I haven’t posted in quite some time, as I’ve been studying quite a bit in either anything Network related or anything related to my current enrollment in college. Working on my BSIT – Information Security and Assurance. I may be keeping things short and to the point as of late, with the newest addition of my family set to arrive in August, 2011. Another boy!, making that 3 strikes on the little girl. I guess I’m out, but not according to my wife.
Anyway, I wanted to talk a little bit about an interesting problem I was presented with from a friend of mine. He was setting up a 2 link ether-channel on a Cisco 4500 series and ran into an interesting issue. You can see in the image below that the link actually negotiated what looks like a sub-interface on the ether-channel.
This was a little odd, as I’d never seen an ether-channel negotiation produce a sub-interface. So I did a little bit of digging and found some interesting information on what could have possibly happened.
It seems that the alpha-numeric number/letter combination assigned to the Po19A does indeed indicate a mis-negotiation of the link on the end of the 4500. I would imagine that this could be anything from a Speed / Duplex mismatch to STP finding it as a “redundant” link and causing it to re-negotiate the link on the fly. This, of course, would all be done using LACP, as this is the protocol that is used for negotiating a Link Aggregation that isn’t statically configured. I wasn’t able to produce this on my lab equipment, though I am still trying occasionally. If anyone reads this and has any possible insight as to what could have caused this, it would be greatly appreciated. For now, I will stick to my own hypothesis.
On a different note, I was able to take and pass my CCNA exam on May 11, 2011. I passed with a score that makes me happy and with a considerable amount of time left, so I definitely feel accomplished on that end. I also picked up the CCNP Certification Library for around 100 dollars off of Amazon.com – much to my wife’s dismay. I get the feeling she thinks I bury my head in too many books and spend too many hours in my dungeon while teaching myself all of this information. But she has been incredibly supportive, so I cannot complain.
I plan to keep updating this as I progress through my CCNA Security and CCNP and all the way to CCIE, studies. I will also update it with little tid-bits of things I learn or stump me in the field to see if I can get anyone’s opinions on these matters.
Until Next Time,