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New Member

cat 1900, extra mac-addresses, network connection is lost intermittently

Hello !

Could you please help us.

we are having intermittentent network connection losts with ibm 600e laptops with 3com 3c575c 10/100 pcmcia cards ( with or without docking stations).

laptops are windows xp's. switches are 1924 ver V8.01.02 : Standard Edition and 1924 . connections have been tested also with Version V9.00.04 (Enterprise Edition Software without vtp or trunks :only one vlan is used)

But without any improvement to the situation. Problem started after upgrading laptop from nt to xp.

Problem: intermitently twice a day network connection stops working, ping packet loss is 80% . link is not flapping : it stays up. sometimes connections start working after booting 5 times laptop or after one day without doing anything. when there is a problem strange thing happens.

suddenly switch sees several strange mac-addresses in port table ( there are also the actual mac-address)

here are wrong mac-addresses. Lists were taken within one hour when ping packet loss was 80% . The actual mac-address is

0050.048F.6012

ka-6#sh mac-address-table int eth 0/5

Address Dest Interface Type Source Interface List

----------------------------------------------------------------------

B064.5F25.0050 Ethernet 0/5 Dynamic All

0000.0100.0000 Ethernet 0/5 Dynamic All

0001.0005.0013 Ethernet 0/5 Dynamic All

0050.048F.6012 Ethernet 0/5 Dynamic All

3AC8.FF53.6444 Ethernet 0/5 Dynamic All

0000.0000.0000 Ethernet 0/5 Dynamic All

E400.6B00.6100 Ethernet 0/5 Dynamic All

0200.0000.0000 Ethernet 0/5 Dynamic All

ka-6#sh mac-address-table int eth 0/5

Address Dest Interface Type Source Interface List

----------------------------------------------------------------------

7000.7500.6E00 Ethernet 0/5 Dynamic All

0000.0100.0000 Ethernet 0/5 Dynamic All

0050.048F.6012 Ethernet 0/5 Dynamic All

3AC8.FF53.6444 Ethernet 0/5 Dynamic All

0000.0000.0000 Ethernet 0/5 Dynamic All

E400.6B00.6100 Ethernet 0/5 Dynamic All

0200.0000.0000 Ethernet 0/5 Dynamic All

ka-6#sh mac-address-table int eth 0/5

Address Dest Interface Type Source Interface List

----------------------------------------------------------------------

7000.7500.6E00 Ethernet 0/5 Dynamic All

0000.0100.0000 Ethernet 0/5 Dynamic All

0050.048F.6012 Ethernet 0/5 Dynamic All

0000.0000.0000 Ethernet 0/5 Dynamic All

E400.6B00.6100 Ethernet 0/5 Dynamic All

0200.0000.0000 Ethernet 0/5 Dynamic All

ka-6#

ka-6#sh mac-address-table int eth 0/5

Address Dest Interface Type Source Interface List

----------------------------------------------------------------------

7000.7500.6E00 Ethernet 0/5 Dynamic All

7400.6500.2000 Ethernet 0/5 Dynamic All

0050.048F.6012 Ethernet 0/5 Dynamic All

0000.0000.0000 Ethernet 0/5 Dynamic All

0200.0000.0000 Ethernet 0/5 Dynamic All

ka-6#

ka-6#sh mac-address-table int eth 0/5

Address Dest Interface Type Source Interface List

----------------------------------------------------------------------

0000.B86A.1274 Ethernet 0/5 Dynamic All

2002.5801.13FE Ethernet 0/5 Dynamic All

0050.048F.6012 Ethernet 0/5 Dynamic All

ka-6#sh mac-address-table int eth 0/5

Address Dest Interface Type Source Interface List

----------------------------------------------------------------------

0000.B86A.1274 Ethernet 0/5 Dynamic All

2002.5801.13FE Ethernet 0/5 Dynamic All

0050.048F.6012 Ethernet 0/5 Dynamic All

0000.0000.0000 Ethernet 0/5 Dynamic All

Any help is appreciated !

TIA

Best Regards,

Susanna U

5 REPLIES
Purple

Re: cat 1900, extra mac-addresses, network connection is lost in

Make sure switch ports are set for 10/half , the 1900's have no auto negotiation ability , then make sure all laptops are set as auto so the speed and duplex match up . Because the 1900's have no auto ability the laptop will see this and default to 10/half as speed can be autosensed . If you stick a laptop that has been hardcoded to say 100/full this could cause all kinds of problems . You cannot set the 1900 ports to 10/full unless you plan on hardcoding all your laptops to 10/full instead of auto as this will cause speed duplex mismatches and poor performance on your switch ports . Other possibility is someone a couple of times a day is hogging all the bandwidth , you could clear the counters and see if anyone is passing large amounts of data while this is going on , if your uplinks are only 10/half then this may be what's happening .

New Member

Re: cat 1900, extra mac-addresses, network connection is lost in

Thank you for you answer. but i dont think duuplex-setting is the issue.

we have 10/half switches and auto-mode in ibm 600e's.

there are about 10 out of 30 laptops that lose connections approximately once a day. desktop computers do not lose connection, neither do other models of laptop.

Can you say anything about the strange mac-addresses ? where do they come from ?

TIA

Best Regrads

Susanna

New Member

Re: cat 1900, extra mac-addresses, network connection is lost in

Dear Susanna,

I saw something like this threetimes but it was never caused by Catalyst.

One of ours pc's insist on four MAC addresses:

> Catalyst 1900 - Port 16 Addressing

>

> Dynamic addresses: 0 Static addresses: 4

>

> Type Address Accepted source ports

> Static 00-00-00-01-B4-9D Unrestricted

> Static 00-00-00-E0-B4-9D Unrestricted

> Static 00-00-00-00-B4-9D Unrestricted

> Static 00-00-B4-9D-FB-AC Unrestricted

>

It has two NIC's but it does not entitled it to have four MAC which seems to be derived from the regular one (last line). Obviously NIC's failure.

Once I saw a network breakdown due to changing MAC addresses caused by a new W2000 server which was attempting to build a cluster from all pc's with W2000 od XP.

At last I saw changing addresses caused by a virus.

The issue is very probably in configuration (or HW?) those 10 pc's.

Regards,

Tom

Re: cat 1900, extra mac-addresses, network connection is lost in

Are you sure you have the right Ethernet driver for the IBM? We had a similar issue before, where the IBM's individually seemed to be OK, but they were all showing up with the same MAC address - turns out there are multiple Ethernet drivers that SEEM TO WORK on them, but some pick up a bogus MAC address, possibly from the firmware on the Ethernet card.

New Member

Re: cat 1900, extra mac-addresses, network connection is lost in

Thank you for your answer !

It seems it must be a network card and/or driver problem.

We changed one of the laptop's network-card to another model and problems went away.

need to test this with other laptos that have the same problem

Best Rgds,

Susanna

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