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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.
What else can I help you with?
How do l1 l2 and l3 works?
How do L1, L2, and L3 work
What is a Transitive Property of Parallel Lines?
If L1 is parallel to L2 and L2 is parallel to L3 then L1 is parallel to L3.
If you have 3 light bulbs explain how you can determine they are connected in parallel circuits by unscrewing one bulb?
Unscrewing any light bulb in series will result in the others turning off. If they are in parallel, unscrewing one will have no effect. For example, say we have lights bulbs L1, L2, and L3, where L1 and L2 are in parallel and L3 is in series with L1 and L2. If L1 is unscrewed: L2 and L3 will stay lit. If L2 is unscrewed: L1 and L3 will stay lit. If L3 is unscrewed: L1 and L2 will turn off.
Is gomphosis a joint between L2 and L3?
Gomphosis is a type of joint that connects teeth to the jawbone, not between vertebrae like L2 and L3. The joint between L2 and L3 is called an intervertebral joint or a symphysis joint, where the fibrocartilaginous disc sits between the two vertebrae.
What cache does a itanium utilize?
L1, L2, and L3
What is a perpendicular with paralles lines?
If there are given two parallel line L1 and L2, and a third line L3 that is perpendicular to L1, then the line L3 must also be perpendicular to L2.
Do current processors have L1 and L2 caches?
l1 is in motherboards l2 is on processor newer processor has l3 too
Where is l2-3 located in the back?
The L2-L3 vertebrae are located in the lower back, specifically in the lumbar region. They are the second and third vertebrae from the top of the lumbar spine, just below the L1-L2 vertebrae and above the L3-L4 vertebrae.
On a 220 volt electric motor which is the neutral wire L1 L2 or L3?
If the motor wire numbers are L1, L2 and L3, it is not a single phase motor. It is a three phase motor. Also for future reference, a 220 volt single phase motor does not use a neutral.
How do you know which leads are L1 L2 L3 on a 3 phase 2 speed motor?
You can identify the leads by using a multimeter to measure the resistance between each lead. The resistance between L1 and L2 should be higher than between L1 and L3 and L2 and L3. You can also consult the motor's wiring diagram for guidance.
What type of cache does the Itanium utilizes?
It uses L1 L2 and L3.
What is L3 switch?
An L3 switch is sort of like a high powered router. These switches use hardware to route packets of information, as opposed to a regular router which uses software.
