Three layer switching ①

Park concept ：

         Campus network ： factory , The government authority , Office buildings , The network built by these public places such as parks to realize data exchange can be called Park Network , Different campus networks have different priorities .

Wireless network ：

         The connection of wireless network depends on wireless devices that can transmit and receive wireless signals , These devices also need to be connected to the network through wired access . And one of AP It is a wireless access point ,WLAN For WLAN （ Broadly speaking, it refers to radio waves , laser , Infrared, etc. to replace part or all of the transmission media of the wired LAN ）

Wireless network defects ：

① Poor penetration of wireless signals
        Wireless uses Ethernet Technology （ Frequency division ）, The civil wireless network uses low-frequency network segment for data transmission , Low frequency data network segment has congenital defects, poor penetration and other problems .

② Wireless network transmission rate is related to signal strength , And the transmission rate refers to the bidirectional rate

        Limited network signal transmission rate =（ bandwidth /8）*86.66%, The transmission rate of wireless network is bidirectional transmission rate （ Including upload and download rates ）, Information transmission rate =[（ bandwidth /8）/2]*86.66%

③ Wireless network transmission efficiency is low , Less efficient

         At this time, the physical devices in the limited network are introduced ： A hub , The reason why hubs are not popular is that hubs will generate conflict domains , The hub's solution to the conflict domain ：CSMA/CD（ Carrier sense multiple access / Conflict detection technology ）, To put it simply, check the conflict query and timer wait （ Finding a signal conflict will set a waiting timer for this signal , After waiting for the timer to reset , Reprocess information ）, however CSMA/CD The flaw is the delay of the signal （ Unable to quickly handle the exchange of information ）.

         And WLAN is also equivalent to being in the same conflict domain （ When connecting the interface ）, Wireless technology is used to solve conflicts CSMA/CA（ Carrier sense multiple access / Conflict avoidance techniques ）,CA Compared with CD A lower .

         The wireless device cannot check the cause of the conflict ： Because the dynamic range of wireless signal strength is very large , Often the received signal strength may be much less than the sent signal strength , It makes it difficult to check conflicts （ It can enhance hardware performance and improve strength ）

CA Technology to avoid conflict ：

        ① When no message is sent within the listening range , It doesn't send signals directly , Instead, I will first set myself a random timer

        ②CSMA/CA The technology adopts stop flow control （ After a message is sent, it must be received from the opposite end ACK After the confirmation , Will continue to send messages ）

Three layer switch level concept ：

         Access layer ： The main purpose is to connect all terminal devices to the network , And provide access port （ Generally, layer-2 switches are used , rely on mac Address table realizes two layer forwarding ）

         Convergence layer ： The main purpose is Gather the traffic collected by the access layer , Generally, three-tier switches are used （ The layer-3 switch has a layer-2 interface similar to that used by ordinary layer-2 switches, and also has a layer-3 interface similar to that used by routers or computers . The biggest difference between layer 2 interface and layer 3 interface is whether there is ip Address . The layer-3 switch can pass through MAC Address table realizes two layer forwarding , Three layer forwarding can also be realized through routing table ）

         Core layer ： The main function is to complete the rapid forwarding of data between public and private networks

redundancy （ Backup ）：

         The core of the three-tier architecture of enterprise network is redundancy （ Backup ）, A real three-tier architecture must have redundancy , The redundancy of the three-tier architecture is mainly divided into four types ：

        ① Line redundancy ,② Equipment redundancy ,③ Gateway redundancy ,④UPS redundancy （UPS： Uninterruptible power supply , Ensure that the power supply of enterprise equipment reaches 99.9999% The usability of ）

        Generally, what we can do is line redundancy , Equipment redundancy and gateway redundancy

VLAN label

introduce ：

        802.1Q Standard design VLAN The label of is composed of four bytes , It includes 12 Bit VID, Used to distinguish the different VLAN Traffic , And add this tag to the Ethernet two frame source MAC Address fields and TYPE Between fields

        IEEE802.1Q The standard stipulates , Frames with labels are called raggedd frame /802.1Q frame , Frames without labels are called untagged frame

         According to this feature , The link between the switch and the computer is called ACCESS link , also ACCESS The interface in the switch in the link is ACCESS Interface .ACCESS The link can only pass through untagged frame , And these frames can only belong to the same vlan, Computers can only recognize untagged frame

        The link between switches is called TRUNK Interface ,TRUNK The interfaces at both ends of the link are called TRUNK Interface .TRUNK The link is allowed to pass through tagged frame , And these frames can belong to multiple vlan

Huawei's VLAN surface ：

Link Type （ Interface type ）：    

        ①trunk Interface ,②access Interface ,③hybrid Hybrid interface

        Huawei equipment , All interfaces default to hybrid type

PVID（ Interface VID）： 

         Each interface of Huawei needs to be configured with one PVID, That is, the interface belongs to VID. All interfaces PVID The default is 1,

PVID The range is from 0~2^20

VLAN List（ VLAN allow list ）： 

        VLAN List： Allow the interface to pass through vlan list , If PVID The same information will follow list Forward , and PVID Different information will be discarded .

