This lesson we have to learn about the PPP and HDLC protocol.
Both protocols that do are typically used for wide area network which, we first look at the concept of the WAN. It is usually connected across a large range of physics, it covered a range from tens of kilometers to thousands of kilometers, can be connected to multiple cities in many countries, but also across several continents, several ocean, providing a far communication distance, form an international network remotely. We now use the Internet as the Internet, it is an example of a WAN.
WAN subnet that communication it mainly uses a packet-switched technology. That this packet switching technology, we will be after the network layer specific chapters unfold, we can clear it up. Subnetworks that may utilize the wide area network is a public packet-switched network, a satellite communication network and the wireless packet-switched network. It will be different regions of a computer system or a LAN connected, a purpose of resource sharing. So our wide area network, it is possible to set up a multiple LANs together such a large network. Well, this is an illustration of the wide area network, which is the middle of a large wide area network, local area network connects two next to it, so I realize the interconnection between the widely separated LANs.
That can be seen in the wide area network which, among us there are many such nodes is called node switch. The switch node that it is actually a device link layer, it is a switch. But then it functions much like a router, it is used to forward packets. But the difference to note is that this node can only switch it to forward packets in a single carrier's network. And this router does, that is, after the network layer devices to learn, that can forward packets between multiple networks. That some students might be asked, what is the only WAN node switch it? of course not. WAN them, we can have switches may have hubs, routers can have more network layer. So, a big difference between WAN and LAN, WAN that it covers the network architecture level, from the physical layer, link layer up to the network layer. But then the LAN, it only covers the physical layer and link layer two levels. The LAN which it is widely used multiple access technique, is such a logical bus on the total multi-access technique. And a wide area network which is what we usually use point, a receiving end a transmitting end, a full-duplex connection to each other by a half duplex communication link or a connected mode. Of course, what they both networks, the emphasis is not the same. Which emphasized the wide area network is a shared resource, and in which the LAN data transmission more emphasis on it. Although its WAN LAN transmission rate than the transmission rate is higher, because it is to achieve long distances through communication, so the speed can not neglect. But it is very far away and because of this, resulting in wide area network among its local area network than the propagation delay propagation delay longer. Therefore, the WAN is not how this emphasis on data transmission. Because it again soon, or to have such an influence of the delay spread. And this does LAN, it is necessary to emphasize data transmission. WAN only emphasized the sharing of resources on it. That this lesson we talk about it, and the PPP HDLC protocol is the most commonly used among the two WAN link layer protocol.
First we look at the PPP protocol. It is the PPP Point to Point, Point to Point Protocol is the most widely used as a link layer protocol currently in use. For example, our dial-up Internet users in the use of broadband networks, PPP protocol are generally used.
That the PPP does it only supports full duplex link. HDLC protocol is to learn after only supports full duplex link.
That Next we look at some of the requirements to be met PPP protocol. Ah The first requirement is that the PPP agreement must be simple. Because at that time when architecture design Internet, the most complex part of them are on the TCP protocol. And this IP protocol it is also a little more complicated. But it would be simpler than TCP, IP protocols that this layer does it mainly provides an unreliable packet services. Therefore it does not have the link layer
