Network equipment configuration and management-inter-VLAN routing to achieve inter-departmental communication 03/29 Update SLTechnology News&Howtos

Network equipment configuration and management-inter-VLAN routing to achieve inter-departmental communication

2025-03-29 Update From: SLTechnology News&Howtos shulou NAV: SLTechnology News&Howtos > Network Security >

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Theoretical study

Question 1: how many ways are there to implement the routing of layer 3 switches?

1) Virtual switching Interface (svi)

2) routing Interface (routed port)

3) layer 3 aggregation link (L3 Aggregate Link) interface

Question 2: describe the implementation principle of single-arm routing?

Single-arm routing is divided by vlan on a layer 2 switch, and then connects to an interface of the router through a trunk link (usually routing requires at least two interfaces to achieve routing function, but now only one interface is needed, just like an arm is working, so it is called single-arm routing) Through the configuration of subinterfaces and 802.1Q protocol encapsulation on the router, the one-to-one correspondence between vlan information and subnet is finally realized, that is, the routing function between vlan is realized.

What is the meaning of question 3:SVI? How to implement inter-VLAN routing?

The switch virtual interface (Switch Virtual Interface,SVI) represents a VLAN made up of switched ports (commonly known as VLAN interface) to facilitate routing and bridging in the system. A switch virtual interface corresponds to a VLAN. When you need to route traffic between virtual Lans or bridge the non-routable protocol between VLAN, and provide the connection between IP hosts to the switch, you need to configure the corresponding switch virtual interface for the corresponding virtual LAN. In fact, SVI refers to the so-called VLAN interface, but it is virtual and is used to connect the whole VLAN. Therefore, this kind of interface is usually called logical layer 3 interface, which is also layer 3 interface.

Layer 3 can be divided into vlan to set an address to vlan as a gateway to achieve inter-vlan routing.

You can also create vlan at layer 2 and create one-arm routing through virtual subinterfaces in layer 3 to realize inter-vlan routing.

Question 4: what is the difference between routing interfaces and SVI interfaces to implement routing

To put it bluntly, the svi interface is the vlan interface, which is equipped with ip, and then the layer 2 port is added. The previous equipment can not be equipped with ip directly on the port, so it uses the svi interface mode to configure ip to achieve layer 3 connection.

On the other hand, the routing interface is to set ip directly on the port to achieve routing.

Question 5: what are the types of VLAN for the switch?

1) Business vlan

2) connected vlan

3) manage vlan

Job task description

A company now has two departments, each with about 100 computers, all of which are located in the same subnet. Now it is found that the communication quality of the whole network is very poor. How to carry out network transformation to improve the quality of network communication?

Task implementation

Network topology design (paste the topology diagram of PT)

Scheme 1: SW1 is connected to the computer of department A, SW2 is connected to the computer of department B, two layer 2 switches are used for network access without any configuration, and the uplink lines of these two layer 2 switches are respectively connected to a VLAN of the RS switch, and the two VLAN of the RS are configured with IP addresses to realize the inter-VLAN routing function. The planning and configuration of this kind of network is suitable for the computers of An and B departments to connect to their respective switches relatively independently, and only the routing problem between the two departments needs to be solved.

Option 1 configuration:

RS#show run

Building configuration...

Current configuration: 1307 bytes

Version 12.2

No service timestamps log datetime msec

No service timestamps debug datetime msec

No service password-encryption

Hostname RS

Ip routing

Spanning-tree mode pvst

Interface FastEthernet0/1

(omit.)

Interface FastEthernet0/23

Switchport access vlan 2

Switchport mode access

Interface FastEthernet0/24

Switchport access vlan 3

Switchport mode access

Interface GigabitEthernet0/1

Interface GigabitEthernet0/2

Interface Vlan1

No ip address

Shutdown

Interface Vlan2

Ip address 192.168.1.254 255.255.255.0

Interface Vlan3

Ip address 192.168.2.254 255.255.255.0

Ip classless

Line con 0

Line aux 0

Line vty 0 4

End

Try and view the routes for RS

RS# show ip route

Codes: C-connected, S-static, I-IGRP, R-RIP, M-mobile, B-BGP

D-EIGRP, EX-EIGRP external, O-OSPF, IA-OSPF inter area

N1-OSPF NSSA external type 1, N2-OSPF NSSA external type 2

E1-OSPF external type 1, E2-OSPF external type 2, E-EGP

I-IS-IS, L1-IS-IS level-1, L2-IS-IS level-2, ia-IS-IS inter area

*-candidate default, U-per-user static route, o-ODR

P-periodic downloaded static route

Gateway of last resort is not set

C 192.168.1.0/24 is directly connected, Vlan2

C 192.168.2.0/24 is directly connected, Vlan3

Plan 2: if the computers of departments An and B are connected to the SW1 and SW2 switches respectively due to their geographical location, the two uplink lines of SW1 and SW2 need to be set as Trunk lines, and the RS switch adopts the mode of VTP domain to realize the function of extending VLAN, and then the routing function between the two VLAN is realized by configuring the IP address of each VLAN on the RS layer 3 switch.

Option 2 configuration:

RS#show run

Building configuration...

