The lltping utility exchanges network traffic over a cluster to test the LLT network connectivity. A host on the network can run an instance of lltping in server mode to reflect packets from the other hosts. An instance of lltping in client mode can then be used to send an echo request to any other host and receive an echo response. If there is no response within 10 seconds (the default timeout period), the client declares that the remote host is not functioning. If the ping succeeds, lltping displays the state of the node and the network links.
Additionally, lltping can be used to report round-trip-time (RTT) between the client and server.
Note: In the client mode, lltping returns 0 if the remote host is alive, 1 if the remote host responds, but one or more network links are down, and 2 or the errno if there is an error. To test your network after configuring LLT on all the nodes in the cluster run lltping in the server mode on the lowest node in the cluster. Run lltping in the client mode on all the other nodes and have them contact the lltping server on the lowest node in the cluster.
The RTT reported is between lltping instances running in user-space on two nodes. Hence the RTT numbers obtained are not indicative of RTT observed by kernel clients (which are the real ones) of LLT. Also timings of first few packets is not taken into account while reporting average RTT. This is because RTT of initial packets include connection setup delays which are a one time phenomenon and should not be part of the average.
Network connectivity check
system1# lltping -s &
system2# lltping -c 0
Node 0 is alive
Node State Link Status Address
0 system1 OPEN
qfe0 UP 00:30:6E:06:81:7B
qfe1 UP 00:30:6E:06:51:CA
system1# lltping -s -T &
system2# lltping -c 0 -T
lltping: send_recv_ping to node=1, pkts=3
lltping: pkt=0, rtt=(0s 161382us)tx=(0s 157us) rx=(0s 161225us)
lltping: pkt=1, rtt=(0s 285us)tx=(0s 131us) rx=(0s 154us)
lltping: pkt=2, rtt=(0s 287us)tx=(0s 133us) rx=(0s 154us)
lltping: pkts=3, msgsz=128, rtt:min/avg/max=285/53984/161382 usec