Differences between vrouters, hubs, and vswitches

Differences between vrouters, hubs, and vswitches

Ling huchong entered Huashan when he was 14 years old. He was eight years old when he was lazy. During the day, Yue wuqun gave two people a guide to jianfa. At night, Ling huchong told a story to her sister to help her fall asleep. Later, Yue Bu group received Lao de Nuo, Lu Da and other apprentices, and was busy practicing Zixia, so there was no time to give advice to his disciples. As a result, he made a hub. From then on, Huashan school realized electronic education, and Yue weiqun gave lectures to every apprentice on the Internet. This method was quickly promoted within Wuyue jianpan. In order to interconnect Wuyue Jianpi, a router was developed by Zuo Leng Chan, the manager of Songshan school, to enable interconnection between Wuyue Jianpi. Ling huchong told stories to her sister through the Internet at night.

Soon, laashan was sixteen years old and turned into a slim little girl? Niang. Did Linghu Chong find himself? My eyes are always involuntarily stuck on my sister-in-law. When I was with my sister-in-law, I always heard a strong heartbeat. after a while of tea, I finally spent one night, ling huchong sent a romantic poem to Xiao Shimei online: You are wind, I am sand, You Are bees, I am flowers, you are combs, And I am hair, you are toothpaste and I am a toothbrush. The next day, at a regular meeting of the Huashan school, Ling huchong came to the meeting room with a bad impression and found that the younger sister was hiding behind master with a red face, while other younger siblings were secretly smiling at themselves, A naughty younger brother called his toothbrush brother and ran away. Asked Lu Dayou, he realized that he was using netxray to capture all his online masterpiece. Ling huchong was excited, so he studied RFC in closed doors and developed lanswitch. It can identify the MAC address of the device. In this way, only the data sent by Ling Hu Chong to xiaoshimei can be received by herself. At night, Ling huchong can tell stories to her sister online with peace of mind. Occasionally, her hand itch can also give her a few words that I want and can't say at ordinary times. Then, she glared at her face and imagined her facial expression. Lanswitch is a layer-2 switching device. It can understand the MAC address of the layer-2 network protocol address. The L2 Switch constantly collects data during operations to create its own address table, which is quite simple and mainly indicates the port on which a MAC address is found, when the switch receives a data packet, it checks the target MAC address of the packet and its address table to determine the port from which the packet is sent. Instead of the hub, any sender data will appear on all the ports of the hub (whether or not required for you ). In this way, lanswitch improves the efficiency and security of the system.

In the next year, yueda group recruited a large number of disciples, and the Huashan school was greatly expanded. The lanswitch was used for many secondary connections. However, it was inevitable that the disciples were mixed. At that time, the three and four generations of disciples of Huashan sent worship the man Tian bo
Guang established a tianxie, who often argued that the competition was eight hundred meters or 1 km meters.
There is a big law called Li Hongzhi, Which is broadcasted inside the Huashan school every day. What makes Ling yuchong unable to stand is that, with the master
As the age grows, it becomes more and more arrogant. Every sentence must be repeated for 20 times and then broadcast on the Internet. Ling huchong and Xiao
Shi Mei, Lu Dayou, and others use a broadcast domain. However, if another lanswitch is used, he certainly won't agree. So he modified the lanswitch software, lu Dayou and others divide themselves into a virtual network (VLAN). When others use another VLAN, the broadcast packet is sent only within the VLAN, And the VLAN is connected through the router. Yue binqun is also deeply affected by Tian Xie, Li Hong, but in order to fight against Zuo Leng Chan, Li Hong can only endure the work while employing people. I am very happy to know about this, but he is still responsible for making changes to the software without permission, let him go to the cliff for a year without going down the hill within one year. In the Huashan school, VLAN is re-used for subnet division, which is divided into five subnets: Master and master Niang, Master girl, and Lin Ping in a VLAN, And the Sending team uses a VLAN; tian Xie's disciples use a VLAN, while other disciples use a VLAN, and there is also a separate VLAN on the cliff. Ling Hu rushed to the cliff, not sad. Finally, the world is quiet. Relying on the router of Zuo Leng Chan, Ling Hu Chong can also tell stories and chat to her sister-in-law on the Internet every day.

The introduction of LAN switches enables dedicated bandwidth between network nodes. However, for L2 broadcast packets, L2 switches broadcast on each network node. At the same time, for MAC addresses that cannot be recognized by L2 switches, they must also be broadcast in the broadcast domain. When multiple L2 switches are connected, all devices in the L2 switching network receive a broadcast message. In a large Layer-2 broadcast domain, a large number of broadcasts greatly reduce the efficiency of layer-2 forwarding. In order to avoid broadcast storms caused by broadcast on large switches, A L2 Switch Network must be further divided into multiple virtual networks (VLANs ). In a virtual network (VLAN), the information sent by a workstation can only be sent to other sites with the same virtual network number (vlanid) members cannot receive the information or broadcast frames. Virtual networks (VLANs) can be used to control broadcast storms on networks and increase network security. Communication between different virtual networks (VLANs) must be performed through routers.

