Category Archives: Study notes

Why Hulc LED process consumes so much CPU on 2960 platforms?

In this post I’ll try to make an educated guess about what happens with Hulc LED process and why it appears to consume 20-30% CPU on Cisco 2960(S/X/XR/RX) switches. (N.B.: the issue appears to be present on Cisco 3750 / 3560 platforms as well) Symptoms If you monitor your switch via SNMP, you may quickly notice constantly elevated… Read More »

Cisco UCS HyperFlex FE class notes

Recently I attended a two-day class on Cisco HyperFlex by Tomaz Klancnik from NIL. It was quite interesting and packed with information about this new Cisco’s system. Here are the notes I took during the lectures and the labs. General Notes about Cisco HyperFlex Not developed internally; Not a complete acquisition / spin-in; software developed by Springpath… Read More »

VRF Lite basics

Sometimes while you do routing, you want to do it in a destination-based way and also differentiate routing for different sub-autonomous systems in your AS. Well, such behavior can be enforced by PBR, but it is not that scalable and it lacks some of the nicer things dynamic routing protocols bring to the table. Enter Virtual Routing and… Read More »