Denis Borchev

I am a networking engineer, a geek and a generally nice person=) Computer Networking Engineer with some experience; MSc Applied CS, CCIE #53271

Author Archives: Denis Borchev

How to safely transform a routing domain

As part of my job as a Senior Network Engineer, I develop procedures for undertakings of varying complexity. In this post I’m describing a technique that greatly simplifies any project where a routing domain is expected to churn (i.e. neighborships going up and down, routes flapping), when such event is undesirable. Motivation I developed this technique for a… Read More »

Paper: Scanning the Internet for Liveness

An interesting paper where the authors are building a better way to scan the Internet. Shehar Bano et al. Scanning the Internet for Liveness // ACM SIGCOMM Computer Communication Review, Volume 48 Issue 2, April 2018 Liveness—whether or not a target IP address responds to a probe packet—is a nuanced concept without a simple yes/no answer. Responsiveness… Read More »

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 »