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Troubleshooting common issues
358 GigaStor (23 Feb 2018) — Archive/Non-authoritative version
Size Distribution Statistics, Top Talkers –MAC (by hardware Address) will now
show data by Port.
Suspected NAT or VPN issues
If you use network address translation (NAT) in your environment, you must
make some configuration changes in Observer. Using the TCP/IP port information
in Ports used by Observer products v16 and earlier (page 212) , you should be able
to set up the NAT properly.
If the probe is outside the network where Observer is running, you must forward
port 25901 from the probe’s address to the system running Observer.
When redirecting the probe, you must specify the NAT outside IP address instead
of the address that Observer puts in automatically. By default, Observer tries to
use its local IP address, which the probe will not be able to find. Select “Redirect
to a specified IP address” in the Redirecting Probe or Probe Instance dialog and
type the VPN client’s IP address.
Running Observer passively affects NetFlow
When analyzing a link using a TAP, which is common, Observer runs “passively.”
Passive operation guarantees that analysis will not affect the link; however, it
does have some implications when running NetFlow. Because there is no link
over which the system can transmit packets or frames, the following features are
unavailable:
♦
Traffic Generation
♦
Collision Test
♦
Replay Packet Capture
Daylight Savings Time
Observer is not coded with a specific date in mind. Daylight Savings Time is
controlled by the operating system. When the clock rolls backwards or forwards
Observer rolls with it, with one exception: packet capture/decode.
Packet capture provides nanosecond time resolution, which none of the rest of
the product does. Because of this, packet capture does not rely on the system
clock to provide time stamps. It relies on the processor time ticks. When Observer
opens it requests the system time and the number of processor time ticks and
uses those. This allows Observer to know what date and time it is when a packet
is seen.
Because the Observer only asks the operating system for the system time when
Observer is started, packet capture does not know that the time has jumped
forward or backward. To get this to happen you need restart Observer after the
time change. It is that simple.
Configuring Cisco 6xxx switches using a SPAN port to a full-
duplex Gigabit Probe
When using a full-duplex Gigabit Probe to capture directly from a SPAN/mirror
port, use a straight-through cable from the Gigabit port on the switch to either
port A or B on the Gigabit card in the probe. Do not use the Y-cable or TAP (the
TAP and Y-cable should only be used inline).