RuggedCom RS400 Egress Rules, Forbidden Ports List, VLAN-aware and VLAN-unaware operation modes

VLANs

Frame received		Priority	Tagged
This doesn’t	Untagged
		Tagged
depend on ingress			(valid VID)
		(VID=0)
port ‘s VLAN configuration
parameters
VLAN the frame associated with	PVID	PVID	VID in the tag

Frame	dropped	due	to	its	No	No	No
tagged/untagged format
Frame dropped, if associated with VLAN					N/A	N/A	Yes
not configured (or learned) in the switch
Frame dropped, if ingress port is not a					N/A	N/A	No
member of the VLAN the frame
associated with

Egress Rules

These are the VLAN egress rules, i.e. the rules applied to all frames when they are transmitted by the switch:

Frame sent			On other
	On egress port’s native			VLAN
					Port is NOT
Egress port	VLAN	Port is member
					member of the
type		of the VLAN
					VLAN
	According to the egress
Edge		N/A (frame is dropped)
Trunk	port’s “PVID Format”	Tagged			dropped
	parameter

6.1.7 Forbidden Ports List

Each VLAN can be configured to exclude ports from membership in the VLAN.

6.1.8 VLAN-aware and VLAN-unaware operation modes

The native operation mode for an IEEE 802.1Q compliant switch is VLAN-aware. Even if a specific network architecture doesn’t use VLANs, ROSTM default VLAN settings allow the switch still to operate in a VLAN-aware mode while providing functionality required for almost any network application. However, the IEEE 802.1Q standard defines a set of rules that must be followed by all VLAN-aware switches, for example:

•Valid VID range is 1 to 4094 (VID=0 and VID=4095 are invalid)

•Each frame ingressing a VLAN-aware switch is associated with a valid VID

•Each frame egressing a VLAN-aware switch is either untagged or tagged with a valid VID (this means priority-tagged frames with VID=0 are never sent out by a VLAN-aware switch)

It turns out that some applications have requirements conflicting with the IEEE 802.1Q native mode of operation (e.g. some applications explicitly require priority-tagged frames to be received by end devices).

RS400 171 ROS™ v3.5