Author Archives: fitzi

About fitzi

I'm a network operator by day and by night I spend my time working through service provider certification tracks as well as teaching myself python. I am looking to get more involved in the automation of repetitive tasks.

Quotes: Non uniformity

I saw this tweet a while back which pretty well sums up most IT operations in the industry in general and why it needs to change.


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I saw a tweet from Jeremy stretch (@packetlife) the other day about showing the ping statistics in linux without stopping the ping command which I had never seen used before (I obviously should have RTFM :P).  After which @jmhuwe and @synteki chimed in with the windows and OSX equivalents as per the below, thanks!

Linux – CTRL + \

Windows – CTRL + Break

OSX – Control + t


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multiple spanning tree

Working on renewing my knowledge of multiple spanning tree, in the lab I have three switches in a triangle topology.  I have configured mst instance 23 and in this instance vlans 100-400 on Switch2 and Switch3, here I have also configured Switch2 as the mst root bridge for instance 0 and 23.

When I issued the show spanning-tree mst command, in the output I can see this odd reference to PVST:

From the above screenshot g0/0 is connected to Switch3 which is also running mst and g0/3 is connected to Switch1 which is not running mst.

After some searching on the internet I found the blog linked below which points out that the above output is simply indicating that g0/3 is a mst boundary port meaning that the switch which is connected to this port (Switch1) is not running mst.

Since this is the case Switch2 will generate and send a PVST bpdu on g0/3.  Note that I have configured mst root primary on Switch2 for both instance 0 and 23.

I also found an article on which explains in detail how mst switches inter operate with non mst switches:

PVST Simulation on MST Switches

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