Two ways to communicate with each other in different VLANs

(Single-arm routing, three-layer switching)

test Environment: second floor of Eastern suburbs third room

Test Equipment: Catalyst 2950-24 (SW3)

Cisco 2611 (R2)

Catalyst 3750 SERIES ( with two SD interfaces,S8----sw-2l)

Real Machine (PC5,PC6).

Purpose of Test:

1 , the communication between different VLANs is realized through one-arm routing

2 , the communication between different VLANs is realized through the three-layer switching routing function.

Network topology diagram:

1 , single-arm routing realizes different VLAN interoperability Test network topology diagram

2 , three-layer switching realizes different VLAN Interoperability Experiment Network topology diagram

Experimental steps:

Single-arm routing for different VLAN interoperability test steps

One, the specific configuration of the switch SW3 (main configuration VLAN and Trunk interface)

1 , create VLANson SW3 ,vlan200,vlan300, the names are Caiwu,Xiaoshou, Gongcheng. (Creating VLANs can be configured either in VLAN database or in global mode, this experiment is configured in VLAN database )

2 , in global mode, F0/1 – Port 5 is divided into vlan ,F0/6– Ten ports are divided into VLAN F0/11 – The ports are divided into VLANs and are all configured in access mode.

3 , using show VLAN to display VLAN configuration information for SW3 , you can see that the configuration is correct)

4 , if the switch through the router to achieve the communication between the VLAN , the port that connects the switch needs to be configured in Trunk mode, only trunk line can make VLAN pass.

Second, the specific configuration of router R2 (by configuring the router sub-interface encapsulated as a gateway for each VLAN )

1 , the subinterface is configured on the port of the router (R2) and the switch (SW3), and the IP address of each subinterface is the gateway address of each VLAN (which can also be understood as the next hop address). The 802.1Q Protocol (switch generic encapsulation mode) is encapsulated on the sub-interface. The ISL protocol (Cisco Private Protocol, incompatible with 802.1Q) can also be encapsulated.

2 pc5 and pc6 are connected to the switch sw3 F0/6 and f0/1 , and then configure pc5 ip address Span lang= "en-US" >192.168.2.1/24 , the gateway is 192.168.2.254 . pc6 ip address 192.168.1.1 , Gateway to 192.168.1.254 . Then use pc5 Ping PC6 to see if you can ping pass.

Three-layer switching for different VLAN interoperability Experiments

First, using the VTP protocol to achieve the consistency of VLAN configuration.

Note: The f0/24 Port of theSW3 is already set to trunk mode, and the interface of the Cisco Catalyst 3750 switch is dynamically negotiated by default, and both parties actively negotiate trunk link. You can also set them manually.

1 , configure SW3 to VTP server mode, and the domain name is benet.com. Provides VTP advertisements for other switches to achieve the consistency of VLAN mates.

2 , the domain name of the configuration layer three switch sw-2l(R8) is benet.com, and the mode is client mode. Accepts VLAN advertisements for SW3 .

3 , as can be seen from the figure below,sw-2l has learned the sw-2l VTP notification information. (Note: Do not learn port partitioning)

4 , configure the start-up routing feature on the layer three switch sw-2l (the routing feature must be enabled, or the three-layer switch will function equivalent to the two-tier switch).

5 , configure the IP addresses of each VLAN on the layer three switch s2-2l , which is the gateway for each VLAN . (a layer three switch supports routing between each VLAN equivalent to the IP address configured on a single-arm route, and the configuration method is the same as configuring the VLAN1(Managed) IP address command).

6 , when configured, you can view direct-attached routing information through the show ip route .

7 , view the fib table for layer three switch sw-2l (thefib table is similar to the routing table, and contains a mirror of the forwarding information in the routing table. When the network topology changes, the routing table is updated, and the FIB changes as well. The FIB contains the next hop address information, which is also based on the information in the routing table. )

8 , view the Neighbor relationship table.

9 pc5 and pc6 are connected to the switch sw3 F0/6 and f0/1 , and then configure pc5 ip address Span lang= "en-US" >192.168.2.1/24 , the gateway is 192.168.2.254 . pc6 ip address 192.168.1.1 , Gateway to 192.168.1.254 . Then use pc5 Ping PC6 to see if you can ping pass.

experiment summary: vlan between two ways, one through the single-arm routing implementation, the other is through the three-layer switching routing function, can be said that different Communication between VLAN must pass through the routing function to achieve communication. Second, there is a need to configure the next-hop address (gateway) between different network segments to communicate. So when to use one-arm routing, when to choose the three-layer exchange it. One-arm routing is not extensible, why so, if the vlan the number of increasing, flow through the router and switch link between the traffic also become very large, this link is also a bottleneck of the entire network, This is true even if the bandwidth of your network is fast. Therefore, when the network is growing, the division of vlan is increasing, it is necessary to configure the three-layer switch routing function, the implementation of different vlan Communication between the three-layer switch's data table throughput is typically millions of pps , while the throughput of a traditional router is only 10kpps~1mpps , The second layer three switch is the hardware to exchange and route the selection of packets, the throughput is certainly large, or even close to the line speed. The router simply switches and routes the packets through the virtual subinterface, not the hardware implementation, and the throughput becomes smaller.

In a word: three layer switching technology in the third layer to achieve high-speed data packet forwarding, so as to solve the traditional router slow, responsible for the network bottleneck caused by the problem.

From for notes (Wiz)

Two ways to communicate with each other in different VLANs