I have a 3845 router direct cabled to an ASA5400. The router was set for duplex auto and speed auto with the ASA set for duplex full and speed 100. With this, the router was showing the connection at 100/half. When I set the router to duplex full and speed 100 the interface went down and would not come back up.
If I set both devices to duplex auto and speed auto, then the router still only comes up to duplex half and speed 100.
I have the ASA set to duplex auto and speed auto, and the router to duplex full and speed 100. This now shows the router at 100/full as well as the ASA.
I thought you should always hard code both devices and not let them auto negotiate.
Why does the connection not work when both are hard coded?
Why does the connection not work the same when the ASA is hard coded and the router set to auto?
This was also true of the inside port of the ASA also going to another 3845 router.
Thanx for the help.