Observer nTAPs : Observer nTAPs : FAQ : Not seeing traffic at the analyzer from the TAP
Not seeing traffic at the analyzer from the TAP
If your TAP is not transmitting to the analyzer as you expect, check the following:
The Link is definitely up and running.
The cable connected to the analyzer functions properly. Use a different cable to confirm this.
The Ethernet/SPAN or Fiber channel is not diverted elsewhere.
Try swapping the cables between the ports.
The nTAP is receiving power using a VIAVI power adapter. The Link A and Link B lights flash when there is traffic traversing through the nTAP, which indicates the nTAP has power.
If you are using a TAP with a GigaStor, ensure the driver configuration speed is set correctly. Sometimes allowing it to auto-negotiate will enable the connection.
If the system you are monitoring is Linux or UNIX based, you may have an issue with the Maximum Transmission Unit size. The TCP stack in the UNIX system uses algorithms to produce an MTU based on response time from SYN ACK. A small MTU forces a server and client to redo their handshake. Increase the MTU on your server to alleviate this issue.