Switch Port Working Mode

Generally, there are three types: Access, Multi, and Trunk. Trunk-mode ports are used for switches and switches, switches and routers, and mostly for cascading network devices. Access is mostly used in Access layer, also called Access mode. It mainly refers to static port access. In a cisco network, there are four main types of interfaces in which the switch is eventually stable in the LAN: 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. It is basically not supported in cisco network devices.
 
4. dot1q-tunnel: Used in the Q-in-Q tunnel configuration.
 
 
 
The Cisco network device supports dynamic negotiation of the working status of the port, which provides some convenience for the implementation of the network device (but dynamic mode is not recommended ). The cisco dynamic negotiation protocol evolved from the initial DISL (Cisco private Protocol) to DTP (Public protocol ). According to the Implementation of Dynamic protocols, Cisco 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.