0:00seven-layer OSI model animation
0:06yeah
0:09application
0:10you later
0:11station layer
0:13session layer
0:15transport layer
0:17clear
0:19data link layer
0:21physical layer
0:30application layer this is where you find network applications such as male web
0:35file transfer management through SNMP remote connections such as with tell me
0:40that now when we talk about applications people immediately think of things like
0:44Microsoft Word or outlook for powerpoint and those are the applications that
0:50could connect here if they needed a network connection but generally when we
0:54talk about applications we're talking about network specific applications
0:57again file transfer web services that sort of thing that layer 7 the data
1:02grams are called upper layer data in fact that the top three layers are all
1:06kind of lumped together and the data grams are called upper layer data layer
1:126 is the presentation layer it provides a context for communication between the
1:16layers for example ascii characters are described here
1:20also you'll find encryption and decryption at layer 6 compression
1:24happens here and data grams here called upper layer data here's a way to think
1:28about the presentation layer
1:30maybe you remember it it prepares the data from the lower layers for
1:34presentation to the application layer
1:38next is the session layer and it controls dialogues between computers
1:43this is handshaking takes place here for example
1:46it also controls duplex in termination and restarts diagrams at the session
1:51layer still called upper layer data because again the top three layers of
1:55kind of lumped together
1:56now we get into the transport layer this is layer for it provides transparent
2:02transfer of data protocols that operate here are tcp and UDP tcp for reliable
2:08connections and UDP for unreliable or non reliable
2:13maybe it's a better way of describing it in this case not reliable is not
2:16necessarily bad it simply means there's less overhead because there isn't the
2:19error checking that happens with TCP nor the confirmation of delivery
2:24so use TCP when you need to ensure that the data grams arrive at the destination
2:29and use UDP when latency is more of an issue because there's more overhead
2:35associated with TCP good example of that is void packets often will use UDP
2:39because
2:40there are more sensitive to to latency than they are to packet loss
2:45the transport layer provides internet connections also reliability flow
2:50control and the data grams at layer for the transport layer are called segments
2:55next the network layer this is layer 3 this is where routers operate it
3:01provides connections between hosts on different networks this is where you
3:04find protocols such as ipv4 and ipv6 going to go over the different protocols
3:09with you in a moment but those are two in particular that would be associated
3:14with layer 3
3:15as we mentioned routers operate here so this is where writing of packets takes
3:18place the the thing to think about with the network layer is that first bullet
3:23it says provides connections between hosts on different networks
3:27if you're on the same network than those connections take place at layer 2 but on
3:30different networks its layer 3 and again the data grams at layer 3 are called
3:35packets layer 2 is the data link layer provides connections between hosts on
3:41the same network
3:42this is where you find ethernet operating mac addresses operate at layer
3:46layer 2 so IP addresses or ipv6 addresses are like three mac addresses
3:52sometimes called hardware dresses are at layer 2
3:56in fact mac is the acronym for the media access control which is a sub layer of
4:01layer 2 and the data grams at layer 2 are called frames
4:05finally the physical layer this is where we describe electrical and physical
4:10specifications for devices are devices that operate here
4:14cable and connectors hubs repeaters and the data grams
4:18actually we'll just say the data at layer layer one is simply called bits
4:22something to think about when you're troubleshooting you always started later
4:27one so when people say start troubleshooting the physical layer layer
4:301
4:31they're talking about the OSI reference model you want to check and make sure
4:34things are plugged in turned on your the right kind of cable-and- right kind of
4:37connectors
4:42Center
4:49transmission medium
5:01receiver
5:03let's see how the data are
5:05flowing through the seven layer
5:27haha
5:29finally conclusion of seven-layer OSI model
6:15yeah
6:20thank you for watching this video