I am seeing CRC errors on my network
26 10/100 Copper nTAP (7 Feb 2018) — Archive/Non-authoritative version
straight-through cables. If you are using two straight-through cables, replace one
of them with a crossover cable.
I am seeing CRC errors on my network
If you are seeing an uncommonly high number of CRC errors, this could indicate
that there is an issue with the TAP, but it may also indicate that the TAP is fine
and there are other problems on your network. Contact VIAVI
Technical Support
for assistance.
VLAN tags not visible at the analyzer
All TAPs pass VLAN tags with the packets. If you are not seeing the VLAN tags at
the analyzer, check the following:
♦
On the switch:
●
Confirm that the SPAN was created to pass VLAN tags. Sometimes
SPANs are created and passing VLAN tags is not enabled.
●
Confirm the communication between the switch and the router is
passing the VLAN tags (normally the communication between them is
not a trunk).
♦
On a GigaStor, if you are using one:
●
Confirm the capture card has been enabled to receive or pass VLAN
tags.
Memory
Fully optical TAPs do not have internal memory or any electronic components and
are strictly a pass-through wherein a copy of the data is made. TAPs with any
copper connections have two distinct and separate memory stores.
The two memory stores are non-volatile memory and volatile memory. They are
not connected in any way and no data can move between them. The
non-volatile
memory
provides certain functions that make the device work and cannot be
modified or changed during normal operation of the device.
Volatile memory
holds network data as it is copied and passed through the device. Turning off the
device clears any data in the volatile memory buffer.
Maximum frame size
The maximum frame size allowed through an nTAP is up to 16K; 64K super jumbo
frames are not supported.
Understanding why Link B is active when Link A is
offline
Link B is an active port. It is used to negotiate speeds for both Link A and Link B.
Applies to:
Any copper-based nTAP.
When the main use of the nTAP is to monitor a server connection, Link A is for
the server and Link B is for the router or switch. This allows the server to use a
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