Comprehensive Analysis of Cisco switch interface mode

There are still many things worth learning about Cisco switches. Here we mainly introduce the Cisco switch interface mode. In a Cisco switch network, there are four main types of interfaces in the LAN that are ultimately stable: access/trunk/multi/dot1q-tunnel.

1. access: it is mainly used to access terminal devices, such as PCs, servers, and print servers.

2. trunk: it is mainly used to connect to other switches, so that multiple VLANs can be carried online.

3. multi: It carries multiple VLANs in a single line, but unlike trunk, it does not label the bearer data. It is mainly used to access servers that support multiple VLANs or some network analysis devices. Currently, this type of interface is basically not used. This type of interface is basically not supported in the network device of the Cisco switch.

4. dot1q-tunnel: Used in the Q-in-Q tunnel configuration. The Cisco switch network equipment supports dynamic negotiation of the working status of the port, which provides some convenience for the implementation of the network equipment, but it is not recommended to use dynamic mode ). The dynamic routing protocol for Cisco switches evolved from the original DISLCisco switch private Protocol) to the DTP public protocol ). According to the Implementation of Dynamic protocols, Cisco switch network device interfaces are divided into the following modes:

1. switchport mode access: forces an interface to become an access interface, and can negotiate with the other party to induce the other party to become an access mode.

2. switchport mode dynamic desirable: It is possible to negotiate with the peer interface to become a Trunk interface. If the neighbor interface mode is one of Trunk/desirable/auto, the interface will become a trunk interface. If the trunk mode cannot be formed, it works in access mode. This mode is the default mode of the current switch.

3. switchport mode dynamic auto: the Trunk interface is changed only when the neighbor switch actively negotiates with itself. Therefore, it is a passive mode. When the neighbor interface is Trunk/desirable, to be a Trunk. If the trunk mode cannot be formed, it works in access mode.

4. switchport mode trunk: forces the interface to become the Trunk interface and actively induces the other party to become the Trunk mode. Therefore, when the neighbor switch interface is trunk/desirable/auto, it will become the Trunk interface.

5. switchport nonegotiate: strictly speaking, this is not an interface mode. Its function is to prevent the switch interface from sending DTP data packets. It must be used with switchport mode trunk or switchport mode access.

6. switchport mode dot1q-tunnel: configure the switch interface as a tunnel interface non-Trunk) to form an asymmetric link with the Trunk interface of the User Switch.