Cabletron-systems 2000 User Manual download pdf (Page 84)

The SmartSwitch 2000 Chassis View

2-62 Managing the Hub

When 802.1Q is implemented for a SmartSwitch 2000 that has an HSIM-A6DP

installed, each LEC will be represented as an individual port which can be easily

assigned membership in a VLAN.

Once VLANs have been conÞgured and activated, all frames with unknown

destination addresses (including broadcast, unknown multicast, and unknown

unicast frames) will be contained within the VLAN of their origin. The switchÕs

Filtering Database tracks the associations between MAC addresses, VLAN

eligibilities, and port numbers, and is used to make forwarding decisions for

frames. All VLANs share a single Spanning Tree.

Ingress List Operation

A portÕs ingress list speciÞes the VLAN with which received frames will be

associated. The switchÕs Filtering Database tracks the associations between VLAN

eligibilities, MAC addresses, and port numbers.

Untagged frames received by an 802.1Q switch port are classiÞed according to the

VLAN membership of the port that receives the frame.

Tagged frames received by an 802.1Q switch port are classiÞed according to the

VLAN indicated in their tag header. A port may receive a tagged frame that

speciÞes a VLAN other than the one assigned to the port.

Egress List Operation

Each portÕs egress list speciÞes which VLANs are associated with the port, and

speciÞes what type of frame (tagged or untagged) to transmit for each particular

VLAN on a port. This information may be statically deÞned by the user, or

dynamically learned and maintained by the switchÕs Filtering Database.

If a port receives a tagged frame that speciÞes a VLAN other than the one

assigned to the port, the switch will dynamically associate that frameÕs source

address and VLAN with the port (i.e., add that frameÕs VLAN to the receiving

NOTE

When 802.1Q mode is initially activated on a device, all ports are associated with the

Default VLAN (VLAN ID 1). If a VLAN ID has not been assigned to a particular port

on an 802.1Q switch, any frames received from that port will be classiÞed as belonging to

the Default VLAN.

NOTE

For SmartSwitch 2000 Þrmware version 4.00.08 and above, the number of LECs

supported by the HSIM-A6DP in 802.1Q mode is limited to 32.

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Cabletron-systems 2000 User Manual Page 84