SLM2048 Dropping Connections

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Mar 9th, 2010
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I have a problem with 6 SLM2048 (and 2024) switches we purchased last year.  At first they seemed to work fine, but now I'm rebooting them about once a week at minimum. The problem is that ports start going dead.  An affected computer will sometimes still be able to ping other machines, but no other traffic is allowed through. Rebooting the computer, giving it a new IP, new cables, etc. doesn't work.  Rebooting the switch usually works for about a week or so, then ports start going dead again and another reboot is needed.

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rainbowsystems Thu, 03/25/2010 - 23:04
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we had the same situation. SLM2048 with Firmware 1.0.1

I noticed that HP ThinClients get now IP Adress from DHCP Server. Also fix IP does not work.But networkcard showed connected. I first investige the servers i ven analysed the networkcableing with an electrical specialist.

Power off the switch helped for somedays.

No i was in the forum and decided to upgrade the Firmwar to version the latest.

the switch was rebooted from http upgrade.

The switch is working , but now i can´t log in again. It says wrong password.

regards Thomas

rainbowsystems Thu, 03/25/2010 - 23:08
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i just read in another posting . try admin admin like after a reset .

now i can log in the switch.

why is such an information not included in the firmware upgrade readme file ????

have a nice day


jackson.brunsting Fri, 03/26/2010 - 12:26
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Yeah, that was one of the combinations I tried, but still no luck.  I think I'm going to have to take some time and call Linksys tech support.

rainbowsystems Sat, 03/27/2010 - 02:27
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I have problems to log in with firefox 3.6.2 . I instead used IE8 and put the WEB URL of the switch to the secure sites.

there are problems with IE8 with older Firmware. the new Firmware 2.0.08 is running with IE8 and Firefox.

So I would try also IE6 or & or maybe opera...

Good Luck


jackson.brunsting Mon, 03/29/2010 - 07:26
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I can get to the page fine, no problems.  My real problem is the ports going dead after a while.  I've read some pages that state this might be due to cheap Chinese parts being used inside some of these switches.  They're liquid in nature and when they heat up, they swell and lose contact.  I'm wondering if that could be the case for me.

mschultz Thu, 04/15/2010 - 07:41
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Join the Club.

We purchased 4 of these switches at the end of 2009 and they just seem to drop ports offline.

Nothing resolves the issue until you reboot the switch, then the ports come back online again. Its almost like an "ERRDIS" state on a Cisco switch, but shutting the port off and back on does NOT clear the condition. I don't think this is related to components or it would manifest itself more randomly, I think its either a design issue with the hardware itself or a software issue with the IOS.

I would try the new IOS which they just released recently. Its version

I have the same exact issues with one we purchased a few months ago.  After a few days of being online, any large amount of traffic on the switch will cause it to start dropping packets like crazy - our up/down network monitor go nuts with timeouts.

After this happens, attempting to connect any new devices to the switch fails.  The lights light up on the switch, but in the GUI the port is inactive and although the machine connected can tell there is a link, no data will pass through the port.  This situation can be resolved by rebooting the switch (terrible solution).

Definitely not ever buying or recommending these again - go for the real Cisco stuff, or choose another brand...

jackson.brunsting Tue, 04/20/2010 - 12:34
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Yeah, I'm looking at replacing a large number of smaller switches in the next few months and I had someone recommend some more of these small Linksys/Cisco switches to me.  I told them to forget it, I'll be checking out HP or 3Com if I can't shell out the cash for an actual Cisco product.  I'm more than little unhappy with these switches, and it appears I'm still having the same issues even after calling Cisco support and them being very nice and sending me all "new" switches.  One of them was new, the other 4 were refurbs, and of those, at least one was older hardware than everything I'd just sent back to them.  As I said, it doesn't appear to have helped, though.  Tons of dropped packets on my network, my monitoring software watches stuff bounce up and down all day long.

mschultz Wed, 05/05/2010 - 00:20
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I worked for HP in Network Support for 10 years and HP switches are pretty darn reliable and have a lifetime warranty.

They are not Cisco and their applications are not as diverse, but I have seen HP switches sit and run without any problems for 2-3 years between reboots.

I really like these SLM units in features and pricing, but they need to get this port issue resolved. A unreliable switch is a plague on humanity, and causes endless sleepless nights. If these are just sitting in a closet servicing user PC's you can get away with a reboot in the middle of the night. We had them connected to servers that are up 24 x 7 and rebooting a switch is not something you just do randomly when you have an issue. I have to clear a switch reboot with our Change Control process and it takes days to get permission from all parties involved.

We yanked them out and replaced them with Cisco 48 port units that we had freed up from a previous project.

rainbowsystems Tue, 04/27/2010 - 06:44
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Hello i´m back !

It seemed all was ok after upgrading to firmware but the error came back to soon.

I have more dead ports then before. Only the power off mehtod brings the ports back to life.

