Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

Redundant Routers failing at the same time.

Hi All,

First post here but maybe someone can help.

We are having trouble at one of our datacenters with two redundant 3750s. Both ports for external traffic are dieing at the same time. Internal traffic continues to flow. The configuration is pretty basic with the ports carved up into vlans. Other than that is factory issue except for custom passwords.

We are trying to trouble shoot what is happening. We have the exact same setup in another location and it has not been down since we installed the switches about a year ago.

What we think it may be is :

1. Old version of operating software on the switch that is buggy.

2. Something upstream from us that is poisoning the external ports causing them to crash.

3. An attack on the ports externally that is causing them to crash.

Anybody have any insight that can get us headed in the right direction?

Many thanks

Cisco Employee

Redundant Routers failing at the same time.

Hi Sean,

pretty weird issue you have.

I would tend to exclude an IOS bug which shows up at the same time on 2 different switches... (but never say never).

I would first investigate about what happens at the time of the issue and before that I would like you to elaborate what you mean by 'ports dieing'. Do they go up/down? they get error-disabled? Do you see any message in the log?

Can you attach a show interface x/x (external link) and then one after the issue pops up from the 2 routers?

When you say at the same time, do you mean at the same time of the day every day (i.e. every day at 12.45pm) or simply it happens simultaneously on the 2 routers?

If it happens every day at the same time, what else occurs at that time (backups - traffic peak - SP doing something on the links etc.).

What is connected to those 2 3750s? The same SP or 2 different ones? If there are 2, are the circuits terminated to the same physical box?

As you see there are a lot of questions that might put us on the right track.



CreatePlease to create content