Dell PowerConnect 5548 User Guide - Page 463

Ingress filtering is always enabled on Trunk-mode ports. Incoming frames will undergo ingress filtering, and if correctly tagged, (tagged with a VID of one of the VLANs to which the port currently belongs) are admitted. The default PVID is 1 (the default VLAN). If another VID is configured as the port's PVID, and the corresponding VLAN is deleted from the port or from the system, the port's PVID reverts to 1, meaning that the port is made a member of the default VLAN. Setting a trunk-port's PVID to 4095 limits traffic to tagged frames. Incoming untagged frames are silently discarded, and no frames are sent untagged. Trunk-mode ports are intended for switch-to-switch links, where traffic is usually tagged. • General Ports Ports set to General mode may be members of multiple VLANs. Each of these VLANs may be configured to be tagged or untagged. This setting applies to transmitted frames. Incoming untagged frames are classified into the VLAN whose VID is the currently configured PVID. Ingress filtering may be disabled on General ports. Ingress filtering is enabled by default. • Promiscuous Ports A promiscuous port can communicate with all ports of the same Private VLAN (PVLAN), including the isolated ports of the same PVLAN. • Isolated An isolated port has complete Layer 2 isolation from the other ports within the same PVLAN, but not from the promiscuous ports. Isolated ports can communicate with promiscuous ports. In the factory default configuration, all ports are designated as Access ports, and are associated with the default VLAN. Dell PowerConnect 55xx Systems User Guide 463