2. The encapsulated into a frame: the PPP agreement must provide special character as a , so that the receiver from the received bit stream can accurately identify the beginning and end of the frame position,
3. Transparency: the PPP protocol must ensure the transparence of data transmission,
4. A variety of network layer protocol: the PPP protocol must be able to in the support both on the same physical link in a variety of the operation of the network layer protocol , when a point-to-point link is connected is a LAN or a router, the PPP protocol must support both in the local area network (LAN) link is connected or router running on a variety of network layer protocol,
5. Many types of links: the PPP also will be able to run on multiple types of link,
6. Error detection: the PPP protocol must be able to received on the receiving end frame, and have the wrong frame immediately discarded,
7. Testing the connection status: the PPP protocol must have a mechanism to automatically detect whether the link is in normal work condition,
8. Maximum transfer unit: the PPP protocol must be for each type of point-to-point link set the maximum transmission unit standard default MTU,
9. The network layer address consultation: the PPP protocol must provide a mechanism to make the communication network of two layers of the entity to know or to configure the network layer address each other through negotiation,
10. Data compression consultation: the PPP protocol must provide a way to negotiate to use data compression algorithm,
11. When the PPP using asynchronous transmission, it escape characters as 0 x7d (01111101), and use the bytes, RFC1662 rules on the filling method is as follows:
(1) the information field in each byte 0 x7e into 2 byte sequences (0 x7d, 0 x7e),
(2) if a byte 0 x7d in information field, have 0 x7d into two sequence of bytes (0 x7d, 0 x5d),
(3) if the ASCII control characters appear in the information field, is before the character to join a 0 x7d bytes, alter the encoding of the characters at the same time,
Main features are: 12. LAN network owned by a unit, and the geographical range and number of sites are limited,
13. Some local area network (LAN) has the following main advantages:
(1) with functions of the radio, from a site can easily access the entire network, LAN host can be Shared on the LAN connection of a variety of hardware and software resources,
(2) facilitate the system expansion and gradually evolved, the location of the equipment can be flexible adjustment and change,
(3) improve the reliability of the system (reliability), availability (the availability) and survivability (survivability),
CodePudding user response:
Good good, to continue, come on