?
Solved

Can't set command "spanning-tree mode rapid-pvst" on catalyst 2950

Posted on 2006-07-02
7
Medium Priority
?
1,964 Views
Last Modified: 2012-08-13
Hi Guys

I have a catalyst 2950 switch set up, when i telnet into it and try to set the command "spanning-tree mode rapid-pvst" i lose connection to the switch.

ie (commands i enter):

config t
spanning-tree mode rapid-pvst

Any ideas why???
0
Comment
Question by:jamewang
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
7 Comments
 
LVL 9

Accepted Solution

by:
jfrady earned 672 total points
ID: 17028573
Does your connection come back?  My suspicion is that what you are seeing is a spanning tree converge.  Traffic is being blocked until a new root bridge is elected and the tree calculated.
0
 
LVL 1

Expert Comment

by:conrad_ray
ID: 17028612
Hi

The command reference says...

Caution: Changing spanning-tree modes can disrupt traffic because all spanning-tree instances are stopped for the previous mode and restarted in the new mode.

spanning-tree mode:
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12122ea7/cr/cli2.htm#wp3076679

Command specifics are always described in the command references for your catalyst switch and ios version. The main link is www.cisco.com/univercd

Conrad.
0
 

Author Comment

by:jamewang
ID: 17028742
Ok....

So currently i have the following option set on the interface fa0/24 which is the interface i use to telnet into the switch:

 spanning-tree portfast
 spanning-tree bpdufilter enable


Is there a conflicting command somewhere
0
 
LVL 1

Assisted Solution

by:conrad_ray
conrad_ray earned 664 total points
ID: 17029796
Hi

Portfast and BPDUfilter are considered best practice configs on end user switchports where we do not expect a switch to be connected - only end user PCs/devices. So this config is not conflicting with what we are discussing here.

The reason your connection gets disrupted when you change the STP mode is, as mentioned earlier, due to all STP instances being stopped for the previous mode (say PVST+), and getting restarted for the new mode (rapid-pvst+), hence reconverging.

Conrad.
0
 
LVL 5

Assisted Solution

by:skaap2k
skaap2k earned 664 total points
ID: 17029984
it's just like conrad_ray says, the topology is busy converging, ports are in LISTENING/LEARNING mode... This should take around 20-30seconds before they'll go into FORWARDING mode, at which point, you should be able to reconnect to the switch,

if you cant, perhaps you have a bridge-loop on your network and that port may be blocked, doing a sh spanning-tree blockedports might help you figure that out too. (using a console cable!)

Kind Regards,
Rob
0

Featured Post

Nothing ever in the clear!

This technical paper will help you implement VMware’s VM encryption as well as implement Veeam encryption which together will achieve the nothing ever in the clear goal. If a bad guy steals VMs, backups or traffic they get nothing.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Short answer to this question: there is no effective WiFi manager in iOS devices as seen in Windows WiFi or Macbook OSx WiFi management, but this article will try and provide some amicable solutions to better suite your needs.
When you try to share a printer , you may receive one of the following error messages. Error message when you use the Add Printer Wizard to share a printer: Windows could not share your printer. Operation could not be completed (Error 0x000006…
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.
Here's a very brief overview of the methods PRTG Network Monitor (https://www.paessler.com/prtg) offers for monitoring bandwidth, to help you decide which methods you´d like to investigate in more detail.  The methods are covered in more detail in o…
Suggested Courses

649 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question