44 | Rapier Switch User Guide |
whether or not they are VLAN tagged. The parameters for each port’s Ingress Rules can be configured using the command:
SET SWITCH
The ACCEPTABLE parameter sets the Acceptable Frame Types parameter, in the Ingress Rules, which controls reception of
The INFILTERING parameter enables or disables Ingress Filtering of frames admitted according to the ACCEPTABLE parameter, on the specified ports. Each port on the switch belongs to one or more VLANs. If INFILTERING is set to ON, Ingress Filtering is enabled: any frame received on a specified port is only admitted if the port belongs to the VLAN with which the frame is associated. Conversely, any frame received on the port is discarded if the port does not belong to the VLAN with which the frame is associated. Untagged frames admitted by the ACCEPTABLE parameter are admitted, since they have the numerical VLAN Identifier (VID) of the VLAN for which the port in an untagged member. If OFF is specified, Ingress Filtering is disabled, and no frames are discarded by this part of the Ingress Rules. The default setting is OFF.
To display the current Ingress Rules (Figure 8 on page 28), use the command:
SHOW SWITCH
The Learning Process
The Learning Process uses an adaptive learning algorithm, sometimes called backward learning, to discover the location of each station on the extended LAN.
All frames admitted by the Ingress Rules on any port are passed on to the Forwarding Process if they are for destinations within the same VLAN. Frames destined for other VLANs are passed to the layer three protocol, for instance IP. For every frame admitted, the frame’s source MAC address and numerical VLAN Identifier (VID) are compared with entries in the Forwarding Database for the VLAN (also known as a MAC address table, or a forwarding table) maintained by the switch. The Forwarding Database contains one entry for every unique station MAC address the switch knows in each VLAN.
If the frame’s source address is not already in the Forwarding Database for the VLAN, the address is added and an ageing timer for that entry is started. If the frame’s source address is already in the Forwarding Database, the ageing timer for that entry is restarted. By default, switch learning is enabled, and it can be disabled or enabled using the commands:
DISABLE SWITCH LEARNING
Rapier Switch Software Release 2.2.1