HP StorageWorks B-Series Remote Replication Solution Best Practices Guide (5697-6731, June 2007)

• portcmd ipperf—Characterizes end-to-end I P path performance between a pair of B-Series
FCIP ports. The path characterization elements include:
• Bandwidth—Total packets and bytes sent. Bytes/second estimate will be maintained as a
weighted average with a 30 second sampling frequency and also as an average rate over the
entire test run.
• Loss—Estimate is based on the number of TCP retransmits (assumption is that the number of
spurious retransmits is m inim al). Loss rate (percentage) is calculated based on the rate of
retransmissions within the last display interval.
• Delay/Round T rip Time (RTT)—TCP smoothed RTT and variance estimate in milliseconds.
• Path MTU (PMTU)—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 limited support for black hole PMTU discovery. If the Jumbo PMTU
(anything over 1500) does not work, ipperf will try 1500 bytes (minimum PMTU supported
for FCIP tunnels). If 1500 PMTU fails, ipperf will give up. There is no support for aging.
PMTU detection is not supported for active tunnels. During black hole PM TU discovery, the
BW, Loss, and PMTU values printed might not be accurate.
• portshow fcipTunnel—Displays performance statistics generated from the WA N analysis.
WAN analysis tools
Typically, you start the WAN tool before setting up a new F CIP tunnel between the two sites. You can
configure and use the ipperf option immediately after installing the IP configuration on the FCIP port.
Once the basic IP addressing and IP connectivity is established between two sites, you ca n 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 to:
• Validate a service provider Service Level Agreement (SLA) throughput, loss, and delay
charac
teristics
• Validate end-to-end PMTU, especially if you are tr ying to eliminate TCP segmentation of large
Fibre Channel frames
• Study the effects and impact FCIP tunnel traffic may have on any other applications sharing
netwo
rk resources
Procedure description
1. A telnet session is used to connect to the local and remote B-Series Routers and define the IP
interface address to use with the GbE ports on each router. If more than one FCIP tunnel is used,
it is necessary to define a local and remote address for each tunnel. This is accomplished using
the FOS command portcfg. These addresses will be routable across the client IP network and
would have been provided from the client IP network administrator.
2. After the IP address interfaces have been defined, the user can verify that the IP addresses are
routable and reachable by using the B-Series FOS command portcmd with the command control
parameter —ping.
3. With routable connection established and tested with the “ping” step, the user will connect to the
remote B-Series router and use the FOS comm and portcmd with the command control parameter
-ipperf to prepare the remote device for the WANTO O LS diagnostic process. This is known as
specifying the sink mode to accept the new connection and is accomplished with the -R parameter
of the ipperf command. There are additional parameters required, including -s and -d,to
specify the ip address of the source and destination router.
4. Next the user returns to the local B -Series router and uses portcmd with the command control
parameter -ipperf to specify the local machine as the source mode to initiate the TCP connection.
Thesourceend-pointgeneratesatraffic stream and reports to the end-to-end IP path characteristics
from this end-point toward the receiver end-point sink. This step is accomplished with the ipperf
command parameter -S. There are additional parameters required including −s and −d to specify
the IP address of the source and destination router, plus a test duration -t (time to run test: default is
forever) and -i (display/refresh interval, default: 30) specified in seconds.
B-Series remote replication solution
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