Re: Cisco Catalyst 2960L-48TS-LL hangs and LEDs stop working

david · ‎01-04-2019

I had this issue several times now. All of a sudden all 48 port LEDs stop flashing and does not change when I plug in/out cables. The computer says the cable is connected but with an unspecified network, just like it doesn't get an IP. Plug out the power and reboot brings the switch back online again. Last time it happened just 1 day after the previous event. The switch still works though but can't connect any new hardware to it and the network does not work when booting up a computer that has been offline.

Is it faulty hardware or can it be overloaded somehow? We make a lot of backup during night time and it has been in the morning I've seen the problem.

The switch is not in managed mode, so can't really check any logs. That is a serious issue in itself because the default IP of the switch is 10.0.0.1 which is the same as our main firewall and it would be a tremendous amount of work to change that. I worked a whole day trying to change the default switch IP but closest was to setup an additional IP, not change the default colliding one. From what I could gather from the Internet this switch is not a "real" layer3 switch which prevents me from doing that. I found some commands how to do it but they did not work. I mean come on, even the most basic of network devices have an option to change IP..

Andrew Khalil · ‎01-04-2019

Hello David,

Greetings,

Actually, you don't need to configure an IP for the switch to monitor the logs, you can just connect your PC to the Switch's console port through a console cable and using a terminal software on your PC like Putty which is a freeware!

To configure an IP address to a layer 2 switch for the management purpose, you can configure it on the SVI (switch virtual interface) which is an IP address for any created vlan, to achieve that:

create any vlan like:

#enable

#config ter

#vlan 10

#interface vlan 10

#ip add 10.1.1.1 255.255.255.0

#exit

or any other IP address like what you want!

Your PC must be in the same vlan to be able to ping it or reach it, to do so:

connect your pc with any port of the SW for example port f0/1

then configure the following:

#interface f0/1

#switchport mode access

#switchport access vlan 10

#no shutdown

#exit

but you can not anyway open the switch through telnet for example, except when you enable the vty line and to create at least enable password, to do so:

#enable password 12345

#line vty 0 4

#login

#exit

Now, it's done, you just need to give your PC an IP from the same range of the interface vlan 10 IP (10.1.1.1) for example 10.1.1.2 255.255.255.0, and you don't need a gateway!

then you can ping from your PC the switch! or even telnet it!

I don't know whether I understood your post correctly or not, that's why I don't understand why you can not telnet the switch except that your firewall has the same IP, if it's so, you can just disconnect the cable of the firewall from the switch, and at this moment there will not be any IP address conflict, and you can reach the switch with telnet and change the IP like how I explained above and reconnect the firewall back!

Also when you get the logs, let us know it, may be we can interpret the reason of your main problem!

I hope my reply is helpful enough to solve your problem!

Please don't forget to rate my reply if it's helpful, and to mark it as a solution if it's helping to solve your issues!

Thanks in advance!

Bst Rgds,

Andrew Khalil

david · ‎01-04-2019

Thanks for the info, I will try this. I need to know:

Where do I get a consol cable (that works with this switch)?
Do I need to set an IP to get the logs or can I use the consol cable?
How do I get the logs?

Andrew Khalil · ‎01-04-2019

Hello David,

Greetings,

As I said, you don't need at all to configure IP address if you have access to the switch directly through the console cable!

Also, logs appear alone on the terminal software window once you access the switch.

Finally here is some online links of the console cable, they are standard and works with all the models!

Note that you can buy it from any online store you would like, they are all the same, here is just as an example, but I am not meaning to advertise the seller or even to grantee the seller's trust!

Also, for your kind info., usually the console cable is coming with switch when you buy it so you can search about it if it's possible, but in case of losing it, you should buy it, you can find it online, here is links:

1- This one looks like the original one, but you must have a serial port in your PC, if not, you will need to buy adapter to convert it to USB!

https://www.amazon.com/dp/B07HKKMYMF/ref=sspa_dk_detail_2?psc=1&pd_rd_i=B07HKKMYMF

2- Which I use all time and prefer:

https://www.amazon.com/Tekit-Cisco-Router-Console-Cable/dp/B07CV6RSW9/ref=sr_1_5?ie=UTF8&qid=1546607526&sr=8-5&keywords=cisco+console+cable

I hope my replies help you enough so that I can get your helpful rating! also, please mark my reply as a solution if it's helping to solve your issues!

Thanks in advance!

Andrew Khalil

david · ‎02-04-2019

I got the cable and can connect with putty now. It froze yesterday for the first time in weeks and I could see today that not even serial console respond when the switch is in that stage.

Anyway, after a reboot I could successfully do the initial setup from the console and could choose an IP other than 10.0.0.1 so no more conflict with firewall. The initial setup via web interface I did last time was crap. So at least now I have log files I can check next time it happens and maybe the initial setup did something good hopefully. The switch was unconfigured before.