Allied Telesis Rapier Switch - Manual (Page 50)

50 Rapier Switch Software Reference
Software Release 2.5.1
C613-02025-00 REV B
For each VLAN, the destination MAC address of a frame to be forwarded is
checked against the Forwarding Database. If there is no entry for the
destination address and VLAN, the frame is transmitted on all ports in the
VLAN that are in the ‘Forwarding’ or ‘Disabled’ states, except the port on
which the frame was received. This process is referred to as flooding. If an entry
is found in the Forwarding Database, but the entry is not marked as
‘Forwarding’ or the entry points to the same port the frame was received on,
the frame is discarded. Otherwise, the frame is transmitted on the port
specified by the entry in the Forwarding Database.
A dynamic entry is automatically deleted from the Forwarding Database when
its ageing timer expires.
The Egress Rules
Once the Forwarding Process has determined which ports and transmission
queues to forward a frame from, the Egress Rules for each port determine
whether or not the outgoing frame is VLAN-tagged with its numerical VLAN
Identifier (VID). (See “Virtual Local Area Networks (VLANs)” on page 38).
When a port is added to a VLAN, it is configured to transmit either untagged
or VLAN tagged packets, using the command:
ADD VLAN={vlanname|1..4094} PORT={port-list|ALL}
[FRAME={TAGGED|UNTAGGED}]
This setting can be changed for a port which is already part of a VLAN, using
the command:
SET VLAN={vlanname|1..4094} PORT={port-list|ALL}
FRAME={UNTAGGED|TAGGED}
Quality of Service
The switch hardware has a number of Quality of Service (QOS) egress queues
that can be used to give priority to the transmission of some frames over other
frames on the basis of their user priority tagging. The user priority field in an
incoming frame (with value 0 to 7) determines which of the eight priority levels
the frame is allocated. When a frame is forwarded, it is sent to a QOS egress
queue on the port determined by the mapping of priority levels to QOS egress
queues. All frames in the first QOS queue are sent before any frames in the
second QOS egress queue, and so on, until frames in the last QOS egress queue,
which are only sent when there are no frames waiting to be sent in any of the
higher QOS egress queues.
Source This parameter is either “static” (indicating the filter is a static
filter) or “learned” (indicating the filter is present either
because it has been added with the LEARN parameter of the
SET SWITCH PORT command, or has been dynamically learned
during normal intrusion detection operation).
Table 12: Parameters in the output of the SHOW SWITCH FILTER command
Parameter Meaning