Switch Overview¶
This document is an overview of how the switch operates and its capabilities.
See also
For instructions on how to configure the switch ports, see Configuring the Switch Ports.
Warning
The switch ports do not support the Spanning Tree Protocol (STP). Two or more ports connected to another Layer 2 switch, or connected to 2 or more different interconnected switches, could create a flooding loop between the switches. This can cause the router to stop functioning until the loop is resolved.
Warning
The switch is limited to a total maximum of 128 separate VLANs.
Interface Links¶
The four LAN ports on the Netgate 3100 are connected internally to a switch.
In addition to the four physical ports there is also an internal switch port
(Port 5) which acts as an uplink, and the mvneta1 interface which is the
corresponding operating system interface for the switch uplink.
The internal uplink port operates at 2.5 Gbps and connects the switch to the
SoC. From the perspective of the operating system, the only port is the
mvneta1 interface which also runs at the same 2.5 Gbps speed.
Port Mode¶
By default, the switch is in Port VLAN Mode. The four LAN ports are configured on the same network which feeds into the LAN interface. These four switch ports are customizable and each can be configured to act as an independent switches or in groups.
In Port VLAN Mode, any and all VLAN tags are allowed on all ports. No VLAN tags are added or removed. Think of it as a dummy switch that retains VLAN tags on frames, if present. This mode is useful when there are numerous VLANs on a network and the goal is to physically segment the switch, while allowing the same VLANs on all segments of the switch.
In Port VLAN Mode, rather than specifying which interfaces are associated to a VLAN, the configuration can specify which physical ports form a switch.
802.1q VLAN Mode¶
It is also possible to enable 802.1q VLAN mode instead of the default port mode.
Using VLANs, these four switch ports are customizable and each can be configured to act as independent interfaces. For example, all of these configurations are possible:
LAN1-4 dedicated as a LAN switch
LAN1-2 configured as a switch for LAN A and LAN3-4 configured as a switch for LAN B
LAN1-4 configured as individual network interfaces
LAN1-2 configured as a switch for LAN A, LAN3 configured for WAN B, and LAN4 configured for WAN C.
Each of the switch ports (LAN1-4 and Port 5) are VLAN aware interfaces. They are capable of functioning as a standard access or trunk port:
- Access Port:
Adds a VLAN tag to inbound untagged traffic
- Trunk Port:
Allows tagged traffic containing specified VLAN IDs
When switching from Port VLAN mode to 802.1q VLAN mode there is no default configuration. See Configuring the Switch Ports for details on configuring this mode.