Cisco 3750 Issue

Posted on 2012-08-20
Medium Priority
Last Modified: 2012-09-11
I have a stack of 6 3750's in my MDF. Additionally, I have 1 additional 3750 in an IDF on another floor, connected via fiber/SFP to a gig port on each end. When I initially connected the fiber in the IDF, it reset the entire 3750 stack, which bounced 150 phones on my main floor. Last week, the power went out on the other floor and when it came up, it bounced the whole main stack again. I didn't put it together until it happened again.

Anyone have any ideas why it would do this when I connect the IDF switch?
Question by:centricC
1 Comment

Accepted Solution

bplantier earned 2000 total points
ID: 38315704
I suspect spanning tree to be the source of this problem.
When you plug your new 3750,  your spanning tree needs to converge again.

If you dont have loops in your layer 2 topology, maybe what you can try is to enable portfast in the trunk port between your 2 switches.

On stack switch:

int Gig X/Y
 spann portfast trunk

Open in new window

plus, you must be sure that the new switch will not be the root bridge of the spanning tree domain.

On stack switch:
spanning-tree vlan 1-1000 priority 0


Open in new window


Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

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

This article explains the fundamentals of industrial networking which ultimately is the backbone network which is providing communications for process devices like robots and other not so interesting stuff.
In this article, the configuration steps in Zabbix to monitor devices via SNMP will be discussed with some real examples on Cisco Router/Switch, Catalyst Switch, NAS Synology device.
Internet Business Fax to Email Made Easy - With  eFax Corporate (http://www.enterprise.efax.com), you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, f…
Michael from AdRem Software outlines event notifications and Automatic Corrective Actions in network monitoring. Automatic Corrective Actions are scripts, which can automatically run upon discovery of a certain undesirable condition in your network.…

621 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