Common operational misconceptions

Ray Soucy rps at
Thu Feb 16 13:17:03 UTC 2012

I help with networking curriculum and labs here at the University of
Maine, especially for network security.

There seems to be (even among faculty) a gross misunderstanding of
Layer-2.  Nearly every textbook starts with IP, and talks about it as
if we were 20 years in the past.

I've found starting off with some history on Ethernet (Maine loves Bob
Metcalfe) becomes a very solid base for understanding; how "Ethernet"
today is very different; starting with hubs, bridges, collisions, and
those problems, then introducing modern switching, VLANs, broadcast
domain's etc.

Then expanding on that by introducing Layer-3 starting with its
relationship to L-2 (ARP, how packets are manipulated when a host
makes the determination if a packet is on link or needs to be routed,

On Thu, Feb 16, 2012 at 8:03 AM, Owen DeLong <owen at> wrote:
> On Feb 16, 2012, at 4:31 AM, Jared Mauch wrote:
>> On Feb 15, 2012, at 7:55 PM, Nathan Eisenberg wrote:
>>>> IPv6 is operational.
>>> How is this a misconception?  It works fine for me...
>> I think he left off "In Japan".  There's been a lot of local politics as it relates to the broken nature of IPv6 in japan.  When its there, it's not globally accessible in many cases (at the consumer or last-mile level).  Most (all?) major backbones are IPv6 capable these days, but in some cases it's 6PE vs "native".
>> IPv6 is operational and does work, but like any protocol there are issues.  If you are unaware, take a look at what people are trying to put into IPv4 still at IETF.  The fact that the IPv6 day went so well last year, and the IPv6 launch is coming quickly is a reminder its real.  Me?  I can't wait to have this behind us.  (Oh, and if you're not at least routing your IPv6 space to your lab/NOC LAN, get on it.  Even if you have to poke the 'security' guys who think you need an IPv6 NAT in the eye).
>> - Jared
> Yes, I'm well aware of the problems being created by the attempts by NTT to force the government to let them be a residential ISP.
> Owen

Ray Soucy

Epic Communications Specialist

Phone: +1 (207) 561-3526

Networkmaine, a Unit of the University of Maine System

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