Current Focus, an update

So much happening since my last blog entry.  I’m currently working on two topics at the moment,

  • IPv6 transition architecture
  • SDN/NFV architecture

These are interesting topics respectively.

With IPv6 it seems the more one progresses with this protocol the clearer it becomes that the challenges which exist are not with IPv6 natively 1 so much as the concern with enabling IPv6 and IPv4 to co-exist, with an emphasis on intercommunications between them.  Seems a bit silly I guess, but from what I’ve observed and seen so far, this is the challenge (IPv4 <-> IPv6).  It’s not impossible, however it does require careful consideration; there are many approaches that attempt to solve for the co-existance between IP protocols, each with their own strengths and weaknesses.  So the good news is there are solutions ….and with these solutions the concern becomes choosing wisely.  Everyone will have a uniq perspective on this given their line of business and network needs.  One size does not fit all.

With SDN/NFV this is like a snow-ball rolling down a mountain, it’s gaining momentum and gaining in size.  Managed service providers and hosting providers have capitalized on how to operate with SDN/NFV.  Network service providers are looking to capitalize, with some Tier 1 services providers already implementing SDN/NFV.  I see programming as a corner stone and I see networking know-how has a corner stone.  Evolving with the industry is a requirement for success.

So, having written the above, I’m off now to delve into cloud image creation.

~ Jeff


  1. I will say the immediate exception I see here is the residential gateway (RG) devices.  Manufactures in the market space appear willing to implement IPv6 solutions into their products; however they want a to know how may new orders can be placed.  If it is not immediately obvious what the problem is with this statement (new orders) then please consider there are millions of RG devices already deployed.  Does the existing deployed hardware of these RG devices support IPv6?  If do support IPv6, which transition protocols are supported? 

Linux /boot Partition Full

This morning I spent time updating the various VM images I use with bug and security fixes.  My CentOS 7 VM presented a notice to me that it’s /boot partition was nearly out of disk space.

Normally a quick reference and delete of the older files would address the immediate need to free-up disk space; however this would not address the long term management of running out of disk space (again) as updates are applied.   There is also the question of breaking package management continuity by removing files by hand.

Quick Internet search took me to a blog entry which addressed this very topic.  https://rmohan.com/?p=5475

By default CentOS 7 will keep up to 5 different versions of an installed package laying around.  Interestingly, the yum.conf man page says that the default value is 3 different package versions.  Yet the value I found in the CentOS 7 yum.conf file was 5.  Go figure.

So two things…

  1. I set the Yum configuration to keep only 2 copies.
    shell# vi /etc/yum.conf
    installonly_limit=2
    (save and exit)
  2. I purged the older kernel files in the /boot directory using package-cleanup tool.
    shell# package-cleanup --oldkernels --count=2

This took care of me.  Please visit https://rmohan.com to see output from the before, during and after using package-cleanup.