Marco Linux Learning Note II--Network

1.MAC Media access Control

is a solution to resolve the underlying data traffic conflict. Thus, for each host that accesses such a network an ID identifier, this ID identifier is called the MAC address.

2.CSMA/CD (Carrier sense Multipath access collision Detection, Carrier listener Multi-access conflict detection), Linetype network

Ethernet Ethernet The core of the logo.

3.token-ring (IBM) technology

A scheme for resolving conflicts in a ring network. But IBM's patent restrictions failed to spread.

4. Star-Shaped network

The hub is used to connect a host of hosts, thus forming a star-shaped network.

This is a variant of the bus structure. or a line, but not a line, but a device, but actually the hub inside is a line, and the hub has made a lot of interfaces, so that you can easily add a host. It is logically still a total linetype network.

5. Network Bridge

Can be roughly understood as a repeater, used to amplify the signal or something.

A network bridge is a device that connects two networks. when a local area network is too many devices conflict will be particularly prone to the use of Mac to deal with, the efficiency of communications will be greatly reduced, so the bridge is generated! It's like a family has a lot of people, need to split up, but they still have to communicate. So a large local area network is divided into several small networks, these small network between the use of bridge connection. Note the difference from the Internet.

There is a table inside the bridge that can be used to determine if the packets sent to this small network, if it is sent to this small network, then do not need bridge forwarding.

6. Switch

When a network bridge switches a large network into two small nets, the likelihood of collisions is reduced by half.

One limit is the case: one of the exits of the bridge has only one host. -----> This device is the switch!!

The core of the switch is the one inside the table!

The switch isolates not broadcasts, it isolates conflicts. Inside a small network can also be called the conflict domain.

7. Hardware devices for the connection layer

Hub Hub--Network bridge---switch switch

Reason for the existence of the 8.IP address

The switch isolates not broadcasts, it isolates conflicts. So, with no more switches to solve the broadcast storm (too many broadcasts) problem, so that a switch is located in the total address of a small network, we call it a logical address (he is the analog, he is used to identify the Exchange network), and it is called an IP address.

The MAC address works just for broadcasting! So use a logical address (IP address) for better forwarding. (Note: This seems to be a question of finding the right granularity )

IP has only one simple function: He is used to forward messages between networks. He is also just used to identify whether it is a local network or a remote network .

The change of IP address and MAC address during packet forwarding

The IP address remains the same, and the MAC address always changes (because the MAC address is not cross-network )

9.ARP(Address Resolution Protocol)

Address Resolution Protocol. Resolves the IP address to a MAC address.

The MAC address is an envelope, and IP can be seen as the beginning of the letter. The process of sending (forwarding) is constantly changing envelopes, but the beginning of the letter cannot be changed.

The necessity of 10.MAC existence

The IP address is used to find out what is in a network, and ultimately to be broadcast by a Mac. Mac is used to mark local communications, and he is constantly passing on, constantly changing, because its Mac is only in the local network to realize its own value, not in this small network it will change.

11. Routing Automatic Learning Generation routing table

RIP Protocol, RIP2

12. Default gateway ?????

Can be understood as the interface between the switch and the router.

13. Port number

The available ports for each host are: 0-65535

For the client, use a random interface that is not being used on the line. And the server side will not, a port behind a process is listening.

Http://www.cnblogs.com/chenbuer/p/3842281.html

14.IP Address

Host bit all 0: network address

Host bit full 1: Broadcast address

ICANN is buying an IP address with it.

15. Routing Table

A route entry, when the destination address is a host we become a host Route , the destination address is a network when the network is routed . The selection is the best match when routing.

Routing aggregation is the merging of many small subnets into a single large network, which can improve router performance by reducing the time it takes to find the route entry to find.

16. Configuration Files

The system reads the configuration file when it is started.

the IP belongs to the kernel and does not belong to the network card .

Network card in 18.Linux:

Lo: Local loopback

Ethernet Card: EthX

PPPX Point-to-point