Core, distribution, and access switches are mostly conceptual. One switch might be an access switch for one company and a core switch for another. The manufacturers will MARKET different switches different ways based on their overall ability to either tightly/cheaply bundle user ports, or their ability to move massive amounts of traffic quickly.

Switching can be a VERY deep rabbit hole, let us know how deep you want to go.

so, a switch can be a core switch or distribution switch simultaneously. if i want to make a core switch to centralize servers or other distribution switches, some settings is required to make the switch become a core switch, isn't it?

Core switch is a concept, like the OSI model. There are certain settings that will normally be associated with core switches.

If you could spend a little time on Cisco's website pages like this might be helpful http://www.cisco.com/en/US/netsol/ns...s_package.html but some time with a CCDA study guide might be more directly helpful.

thank you very much for your help! it will be very helpful for my network design.

thanks a zillion...that really helped...!