January 15 2005
What is Ping?
Packet Internet Groper or Ping is a network utility used to
determine whether a particular computer is currently connected to the Internet.
It works by sending a packet to the specified IP address and waiting for a reply.
Ping and Radio Cards
When you Ping and IP address using radio cards the first
signal line which is 0 always gives a higher value if the radio card is
inactive. The radio card in stand by mode. If the card detects network activity
it will wakeup and go to full power.
Seq. line refers to sequence and the time is in
milliseconds. This example show the extra time the radio card require to
wake up. In this example the first line is a bad time but I have seen it
higher that 1000 ms!
64 bytes from 1.x.x.x: icmp_seq=0 ttl=62 time=55.213 ms
64 bytes from 1.x.x.x: icmp_seq=1 ttl=62 time=11.612 ms
64 bytes from 1.x.x.x: icmp_seq=2 ttl=62 time=12.901 ms
64 bytes from 1.x.x.x: icmp_seq=3 ttl=62 time=11.928 ms
64 bytes from 1.x.x.x: icmp_seq=4 ttl=62 time=12.086 ms
64 bytes from 1.x.x.x: icmp_seq=5 ttl=62 time=9.519 ms
Since my network has very few people on it I have to ensure
that the radio cards don't go to sleep. I keep them working 24 hours a day by
issuing a ping command from the last node to the first node . The other nodes
that have more traffic on them do not require this constant wake up call.
As a result of constant pings what actually happens to the
reporting? Well if I don't ping inactive MeshAP the sometimes fail to log
into Wiana.
So what do I actually ping? From the furthest node out I
issue a ping command to the gateway MeshAP.
Ping as a monitor tool
Although Wiana is good monitoring to show topology and
any changes to your node, configuration etc. Waiting for 30
minutes to see if your nodes are up is acceptable for most situation;
however there are times when you need to monitor the nodes on a
continuing basis. There are a number of commercial and shareware
version but if you ssh into your node and issue the command pingtest you
can see all your nodes that are connected and their ping times. If
you issue watch pingtest then you can monitor all your nodes continuously.
