RUGGEDCOM RSG2488
User Guide
Chapter 5
Setup and Configuration
Ingress and Egress Rules
113
Trunk ports are part of the network and carry traffic for all VLANs between switches. Trunk ports are automatically
members of all VLANs configured in the switch.
The switch can 'pass through' traffic, forwarding frames received on one trunk port out of another trunk port. The
trunk ports must be members of all VLANs that the 'pass through' traffic is part of, even if none of those VLANs
are used on edge ports.
Frames transmitted out of the port on all VLANs other than the port's native VLAN are always sent tagged.
NOTE
It may be desirable to manually restrict the traffic on the trunk to a specific group of VLANs. For
example, when the trunk connects to a device, such as a Layer 3 router, that supports a subset of the
available LANs. To prevent the trunk port from being a member of the VLAN, include it in the VLAN's
Forbidden Ports list.
For more information about the Forbidden Ports list, refer to
Section 5.1.1.6, “Forbidden Ports List”
.
Port Type
VLANs Supported
PVID Format
Usage
Untagged
All frames are sent and received without the need for VLAN tags.
Edge
1 (Native)
Configured
Tagged
VLAN traffic domains are enforced on a single VLAN.
Trunk
All Configured
Tagged or Untagged
Switch-to-Switch Connections
: VLANs must be manually created
and administered.
Multiple-VLAN End Devices
: Implement connections to end devices
that support multiple VLANs at the same time.
Section 5.1.1.5
Ingress and Egress Rules
Ingress and egress rules determine how traffic is received and transmitted by the switch.
Ingress rules are applied as follows to all frame when they are received by the switch:
Frame Received
a
Untagged
Priority Tagged
(VID = 0)
Tagged (Valid VID)
VLAN ID associated with the frame
PVID
PVID
VID in the Tag
Frame dropped due to its tagged/untagged format
No
No
No
Frame dropped if the frame associated with the VLAN is not
configured (or learned) in the switch
Yes
Frame dropped if the ingress port is not a member of the VLAN the
frame is associated with
No
a
Does not depend on the ingress port's VLAN configuration parameters.
Egress rules are applied as follows to all frames when they are transmitted by the switch.
On Other VLAN
Egress Port Type
On Egress Port's Native VLAN
Port Is a Member Of the VLAN
Port Is Not a
Member Of the VLAN
Edge
Dropped
Trunk
According to the egress port's
PVID Format
parameter
Tagged
Dropped