Cisco switch is pissing me off

[Kelemvor]

I have a Cisco 2950 that was getting tossed at work so I rescued it. I'm trying tog et it setup on my home network and am having trouble. It's a 12-port switch.

My setup is Cable Modem -> SMC Router (handling DHCP) -> Cisco 2950 -> PCs

Problem is, any time the Cisco switch is powered on and connected, it just kills the rest of my network and everything goes to crap. At work we just plugged a cable from the wall jack into port 1 on the switch and plugged a PC into some other port and everything was fine. No idea why it's not working any more.

I'm reset the settings manually and shouldn't need to actually program anything since I just want it to work like any plain, old hub/switch would.

I've tried a cross-over cable and a regular cable and neither work. Then even if I have a PC plugged directly into the SMC router, it still gets crap for the internet if the Cisco switch is even connected. SOon as I pull the plug on it, everything starts working fine. Seems really strange to me.

Also it shouoldn't be hardware related as the switch was barely ever used and is basically brand new.

Any ideas?

Thanks!
Thanks.

 

[skyking]

Does the switch have an IP? Could it have the gateway IP for the management interface?
That right there would bork the internet bad.
Maybe it has some different subnet for the management interface, and that is somehow causing the problem.

 

[Kelemvor]

I ran the Quick Setup thing and gave it an IP on my normal range and put in the gateway of my main router. That's all it asked for. Plugged it in and everything just went to crap. I slapped in my 9port Netgear Hub and that's working just fine. I guess I'll just play with this thing whenever I find some freetime. heh.

 

[bruceb]

Here is a link to the deployment guide from Cisco for how to set up the switch:

http://www.cisco.com/en/US/products/sw/...ser_guide_chapter09186a008015b87b.html

 

[nweaver]

console in, check the counters (reset and track) on your uplink. I would guess a duplex mismatch on your uplink port. Keep you console connected and it will usually tell you the problem.

Duplex mismatches may be said on the console, but you can look for errors on the counters for the interface (show int fa0/1)

 

[Kelemvor]

Originally posted by: nweaver
console in, check the counters (reset and track) on your uplink. I would guess a duplex mismatch on your uplink port. Keep you console connected and it will usually tell you the problem.

Duplex mismatches may be said on the console, but you can look for errors on the counters for the interface (show int fa0/1)

I've never actually consoled into a switch before. Do I need their software for that? And do I just plug a normal Cat5 cable from my laptop's jack to the COnsole jack and that's it?

 

[Cooky]

For the console port you need a rolled cable going from the serial port of your PC to the console port of the switch.
No extra software is needed besides hyper terminal or any other software you use of telnet/serial connections.

Usually you want to hardcode uplink ports on both sides to be sure everything matches w/o duplex or speed mismatch.
The switch is loud and I wouldn't want it in my home (unless you set it up in your basement or lab purpose.)

 

[Kelemvor]

Hmm. Don't think I have the cable needed to console in I guess. I'll have to see if someone has one at work. And yes, this woudl be in the basement so the loud fan and such wouldn't be any big deal. This was more of just a thing to do for the coolness factor so I'll probably just put it on the back burner.

But thanks for all the info.

 

[spidey07]

If the switch was reset to factory then it will pick up a DHCP address (although I dont' know how you cleared the configruation if you don't know how to console into it...you need a console or telnet to do it), just check the DHCP table and match up the MAC address of the switch. From there you can telnet into the switch.

If you want to truly reset the configuration...

write erase
reload

The only thing of if you plug the switch in and you lose communication, that makes me thing of a loop somewhere. make sure you have no loops.

Also, you can't really just take a cisco switch and not do any configuration. There are certain things that need to be done. Mainly spanning-tree related.

Are you saying that if you just plug the 2950 with a single connection only you have communication problems? I don't know if the 2950 does layer3 switching, but it could be proxy arping for your clients if you have any routing enabled on it. post the configuration of the switch by telneting into it. Or on the off shoot it has the same address as your router.

 

[nweaver]

2950's don't do L3

reset the config. If you can't get enabled mode, then reset from bootup (hold the buttom, flash_init, del flash:\config.txt, blah blah blah)

 

[spidey07]

heh, thanks.

I've never touched a 2950. I just "assumed" all their switches do L3 nowadays.

 

[saabman]

IIRC, the serial cable I purchased everytime I needed a network console cable was actually a DB9 mouse extension cable for a couple bucks. They were always cheaper because they didn't have the network name on them.