Application layer: through human-computer interaction to achieve a variety of service
Presentation layer: encoding, decoding, encryption, decryption,
The session layer: found that establish maintain and terminate the session
Transport layer: 1, through the port number to distinguish between different service scope: 0-65535, the static port (port) famous 1-1023, dynamic port number 1024-65535
2, provide reliable transmission confirm retransmission sorting flow control
TCP: transmission control protocol (TCP), a connection-oriented, reliable transport protocol (shaking hands three times, four times a disconnect)
UDP: user data protocol message, not a connection-oriented unreliable transport protocol
3, data segmentation: maximum length MSS 1480 b, the maximum transmission unit MTU 1500 b, data encapsulation and decapsulation
Network layer: logic through IP addressing router
Data link layer: LLC logical link control sub-layer as a FCS upper service check
MAC sub-layer medium access control through the MAC addresses to physical address
Definition: the physical electrical voltage, interface specification, optical properties
Second, data encapsulation and decapsulation
PDU protocol data unit
Data message
Four layer data segment
Three layers of packet
Data frames on the second floor
A layer of bitstream
TCP transmission control protocol (TCP) connection-oriented, reliable transport protocol
UDP user data packet protocol non connection-oriented unreliable transport protocol
Connection-oriented: three-way handshake four disconnect
Four disconnect
TCP header:
The UDP header:
IP header:
TCP/IP protocol stack:
Modeling the similarities: both are hierarchical, provide service support for the upper and lower each layer protocols are independent of each other each other
Difference: the OSI model have the agreement first, TCP/IP protocol is model, TCP/IP protocol stack is only applicable to the TCP/IP network, layer number of different
Three, the IP address
Ipv4 address: network and host bits, the IP address of the complete need to mask, dotted decimal 192.168.1.1 255.255.255.0
ABCDE five categories, by default, be resolved through the first eight categories:
A 0000000-0 0 0-1111111 to 127
B 10 000000-10, 111111, 128-191
C 110 00000-110, 11111, 192-223
D 1110 0000-1110, 1111, 224-239
E, 1111, 0000-1111, 1110, 240-254
Unicast address: ABC multicast address: D research using: E
The main class network: A 255.0.0.0/8 b: 255.255.0.0/16 C: 255.255.255.0/24
192.168.1.0 255.255.255.0 192.168.1.255
After A top 8 bits for network mainly 24 slots 2 ^ 2
24 -B after 16 for network mainly 16 before flight reservation 2 ^ 16-2
Before C after 24 for network mainly eight slots 2 ^ 8-2
There are private address in unicast address and classification of public address:
We have to pay for public address: global uniqueness use
Private address: local uniqueness without pay
Special IP address:
0.0.0.0/0 invalid address/default
Limited 255.255.255.255 broadcast address
127.0.0.1/8 local loopback address
192.168.1.00000000/24 on behalf of all the host within this period of 192.168.1.0/24
192.168.1.11111111/24 on behalf of this segment of the broadcast address
169.254.0.0/16 local private address
Four, subnetting
Along a/22 six subnet address range and usable
25 172.16.00000000.00000000/along/25 0.1-0.126
00.1 172.16.0.128/25, 0.129 -- 0.254
01.0 172.16.1.0/25 1.1-1.126
01.1 172.16.1.128/25 1.129-1.254
10.0 172.16.2.0/25 2.1-2.126
10.1 172.16.2.128/25 2.129-2.254
Subnetting to a large network is divided into some small
VLSM variable-length subnet mask
Subnet
Summary will be a few small network converge into one large network
CIDR classful inter-domain routing
Super net
Mother number of wire is consistent, in the same place, to remove different bit
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24
4.0/24
192.168.000000
01.0
Route summarization:
Routing aggregation 172.16.1.32/27 172.16.1.00100000
172.16.1.64/27 172.16.1.01000000
172.16.1.96/27 172.16.1.01100000
Summary: after 172.16.1.0/25
The role of the switches
1. The infinite extension of transmission distance
2. Implement unicast
3. Solve collision domain
CodePudding user response:
What thing content is like a few plain