However, happiness will always be short-lived, and there will always be endless troubles. With the increasing power of the entire Wuyue Sword School, the speed of routers is getting slower and slower. Linghu Chong finds that every time she tells a story to her younger sister, her answers always come late and seldom talk. She always says "well", "oh" or "I listen ". At last one day, the router could no longer be pinged, and Ling Hu Chong did not receive a message from her sister-in-law for three days. She couldn't help looking for her sister-in-law on an empty display screen. On a sleep night, she secretly went down the hill, when I got to the front of my sister-in-law's window, I found my sister-in-law chatting with Tom Online. I didn't pay attention to myself. I felt sore and went back to the cliff, causing a serious illness. After being ill, I worked hard and finally made a router one day. At this time, Ling Hu Chong found that Huashan had thirty VLANs, And the router had to allocate an interface for each VLAN, the interface is not enough. In addition, the switching speed between two subnets through the router is much lower than that of layer-2 switching.

After a L2 Switch is divided into virtual subnets, a problem occurs: forwarding between different virtual subnets needs to be achieved through other routers. Forwarding between different VLAN nodes of a layer-2 switch needs to be achieved through a router device, which greatly wastes ports, the high cost and low efficiency of a router make it unable to meet the three-layer forwarding requirements in the case of a large number of subnets. In this case, the concept of three-layer switching is proposed.

This evening, Ling Hu was very lazy and relaxed. At this moment, a dark shadow appeared in front of him. It turned out to be an old man of the wind and fairy bone. After hearing the questions from Ling Hu Chong, Feng Qingyang said: the router interface is not enough. You can leave the router inside the lanswitch. The switching speed is slow because the router looks for a CIDR Block route, while lanswitch directly queries the Mac corresponding to the port, of course, the speed is fast. Why can't I find the port based on the IP address? As long as he heard it, he admired it, but he still did not understand that there were so many IP addresses and frequent changes. How can he directly find the port? Feng Qingyang said:

"Sit down first. Let me ask you, how many disciples are there in Huashan school? "

"About sixteen thousand. "

"Do you know where they live? "

"I don't know. "

"Yue Bu group asks you to find someone who doesn't know where to live. How can you find someone? "

"Check the phone number system of Huashan Pi, find his address, and then look for him. "

"How can I find this person again after you come back? "

"How to..., check the phone number Inquiry System of Huashan school, find his address, and then look for him. "

"Do you know the address of this person? "

"Yes, but master said that Huashan has so many addresses and they often change. You don't need to know the addresses. "

"Yue weiqun, this kid, has taught his disciples to become wood! I ask you, what do you think you should find? "

"Go directly! "

"OK! You are not too benzene. After you know a person's address, do you always remember it? "

"Some people remember. I forgot everything else. "

"Why did you forget? "

"Because I can't remember so many people who haven't been looking for him for a while. "

"How do I obtain the address in the phone number query system of Huashan school? "

"I shouted his name in the open room. When he heard it, he came to me and told me his address. "

Feng Qingyang asked a lot of questions similar to the sharp turn of the brain, and then Feng Qingyang said: "Do you understand the principle of directly finding the Port Based on the IP address? When you understand this truth, you will naturally make a layer-3 Switch ". After carefully recalling today's speech, Ling Hu Chong finally understands the same principle as that of layer-2 forwarding from MAC address to outbound port, layer-3 forwarding can also be directly mapped from an IP address to an outbound port. IP address routing can be learned through ARP, which also requires aging. In this way, in addition to the first packet to be forwarded between VLANs, the host route needs to be obtained through ARP, and other packets can be directly identified based on the IP address. The forwarding speed is much higher than the forwarding speed of the router. When I looked up, the wind was gone.

One year later, Linghu rushed down the cliff and successfully launched a route switch. Implements interconnection between VLANs and vrouters such as Songshan and heimu cliff. A layer-3 Switch adds a layer-3 switch function on the basis of a layer-2 switch. However, instead of simply adding a layer-2 switch to a router, a layer-3 Switch uses different forwarding mechanisms. Router forwarding adopts the longest matching method, which is complicated and usually implemented using software ,. The Routing Query of a layer-3 switch is for a stream. It uses the cache technology and is easily implemented using ASIC. Therefore, it can greatly reduce costs and achieve fast forwarding.

Many articles will mention the difference between a layer-3 Switch and a router. Generally, a layer-3 switch is fast and cheap. None of these are wrong, but the scenario is the aggregation layer. As we can see, in the aggregation layer, the layer-3 switch can be used to directly mount a host, because it can obtain its host route, so the layer-3 switch can be quickly searched; for hosts connected to multiple subnets through other routers, layer-3 switches have the same processing as routers, and the longest matching method is used to find the next hop, it is forwarded by the next hop router.

Therefore, the common networking mode is to use GSR on the backbone layer, and the aggregation layer uses a layer-3 switch. Of course, for a small man, you can also directly build a layer-3 Switch without GSR.

PS: It is said that this article was made by Huawei's talented fellow man. The original source is that I am not sure where to compare the two-layer interpretation of martial arts novels with the OSI structure.