Basically a layer 2 switch operates utilizing Mac addresses in it's caching table to quickly pass information from port to port. A layer 3 switch utilizes IP addresses to do the same.
While the previous explanation is the "What", for folks in networking the following "How" is far more interesting.
Essentially, A layer 2 switch is essentially a multiport transparent bridge. A layer 2 switch will learn about MAC addresses connected to each port and passes frames marked for those ports. It also knows that if a frame is sent out a port but is looking for the MAC address of the port it is connected to and drop that frame. Whereas a single CPU Bridge runs in serial, todays hardware based switches run in parallel, translating to extremly fast switching.
Layer 3 switching is a hybrid, as one can imagine, of a router and a switch. There are different types of layer 3 switching, route caching andtopology-based. In route caching the switch required both a Route Processor (RP) and a Switch Engine (SE). The RP must listen to the first packet to determine the destination. At that point the Switch Engine makes a shortcut entry in the caching table for the rest of the packets to follow. Due to advancement in processing power and drastic reductions in the cost of memory, today's higher end layer 3 switches implement a topology-based switching which builds a lookup table and and poputlates it with the entire network's topology. The database is held in hardware and is referenced there to maintain high throughput. It utilizes the longest address match as the layer 3 destination.
Now when and why would one use a l2 vs l3 vs a router? Simply put, a router will generally sit at the gateway between a private and a public network. A router can perform NAT whereas an l3 switch cannot (imagine a switch that had the topology entries for the ENTIRE internet!!). In a small very flat network (meaning only one private network range for the whole site) a L2 switch to connect all the servers and clients to the internet is probably going to suffice. Larger networks, or those with the need to contain broadcast traffic or those utilizing VOIP, a multi network approach utilizing VLANs is appropriate, and when one is utilizing VLANs, L3 switches are a natural fit. While a router on a stick scenario can work, it can quickly overtax a router if there is any significant intervlan traffic since the router must make complicated routing decisions for every packet that it recieves.
The difference between Layer 2 and Layer 3 switching is the type of information inside the frame that is used to determine the correct output interface. With Layer 2 switching, frames are switched based on MAC address information. With Layer 3 switching, frames are switched based on network-layer information.
A layer 3 switch has routing capability like a router. However, it also has layer 2 switching capabilities like a switch. To fulfill both functions, layer 3 switches will generally have a greater number of ports than most routers.
The answer choices are not provided for this question. Also this question was miscategorized it should be a networking question not science.
A Switch is a Layer 2 device as they operate in the data link layer
It is a layer 3 switch
I believe it's a router. I have this question on a test the choices are. router, hub, layer 2 switch or firewall. I answered layer 2 switch. It was wrong.
I believe there is no such thing as switching "from layer 3 to layer 2". Switching is either done within layer 3, or within layer 2.
because one layer is the electrical part, and the other layer is the place where the switch is on.
Layer 2 switches are working based up on the MAC address and layer 3 switches are working based up on the ip address
A layer 2 switch uses the MAC address to determine which port to switch the frame out of.
A switch is mainly a layer 2 device (because it switches on the MAC address)
Routers operate at layer 3 of the OSI model while switches operate at layer 2. The data transmission form of a router is called a packet while in a switch, it is called a frame. Routers are mainly used in wide area networks while switches are used in local area networks.