The 4230 only has a 10/100 MB port for monitoring.
So it is not a good choice.
Technically, however, you could span a Gigabit port on a switch to the 10/100 MB port that the 4230 is monitoring. As long as there is less than 100MB being transmitted on your Gig port you may be able to monitor it. BUT I usually do not recommend this and even advise against it because of the dropped packets that can result.
If you want to monitor using a Gig port on the sensor then you will need a sensor that supports a Gig port for monitoring (4235, 4250-TX, 4250-SX, and 4250-XL)
Then considered the amount of traffic that will be monitored through that Gig port.
The 4235 can monitor around 250MB through it's copper Gig interface.
The 4250-TX can monitor around 500MB through it's copper Gig interface.
The 4250-SX can monitor around 500MB through it's fiber Gig interface.
The 4250-XL can monitor around 1 Gig through it's 2 fiber Gig interfaces.
NOTE: The 1 Gig monitoring capability of the IDS-4250-XL is aggregate bandwidth of both interfaces.
For example you could monitor
1 Gig on one and 0MB on the other,
or 750 MB on one and 250MB on the other,
or 500 MB on one and 500MB on the other.
