spanning tree on Catalyst 2900 XL

[sebjenkins]

Hi,

We have machines and printers that disappear and reappear on our AppleTalk network.
I understand that this is related to Spanning Tree and/or Portfast ?

Does Spanning Tree need to be disabled ?
Does Portfast need to be enabled ?

We have several Catalyst 2900 XL switches in our rack.

Is config of the switches done using a crossover cable and Hyperterminal ?

Any help would be much appreciated !

 

[wybnormal]

Spanning tree keeps data loops from forming if there are multiple paths to given switches.

SW1----------SW2
SW1----------SW2

One link will be "blocked" and the other is "forwarding". If the forwarding links goes down, the blocked port will take over after roughly 50 seconds. (old Spanning Tree, the new version is VERY fast)

Portfast allows spanning tree to skip a couple of steps and go straight into forwarding mode. This ASSUMES that the device on the other end is a workstation or server or anything other then another switch. It is possible for spanning tree to give you headaches if end devices are plugged directly into the core and then turned on and off all the time. Each time, spanning tree has to recalc if the port needs to be blocked, if it's root port, etc..etc. Normally it is just messy. But sometimes a fast system can come up before the port is ready and that can cause problems. Especially since by the time you get to it, the port is up and everything "looks" fine. Hence the use of Portfast.

Your switches can be configured by a console cable or just by telneting to the switch IP address (assuming one is configured)

Portfast notes:

http://www.cisco.com/warp/public/473/12.html

MikeS

Find me at

http://www.packetattack.com

"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu

 

[sebjenkins]

Hi,

Thanks for the info.

I have connected the blue flat cable (RJ45->9 pin dtype) from the console port on the Catalyst to the com port on my PC.

I started up Hyperterminal and setup the port no. to use and the baud rate to 9600,8 databits, flow control xon / xoff and parity none and stop bits: 1 but I can't get anything up in the terminal window.

Am I doing something wrong ? Does the switch need to be rebooted for the PC to see it through Hypertrm ?

 

[vipergg]

No you should not have to reset the switch , if its not working then its the cable or your hyperterm is not correct.

 

[sebjenkins]

Tried correct cable but can't get any output to the terminal window on the Windows PC.
Have connected the Cisco blue flat cable to both com ports 1 & 2 but no joy.

On Friday,when I recoonected the cable to one of the swithes I got entried in my terminal window but when I connected the cable to another switch I got nothing so I connected it back to the previous switch and once again, but this time nothing. I'm very confused!

 

[sebjenkins]

O.k. I now have a SWITCH command prompt in my HyperTerm window.

SO to recap, I have an issue with spanning tree which caused probems to my AppleTalk network.

Do I disable spanning tree and be done with it or do you do this AND enable portfast ?
Also these swicthes and daisy chained to each other so I understand that spanning tree had to be be kept on the for the port that it uplinking etc ??

please provide command line info too PLEASE!

tHANKS IN ADVANCE

 

[sebjenkins]

Thanks for your help. All sorted now. The original problem of not getting output to Hyperterm was resolved by attaching the console cable to the comport on my laptop instead of the desktop PC.

Then from the SWITCH command I assigned IP addresses and accessed them from web admin and turned off spanning tree there. Now my AppleTalk network is alot more snappier and responsive!