What you have is typical of many campus/business networks. The edge/access switches are typically in wiring closets where they connect up to patch panels. The network drops from the patch panels are pulled to locations in a particular room. The access switches are then uplinked to an aggregation or core switch. The bottleneck in this design is the uplink connection(s). Some switches come with or have the ability to add faster uplink ports which helps in eliminating or reducing the bottleneck over this uplink connection between switches. In older 10/100 switches, the uplink ports are typically 1 GigE. With 10GigE switches, the uplink ports are now 40 GigE. And at the top of the spectrum, there are 10/40 GigE switches which have the ability to do 100GigE.
Even though a switch has a faster uplink capability, running all the potential network traffic from the user/non uplink ports will still present a bottleneck which is commonly referred to as oversubscription. A technique to help overcome some of the oversubscription is to group multiple high speed uplink ports into a single virtual uplink called a LAG. The protocol used to do this is IEEE802.3ad or link aggregation. This protocol is only found in managed switches. Dumb switches don't have this feature. All switches support up to 8 physical ports in a LAG. Some support up to 16. LAGs are not a 100% holy grail for interswitch traffic as the LAGs operate under various configurable parameters to generate hashes to dictate which physical link in a LAG an Ethernet frame is sent. Sometimes depending on the hash algorithm used and the type of traffic will cause more traffic to be sent over certain ports which leaves the other ports under utilized.
Even though a switch has a faster uplink capability, running all the potential network traffic from the user/non uplink ports will still present a bottleneck which is commonly referred to as oversubscription. A technique to help overcome some of the oversubscription is to group multiple high speed uplink ports into a single virtual uplink called a LAG. The protocol used to do this is IEEE802.3ad or link aggregation. This protocol is only found in managed switches. Dumb switches don't have this feature. All switches support up to 8 physical ports in a LAG. Some support up to 16. LAGs are not a 100% holy grail for interswitch traffic as the LAGs operate under various configurable parameters to generate hashes to dictate which physical link in a LAG an Ethernet frame is sent. Sometimes depending on the hash algorithm used and the type of traffic will cause more traffic to be sent over certain ports which leaves the other ports under utilized.