Cabletron Systems CSX1200, CSX1000 manual Bridge Mode of Operation Background Information

CONFIGURING ADVANCED BRIDGING

Bridge Mode of Operation

BRIDGE MODE OF OPERATION BACKGROUND INFORMATION

Selecting the bridge mode of operation allows you to determine the forwarding method that the bridge will use to distribute LAN packets to the remote sites and to the LAN ports of the system. The two possible modes of operation are the Unrestricted Bridge Mode and the Restricted Bridge Mode.

Note: If the mode of operation is changed, any previously defined filters will be deleted. Any previously defined protocol definitions will remain unchanged.

The following two sections provide further details for each bridge mode of operation.

UNRESTRICTED BRIDGE MODE

In general, Unrestricted Mode forwards all packets, unless specified otherwise through a bridge filter. If the Unrestricted Bridge Mode is selected, the following packet forward possibilities exist:

•If the packet matches a discard filter, it is discarded.

•If the packet matches a connect filter, it is connected and forwarded to the members of the dis- tribution list.

•If the packet matches no filter, the packet is forwarded. The specific forwarding action depends upon whether or not the destination is known. (See following descriptions.)

No Filter Match - Destination Known

If the destination is known and the corresponding device is on the Known Connect List, the connection is made and the packet is then forwarded to the specific destination.

If the device is not on the Known Connect list, the packet is sent to all current connections.

No Filter Match - Destination Unknown The packet is sent to all current connections.

RESTRICTED BRIDGE MODE

If the Restricted Bridge Mode is selected, packets will be discarded unless overridden by a user- defined bridge filter. The bridge filters, therefore, allow you to transfer only the packets that you specify.

If the Restricted Bridge Mode is selected, the following packet forwarding possibilities exist:

•If the packet matches a discard filter (packet filter only), it is discarded.

•If the packet matches a forward filter, it is forwarded to the distribution list.

•If the packet matches a connect filter, it is connected to the members of the distribution list. However, with Restricted Mode, the packet needs to match a forwarding filter in order to be forwarded.

•If the packet matches no filter, the specific action for the packet depends upon whether or not the destination is known. (See following descriptions.)

No Filter Match - Destination Known

If the destination is known and the corresponding device is on the Known Connect list, the con- nection is made. If the device is not on the Known Connect list, the packet is discarded.

No Filter Match - Destination Unknown The packet is discarded.

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