Also we notice that the performance while copying files across the LAN was very very slow.

In the Management console Overview the Port is shown as grey colored. But I can manage this port by right clicking. I can change some items but the port does not come back. No data is transported...

I no will give Cisco a Service request...

regards Thomas

Jungo_IEC Fri, 04/30/2010 - 13:47
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Wow. This is an awesome post. I bought one of this babies 2 weeks ago. I got this issue since last week. At first I was thinking that probably it was a PC connected to that port, but after reading this post definitively it's a switch issue. It already came with Firmware version .  This is my very first experiece with Cisco and sadly it was not a good one. So I'm pointing to a full refund. Hope this issue could be fixed since I really like the management GUI of this baby.

Thanks for sharing all your comments.

rainbowsystems Sat, 05/01/2010 - 00:41
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i had an telephone call with CISCO Support last week. The guy confirmed he had heard some issues with the SLM2048 .

I´m very angry, usually we use the srw versions. never we had such trouble . I hope Cisco comes back to me with some "good" news soon.                                               

i´ll keep you informed....


jmwebcanada Wed, 06/30/2010 - 09:11
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I think I may be experiencing exactly the same thing as these other posters, using firmware C
isco, where are you? This must be a known issue given the number of posts about it. Fix it. Get us some firmware that works.

rainbowsystems Wed, 06/30/2010 - 14:45
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Hello !

a guy from Cisco wrote me that  there is a official BUG described under CSCtg30340.

He has no further details but a workaround for these issue :

If you do not have redundancy between two or more switches you should disable STP.

And enable on all Ports with connected networkdevices "portfast"

I did so and have no trouble in this network since mid of May. I hope this helps me to calm down my customer.

I´m not happy about the support. If there is a known issue Cisco should call back those buggy switches.

For me my decission is taken. We now use HP Switches.

hope you will be lucky with this workaround

regards Thomas

vonhirsch Sun, 08/08/2010 - 12:49
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I wish I checked here before buying these plagued switches.

I upgraded from 1.0.1 to and was suprised that my login didn't work admin/admin did work.  One of the switches, keeps blink SYSTEM.  I will research that later.  For me the upgrade was worse than the problem.  Because I lost control of my network and with a switch down, crippled it.  It seems that Cisco is not what they used to be.  Pullin' the rip cord!

jbrunsting Mon, 09/13/2010 - 12:16
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I hadn't looked back at this thread in a while, but was interested to hear this. My replacement switches are also needing reboots now.  One of them I need to reboot weekly.  I've now tried putting in the workaround you were given. We'll see over the next couple of weeks if it helps.

aquar01kimo Sun, 10/24/2010 - 19:23
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I have 10 SLM2048 equipments about 1 year.  Looking for solution to solve the same problems.

Can it solve the problem as you said befor to "disable STP and enable on all Ports with connected network devices "portfast""

Recently, my department is going to buy 11 new products. Should i strongly recommend my department excluding the SLM2048 as considered?

rainbowsystems Sun, 10/24/2010 - 23:28
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we have several SLM at customer and had had all the trouble in the LAN . with deactivating the STP functions the switches now work without any issues.

I don not buy any cisco switches anymore. Linksys / Cisco had a good name but it is very disappointing that kind of quality. HP and now with 3COM are a very good alternative...

Other big probelem we have par example the NSS4000 / 6000  stops working in the LAN. The do not answer a ping and a cold reset is neede. often than 2 time a month...

and cisco is not willing / able to clear that problem.

So we are responsible for that in the customers eye and tha nobody could afford....

regardsa Thomas

nimusell Sun, 03/13/2011 - 00:15
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Hi all,

Thank you very much for participating in the Small Business Support Community. My name is Nico Muselle from Cisco Sofia STAC.

Cisco recognizes that there indeed is a problem with the SLM2048 switches and ports going down and as mentioned earlier in this thread, an official bug has been opened for it. However, the switch development team has been fully consumed with the development for the release of the new Nikola switches (Sx100, Sx200 and Sx300 series) leaving very little time for bugfixes for "older" switches. As the development resources are limited, choices had to be made.

On the other hand, the workaround mentioned here definitely is a valid one. Disabling STP completely where not necessary, or setting port STP mode to portfast where possible makes sure that the switches work as expected, without ports going down.

If you would be concerned about disabling STP if your switches are not physically secured and someone could "by accident" create a loop, you could prevent this by implementing port security so that the port shuts down if another MAC address is detected. This is always a good practice to enhance your network security and avoid problems. If your network requires STP for redundancy, put all the ports not connecting to another switch in portfast mode.

I can assure you that Cisco does care about it's customers and about this problem, and if you would need any help on configuring your switches in such a way that they do keep working in your network, please do not hesitate to contact me or raise a ticket with your local support center referring to this thread.

Best regards,

Nico Muselle

Sr. Network Engineer - CCNA


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