnel is configured.
The traffic stream generated by the WAN tool ipPerf session can be used for the following functions:
• Validate a service provider Service Level Agreement (SLA) throughput, loss, and delay characteristics.
• Validate end-to-end PMTU, especially if you are trying to eliminate TCP segmentation of large Fibre
Channel (FC) frames.
• Study the effects and impact FCIP tunnel traffic may have on any other applications sharing network
resources.
To start an
--ipPerf session, you can use any port as long as the port (in combination with local
interface) is not in use. You must run the
--ipPerf client on both the host (source mode, -S option) and
receiver (sink mode, -R option). See ”WAN tool ipPerf syntax” on page 489 for more information about
specifying source and sink mode.
Starting an ipPerf session
1. Configure the receiver test endpoint using the CP CLI.
The syntax for invoking the receiver test endpoint using
--ipPerf for slot8, port ge0 on a B-Series
Multi-Protocol Router Blade is as follows:
portcmd --ipperf 8/ge0 -s 192.168.255.10 -d 192.168.255.100 -R
2. Configure the sender test endpoint using a similar CP CLI.
The syntax for invoking the sender test endpoint using
--ipPerf for slot8, port ge0 on a B-Series
Multi-Protocol Router Blade is as follows:
portcmd --ipperf 8/ge0 -s 192.168.255.100 -d 192.168.255.10 –S
Table 96 WAN tool performance characteristics
Characteristic Description
Bandwidth Indicates the total packets and bytes sent. Bytes/second estimates are maintained
as a weighted average with a 30 second sampling frequency and also as an
average rate over the entire test run. The CLI output prints the bandwidth observed
in the last display interval as well as the Weighted Bandwidth (WBW). BW
represents what the FCIP tunnel / FC application sees for throughput rather than
the Ethernet on-the-wire bytes.
Loss Indicates the loss estimate is based on the number of TCP retransmits (assumption
is that the number of spurious retransmits is minimal). Loss rate (percentage) is
calculated based on the rate of retransmissions within the last display interval.
Delay Indicates TCP smoothed RTT and variance estimate in milliseconds.
Path MTU (PMTU) Indicates 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.
There is a limited support for black hole PMTU discovery. If the Jumbo PMTU
(anything over 1500) does not work, ipPerf will try 1260 bytes (minimum PMTU
supported for FCIP tunnels). If 1260 PMTU fails, ipPerf will give up. There is no
support for aging. PMTU detection is not supported for active tunnels. During
black hole PMTU discovery, the BW, Loss, and PMTU values printed may not be
accurate.