Enterasys fn100 Betriebsanweisung

 

Introduction

 

The FN100 supports the IEEE 802.1d Spanning Tree algorithm. The 
Spanning Tree algorithm converts multiple LANs into a “spanning tree” 
of networks that prevents bridging loops. This standard defines a logical 
(not physical) network configuration consisting of one extended LAN 
without active duplicate paths between spanning tree bridges.

The FN100, along with other IEEE 802.1d Spanning Tree compliant 
bridges or switches in the network, dynamically configure the network 
topology into a single Spanning Tree by exchanging Bridge Protocol Data 
Units (BPDUs). Typically, each LAN segment is sent one BPDU every 
two seconds.

When there are multiple FN100 switches connecting LANs in a loop, the 
Spanning Tree algorithm determines which FN100 should forward 
packets to the LAN. If there is a cable break or a port failure, the network 
topology is automatically reconfigured by the Spanning Tree protocol to 
create an alternate path to the LAN.

 

The FN100 creates and maintains a dynamic database of addresses called 
the Bridge Address Table. The FN100 examines every packet to 
determine its source address and LAN segment origin. It then compares 
the source address and segment information to the entries in the Bridge 
Address Table.

If a packet’s address is not already stored in the Bridge Address Table, the 
FN100 adds general information including learned address, associated 
segment number, trunk group information, and virtual switch information. 
Consequently, the FN100 knows the address and associated segment 
number the next time it sees that address. By using the information stored 
in the Bridge Address Table, the FN100 is able to quickly forward each 
packet to the correct LAN segment.