Web Smart Switch User's Manual

User Manual

Publication date: January, 2005

Revision A1

Ingress Rule:

Each packet received by a VLAN-aware bri dge will be classi fied to a VLAN.

The classification rule is described as follows.

1. If the VID of the packet is null VID (VID=0)or this packet is an untagged packet:

If there are still some other ways(e.g. protocol, MAC address, application, IP-

subnet, etc.) to classify the incoming packets beside port-based classification in

implement and these approaches can offer non-zero VID, then, use the value of VID

offered by other classifications for VLAN’s classification.

If there is only port-based classification in implement or other classification

approaches cannot offer non-zero VID for the incoming packets, then assign the

PVID to the incoming packets as VID for the classification of the VLAN group.

2. If the VID is not a null VID (VID≠0), then use the value to classify the VLAN group.

E g re ss Ru l e :

An e gress li st i s used to m ake the tagging and forwarding deci sion on an

outgoing port. It specifies the VLANs whose packets can be transmitted out and

specifies if the packet should be tagged or not. It can be configured for port’s VLAN

membership, and tagged or untagged for a transmitted packet. When a packet is

transmitted out, the VLAN bridge checks the port’s egress list. If the VLAN of the

packet is on the egress list of the port on which the packet transmits out, the packet

will be transmitted with the pri ori ty accordingly. If enabled, an egress port will

tran sm i t ou t a tagg ed p acket if the p ort i s connected to a 802.1Q-compli ant devi ce .

If an egress port is connected to a non-802.1Q device or an end station, VLAN

bridge must transmit out an untagged packet, i.e. the tag has been stripped off in an

egress port. Egress rule can be set by per port.

Independent VLAN Learning (IVL):

It specifies the mode how to learn MAC address. For a specifi ed VLAN, it will

use an independent filtering database (FID) to learn or look up the membership

information of the VLAN and decide where to go.

Shared VLAN Learning (SVL):

It specifies the mode how to learn MAC address. In this mode, some VLAN

or all VLANs use the same filtering database storing the membership information of

the VLAN to learn or look up the membership information of the VLAN. In 16 Gigabit

Web Smart Switch, you can choose a VID for sharing filtering database in Shared

VID field if you wish to use the existed filtering database. For a specified VLAN,

when a MAC address is learned by a switch, VLAN will use this formation to make

forwarding decision.

Filtering Database:

Referred to as FID. It can provide the information where the packet will be

sent to. Filtering database will supply the outgoing port according to the request

from forwarding process with VID and DA. When a packet is received, if it has a

non-zero VID, then FID will offer the associated outgoing ports information to the

packet.

In SVL, VLANs use the same Filtering Database. In IVL, VLANs use different

FIDs. Any VID can be assigned to the same FID by administrator.