How many ethernet card can go into a 3640 series router?

[j-bliss]

I know that a 3640 will only support 2 Fast Ethernet interfaces but how many ethernet interfaces is the max?

[Prashanth Krishnappa]

3640 has 4 slots. And we have NM-4E which is a 4 port ethernet module and so you can have 4 of these giving you 16 ethernet interfaces. You might also want to look at the 16-Port EtherSwitch Network Module

http://www.cisco.com/warp/public/cc/pd/rt/2600/prodlit/16prt_ds.htm