Problem while connecting host to 2950G-48

[marcelscheller]

Hello,

Design:

I'm having a 2950G-24-EI switch connected to a 2950G-48-EI using a GBIC type "WS-X3500-XL", the 2950G-24-EI is connected to the "Core" using a GBIC type "WS-G5484. Both switches running IOS Version 12.1(13)EA1

Situation:

A host is using Fa0/1 on the 2959-24, everything is working fine, when I connect the host using Fa0/38 on the 2950-48 only the link status is connected, no mac-address is seen in the mac-address-table. The configuration of both ports is the same. When I connect the host on another switch in the same LAN everything is working fine. Connecting other hosts using Fa0/38 on the 2950G-48 is causing no problems.

We rebooted the 2950G-48, the problem is still occuring. On Friday we will reboot the 2950-24, maybe that would help, but what caused this?

Please any comment

Thanks

Marcel

[ehirsel]

When you state that no mac-address is seen in the mac-address-table, is the table that you refer to on the 48-port or the 24-port 2950G?

If I understand your issue correctly, if you plug in a host on the 24-port cat and then replug that same host into the 48-port cat you have the issue. Is that correct?

Were there any log entries on the host itself that may give a clue as to the issue?

Is autonegotiate being used on the sw ports or are you hardcoding the speed and duplex values?

Are you using the same cat-5 cable to connect various hosts or do you use different cables for different hosts?

[marcelscheller]

Question 1: no mac-address is seen on the 48-port cat.

Question 2: Correct

Question 3: The host indicates an 10Mb half duplex connection but isn't receiving any packets.

Question 4: We've tried auto sensing on the switchport, no effect. here's the running config of the interface:

interface FastEthernet0/38

description 111-31-D7

switchport access vlan 2

switchport mode access

no ip address

duplex half

speed 10

spanning-tree portfast

end

The interface on the 24-port cat has the same config.

Question 5: The cabling stays. I don't believe thats the cause while other hosts succesfully connects to this interface.

Marcel

[Dominique Demore]

Could you provide what the logs are saying?

[marcelscheller]

There isn't any logging available because everything looks fine, i can provide some interface counters but that wil have to wait till tomorrow. I will clear the counters and tray connecting the host again, the counter information i shall post tomorrow.

When you look at the host the only "logging" is the activity of the Lan connection, it indicates only sent activity, no receive activity.

Marcel

[robphill]

do a 'show post' on the 2950G-48-EI and see if there are any POST failures, it is a long shot but maybe there is something wrong with fa0/38 or it's ASIC that is causing this.

[Dominique Demore]

Another item you might want to try is to strip the hardcoded speed and duplex configuration. If you connect the host to another port (ie: fa0/40) do you get the same results?

-- Dominique

[marcelscheller]

We've tried the auto setting, no result. We'll try another interface on the same switch tomorrow.

Thanks

Marcel

[marcelscheller]

sh post: Passed

Nice one isn't it?

Marcel

[marcelscheller]

Hello,

After trying several combinations we've found the problem.

****************************************************

It's a know issue:CSCdz74685

If you configure a static secure MAC address on an interface before enabling port security on the

interface, the same MAC address is allowed on multiple interfaces. If the same MAC address is

added on multiple ports before enabling port security and port security is later enabled on those ports, only the first MAC address can be added to the hardware database. If port security is first

enabled on the interface, the same static MAC address is not allowed on multiple interfaces.

There is no workaround.

****************************************************

We've searched in the wrong direction because the interface thats working fine has no security configured and therefor no mac-address is stored in the running config on that interface. The user connected the LapTop a year ago on an interface with security enabled........ We've removed the mac-address from the interface configuration and everything is working fine!

Thanks for all the comment!

Marcel

Thanks