One of my cisco 3550 switchport (fastEthernet)is connected to an ASA firewal gig port. Settings are as follows:
@Switch: Full duplex / 100 mbps
@FW: auto / auto
Now the problem is that the FW interface is negotiating to half duplex / 100 mbps rather that full duplex. Where does the problem lie, we want it to be ful duplex? can a bad cable or bad port also create such duplex mismatch.
you will find that if you have a duplex mismatch on two cisco devices that support CDP you will get messages stating that there is a duplex mis-match right away (FW probably doesn't have cdp on by default) this is because Cisco can read both sides of the connection and tell if there is a mis-match. not sure that I want a message popping up every time I hard code a speed/duplex.