Router - TG582N - Monitoring an Ethernet Port

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Sometimes it's useful to be able to monitor traffic on an Ethernet port of the TG582n (e.g. the attached device is a VoIP phone and one can't run Wireshark on it).

Many of the Technicolor routers (including the TG582n) have the useful facility to take the traffic flowing on one Ethernet port and monitor it on another Ethernet port. The CLI commands needed are:

Declare the port to send the monitor traffic to. In this example, it will be sent to port 2:

:eth switch mirror capture port=2

Now declare which traffic on which port to monitor. In this example, we'll monitor inbound and outbound traffic on port 4:

:eth switch mirror ingress port=4 state=enabled
:eth switch mirror egress port=4 state=enabled

It is still possible to use the capture port (port 2 in the above example) as a normal Ethernet port, just that Wireshark (or similar) will see both normal traffic and the monitor traffic - so get your capture/display filters sorted out.

It doesn't seem possible to discover the current settings of the monitor, so when finished it might be best to issue:

:eth switch mirror ingress port=4 state=disabled
:eth switch mirror egress port=4 state=disabled

Monitoring a PPPoE link

It's possible to use this facility to monitor the traffic flowing on a PPPoE link (i.e. outside the firewall) on one of the router ports. However the wanted traffic may be swamped by the AAISP CQM packets. In this case, a capture filter to discard the PPP LCP packets will be helpful. For libpcap applications, this is:

pppoes and not ppp proto 0xc021

Other pages regarding this router

<ncl style=bullet maxdepth=5 headings=bullet headstart=2 showcats=1 showarts=1 showfirst=1>Category:Router TG582N</ncl>