I know this topic has been discussed many times with supported documents like
But I am sitting with an issue where I need to try and understand why this is happening.
I have two sites Active / standby
At each site one of the switches connecting 4 routers each per site. The configuration between the switches / routers are all forced to 100/full
Now with this setup I can ping between the routers 100% without packet loss.
However between 2 routers let’s call them router A and router B when they ping one another I we see packet loss. Just when these 2 are communicating with one another we see packet loss
Any other device can ping both of them 100%. The cables have been replaced both ends.
Finally we got a way of letting them talk fine, having the router A forced 100 / full and the switch at auto.
Now having the setup duplicated, I find it strange that the same kit / make / model / IOS works with 100 full and on the other side we had to put on the switch auto.
Is there any explanation, or something else we can look at to try and explain this one?