Monday, February 10, 2020

What 'stupid' errors still trip you up after years in the networking business?

I have been doing networking in various roles since early 2000-something. Got certifications, been working on a quite a few tier-1 networking brands.

And yet, I regularly get tripped by 'stupid' or trivial issues. Most often because I inherit someone else's mess or someone else did the hardware before I got involved. But once in a while it is my own mess.

Some of my personal favorites:

  • misconfigured spanning-tree

"Both devices have link on the right interface, in the same vlan, right IPaddress. Cannot ping. ARP ok. LLDP works, now it doesn't, now it works again. Hey, I got a ping response. Now it is dead again." Yeah, the box is very busy processing packets.

  • wrong BGP AS or wrong BGP auth key

"I have checked EVERYTHING. Why can't I establish this peering?" No, I didn't check everything...

  • cat5 cables, missing locking tab on RJ45 connector

"I had link when I left. Or: It used to work with the other, older box." I rarely touch hardware anymore. When I do, dodgy, old cables have a very short lifetime.

  • DNS not resolving to what I think it does

"Oh, you're talking to *that* nameserver. Or: oh yeah, there's an entry in /etc/hosts...." But this is probably only me.... /s .

  • wrong SNMPv3 auth or privacy *protocol*

"I *know* I set the right auth/privacy password. I just redid it for good measure. Still doesn't work." Most often when configuring a new type of device, and my NMS of choice does not have the exact combo of auth/privacy password/protocol configured.

I guess the common denominator is that these do not happen too regularly for me to suspect them from start. What is your personal 'trivial' tripwire?



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