Currently, I have both sides set to auto and the speed and duplex are 100full on both end.

this is seriuos stuff... again, when I manually set both ends at 100full, it does not work.

My switch is a 2950. I've read that there might be cases where some settings on the switch ports are turned on by default and these might affect or conflict when the switch ports connects to an ASA. For example, the channeling, the trunk mode, etc., are features that might be on by default on a switchport.

any help

Can you post the conf of the switch interface? Also turn your logging on the switch to debug, then configure both to 100/full, and then connect the cable and post the log.

Yeah we do need to see the config, but if both ends are connecting at 100mb full duplex -auto, then you aren't gaining anything by hard setting it anyway.

you're right, but then you get that itching thing that when something is supposed to work and it doesnt... plus, it is always better to hard-code those things anyway, I believe you do gain some speed (in terms of seconds)...

here's the port config:

interface FastEthernet0/16

switchport mode trunk

spanning-tree portfast trunk

end

here's the sh ver:

3#sh ver

Cisco Internetwork Operating System Software

IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(22)EA4, RELEASE SOFTWARE (fc1)

Copyright (c) 1986-2005 by cisco Systems, Inc.

Compiled Wed 23-Mar-05 15:33 by yenanh

Image text-base: 0x80010000, data-base: 0x80562000

ROM: Bootstrap program is C2950 boot loader

INSC2950-03 uptime is 51 weeks, 1 day, 16 hours, 44 minutes

System returned to ROM by power-on

System image file is "flash:/c2950-i6q4l2-mz.121-22.EA4.bin"

cisco WS-C2950SX-24 (RC32300) processor (revision L0) with 21039K bytes of memor y.

Processor board ID FHK0937W0M9

Last reset from system-reset

Running Standard Image

24 FastEthernet/IEEE 802.3 interface(s)

2 Gigabit Ethernet/IEEE 802.3 interface(s)

32K bytes of flash-simulated non-volatile configuration memory.

Base ethernet MAC Address: 00:15:63:8C:C3:C0

Motherboard assembly number: 73-8135-07

Power supply part number: 34-0965-01

Motherboard serial number: FOC09370NRP

Power supply serial number: DAB0924BQTM

Model revision number: L0

Motherboard revision number: A0

Model number: WS-C2950SX-24

System serial number: FHK0937W0M9

Configuration register is 0xF

The port is now setup as a trunk as I had to create sub-interfaces on the ASA.

For the logging part, this is what I have on the switch:

logging buffered 512000 debugging

I think I had the console up when I was doing this last night and every time it was failing, nothing was coming up on the switch... no logs... but perhaps I need to increase the logging, I don't know... HELP

Your logging looks OK, but you should have seen some entries on why it was not connecting. Have you enabled logging as well (logging enable)?

Did you solve this? I'm having the same issue.

I never got or found a definite answer. I gave up and kept them to auto.

Since, didnt have the time to troubleshoot any longer as it is a production environment.

There has to be an answer though. The other day, I was presented with the same scenarion, and I was remotely doing the work, so in order to be on the safe side, I didnt even bother to follow best practices (hard coding the ports) and kept the asa and the 2950 switch on auto

didnt really want to risk it

Check with cross over cable or straight cable ,if your using cross over. pl check in  non production hour ,it should be ok .

-MK