Hello to everybody.I studing CCNP switching and i can't understand why 80/20 rule of local VLANs is more efficient than 20/80 rule of End-to End?
The 80/20 or 20/80 rules are not about efficiency. It is simply a characteristic of the nature of data flows within a VLAN. The concept of end-to-end VLANs was fine for communication that primarily involved the stations in the particular VLAN and only little fraction of the traffic went out to "non-members". However, today, think of data centers, server farms, cloud services, Internet access, etc. - regardless of which VLAN your PC is located, the majority of your data traffic will flow out your VLAN towards these locations. Hence, the characteristics of today's traffic is vastly different from what it once was. Therefore we are talking about 20/80 rule, and that is the reason why we do not usually strive to contain all similar stations in single VLAN, because it does not make much sense... they don't talk to each other that much, rather, they talk most of the time to someone who is outside their own VLAN.
In other words, the 80/20 or 20/80 rule is not a result of using end-to-end or local VLANs, it is quite reversed - because the traffic is of 80/20 or 20/80 nature, we choose between end-to-end or local VLANs.
Please feel welcome to ask further!