Current configuration: 1381 bytes

Version 12.2

No service timestamps log datetime msec

No service timestamps debug datetime msec

No service password-encryption

Hostname RS

Ip routing

Spanning-tree mode pvst

Interface FastEthernet0/1

(omit. )

Interface FastEthernet0/23

Switchport access vlan 2

Switchport trunk encapsulation dot1q

Switchport mode trunk

Interface FastEthernet0/24

Switchport access vlan 3

Switchport trunk encapsulation dot1q

Switchport mode trunk

Interface GigabitEthernet0/1

Interface GigabitEthernet0/2

Interface Vlan1

No ip address

Shutdown

Interface Vlan2

Ip address 192.168.1.254 255.255.255.0

Interface Vlan3

Ip address 192.168.2.254 255.255.255.0

Ip classless

Line con 0

Line aux 0

Line vty 0 4

End

Sw1

Sw1#show run

Building configuration...

Current configuration: 1091 bytes

Version 12.1

No service timestamps log datetime msec

No service timestamps debug datetime msec

No service password-encryption

Hostname Sw1

Spanning-tree mode pvst

Interface FastEthernet0/1

Switchport access vlan 2

Switchport mode access

Interface FastEthernet0/2

Switchport access vlan 3

Switchport mode access

Interface FastEthernet0/3

(omit. )

Interface FastEthernet0/24

Switchport mode trunk

Interface Vlan1

No ip address

Shutdown

Line con 0

Line vty 0 4

Line vty 5 15

End

Sw2

Sw2#show run

Building configuration...

Current configuration: 1091 bytes

Version 12.1

No service timestamps log datetime msec

No service timestamps debug datetime msec

No service password-encryption

Hostname Sw2

Spanning-tree mode pvst

Interface FastEthernet0/1

Switchport access vlan 2

Switchport mode access

Interface FastEthernet0/2

Switchport access vlan 3

Switchport mode access

Interface FastEthernet0/3

(omit. )

Interface FastEthernet0/24

Switchport mode trunk

Interface Vlan1

No ip address

Shutdown

Line con 0

Line vty 0 4

Line vty 5 15

End

Try and view the routes for RS

RS#show ip route

Codes: C-connected, S-static, I-IGRP, R-RIP, M-mobile, B-BGP

D-EIGRP, EX-EIGRP external, O-OSPF, IA-OSPF inter area

N1-OSPF NSSA external type 1, N2-OSPF NSSA external type 2

E1-OSPF external type 1, E2-OSPF external type 2, E-EGP

I-IS-IS, L1-IS-IS level-1, L2-IS-IS level-2, ia-IS-IS inter area

*-candidate default, U-per-user static route, o-ODR

P-periodic downloaded static route

Gateway of last resort is not set

C 192.168.1.0/24 is directly connected, Vlan2

C 192.168.2.0/24 is directly connected, Vlan3

If it is changed to layer 3 interface, how to implement it?

Show run

Building configuration...

Current configuration: 1317 bytes

Version 12.2

No service timestamps log datetime msec

No service timestamps debug datetime msec

No service password-encryption

Hostname RS

Ip routing

Spanning-tree mode pvst

Interface FastEthernet0/1

(omit. )

Interface FastEthernet0/23

No switchport

Ip address 192.168.1.254 255.255.255.0

Duplex auto

Speed auto

Interface FastEthernet0/24

No switchport

Ip address 192.168.2.254 255.255.255.0

Duplex auto

Speed auto

Interface GigabitEthernet0/1

Interface GigabitEthernet0/2

Interface Vlan1

No ip address

Shutdown

Interface Vlan2

No ip address

Interface Vlan3

No ip address

Ip classless

Line con 0

Line aux 0

Line vty 0 4

End

Work expansion

Extend the configuration of ACL

Because of the large investment in buying layer 3 switches, we can also use a more cost-saving method to achieve the above experiment, that is, using single-arm routing, so as long as we join a router, we can realize the routing between the VLAN of layer 2 switches.

Specific configuration:

R1#show run

Building configuration...

Current configuration: 594 bytes

Version 12.2

No service timestamps log datetime msec

No service timestamps debug datetime msec

No service password-encryption

Hostname R1

Interface FastEthernet0/0

No ip address

Duplex auto

Speed auto

Interface FastEthernet0/0.1

Encapsulation dot1Q 2

Ip address 192.168.1.254 255.255.255.0

Interface FastEthernet0/0.2

Encapsulation dot1Q 3

Ip address 192.168.2.254 255.255.255.0

Interface FastEthernet0/1

No ip address

Duplex auto

Speed auto

Shutdown

Ip classless

Line con 0

Line aux 0

Line vty 0 4

End

Switch

Show run

Building configuration...

Current configuration: 1094 bytes

Version 12.1

No service timestamps log datetime msec

No service timestamps debug datetime msec

No service password-encryption

Hostname Switch

Spanning-tree mode pvst

Interface FastEthernet0/1

Switchport access vlan 2

Switchport mode access

Interface FastEthernet0/2

Switchport access vlan 3

Switchport mode access

Interface FastEthernet0/3

(omit. )

Interface FastEthernet0/24

Switchport mode trunk

Interface Vlan1

No ip address

Shutdown

Line con 0

Line vty 0 4

Line vty 5 15

End

Think about the question:

Question 1: what is the difference between router-on-a-stick routing and inter-VLAN routing on layer 3 switches?

In the case of large traffic, single-arm routing will bring a lot of load to the router.

The inter-VLAN routing of the layer 3 switch is completed by the layer 3 forwarding engine of the switch, and its performance depends on the backplane forwarding rate of the switch. Note, because the general layer 3 switch can easily achieve line-speed forwarding on multiple ports (note: not all ports forward at the same time), it can achieve good performance, the inter-VLAN traffic does not have to pass through the router, and the network delay and jitter are very small. At the same time, it also greatly reduces the load of the upper access router.

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