        VLAN List There are two pass types in the ：U Means no label untagged adopt ,T For labeled tagged adopt

         All data enters the Huawei switch through the Huawei interface , All interfaces must be marked PVID The label of , That is to say All data inside the switch is labeled

ACCESS label ：

         ① When ACCESS The interface received a message from the link untagged After the frame , Swap opportunities add... To this frame VID Interface for PVID by tag, Then judge the frame label VID Whether it is in the Allow list , If you're here, you'll get tagged Forward frames , If it is not in the Allow list, it will be directly discarded

        ② When tagged Frames arrive from other ports of the switch ACCESS After a mouth , The exchange opportunity checks the... In this frame tagged Of VID Whether it is in the Allow list , If it is in the Allow list, it will split tagged The tag is then forwarded from the link , If it is not in the list, it will be discarded directly

        ③ If ACCESS The interface received a message from the link tagged After the frame , will Directly view the tag of this data VID Whether in your own list , If so, forward , If not, discard

TRUNK label ：

        ① When TURNK The interface received a message from the link untagged frame , The switch first adds a... To the data frame VID by PVID Of tagged, And then based on VID View the Allow List , If so, forward , If not, discard

        ② When taggged Frames arrive from other ports of the switch TRUNK After a mouth , be The exchange opportunity checks the... In this frame tag Of VID Whether it is in the Allow list , If it is, it will be stripped tag Then forward from the link , If not in the list, discard

         If VID and TRUNK Interface PVID Phase at the same time , The label needs to be stripped when transferring out , If PVID inequality , Then directly transfer out

        ③ If TRUNK The interface received a message from the link tagged After the frame , The tag of this data will be directly viewed VID Whether you are in your allow list , If so, forward , If not, discard

HYBIRD label ：

         Huawei's HYBIRD The label can be modified PVID,VID,VLAN list To decide whether to forward , And whether to carry the tag when forwarding

The permissions of three tags ：

        ACCESS/TRUNK/HYBRID These three types of interfaces are in the custom forwarding table （vlan list） The modification permissions are different .

ACCESS Modify permission of interface ：

        ACCESS type You can modify PVID, You can also modify the permission list , The export mode can only be non encapsulation

        stay VLAN list In the Allow List ,access An interface can only have one VLAN ID, And it has to be with PVID identical

TRUNK Modify permission of interface ：

        TRUNK type You can modify PVID, You can also modify the permission list , The Allow list can be set to multiple VID, The export mode can be encapsulated / No encapsulation

        TRUNK Allow list for There can only be one VID, And this VID It's not fixed （ Not necessarily with PVID identical ）, also In the Allow list, this VID For fixing without labels （ In addition to this VID, Other VID All need to be labeled for transmission ）    

HYBRID Modify permission of interface ：

        HYBRID type You can modify PVID, You can also modify the permission list , The Allow list can be set to multiple VID, The export method can also be modified

        HYBRID It can be modified by PVID,VID And export methods to modify vlan list

To configure ：

① establish VLAN：

[Huawei]vlan  2
    # establish VLAN 2

[Huawei]vlan batch 4 to 100
    # Batch creation VLAN

[Huawei]undo vlan batch 4 to 10
    # Batch deletion VLAN

② Put the interface into VLAN：

① Single interface partition VLAN
[sw1-GigabitEthernet0/0/1]port default vlan 2

② The interface group is divided into the same VLAN
[sw1]port-group group-member GigabitEthernet 0/0/3 GigabitEthernet 0/0/4
[sw1-port-group] 
    # Create an interface group 
[sw1-port-group] port default vlan 2   
    # Define the interface group VLAN

③ Configure interfaces and trunk roads ：

① Single interface defines the type of trunk road 
[sw1-GigabitEthernet0/0/1]port link-type access 

② Trunk road type of Interface Group 
[sw1-port-group] port link-type access 

④ Configure the router VLAN Routing between

// A subinterface , A virtual interface （ Logically, a physical interface is divided into multiple virtual sub interfaces ）
[r1-GigabitEthernet0/0/2.1]ip address 192.168.1.1 24
[r1-GigabitEthernet0/0/2.1]dot1q termination vid 2
[r1-GigabitEthernet0/0/2.1]arp broadcast enable 
    //  Open the sub connection ARP Broadcast request response