Cabletron Systems ELS10-26 Guide de l'utilisateur télécharger pdf (Page 19)

Introduction

1-9

By forwarding only packets addressed to devices on other network

segments, the SmartSTACK 10 ELS10-26 reduces unnecessary

trafﬁc and thereby enhances the overall performance of the

network.

Note:

If the packet address is not found in the Bridge Address Table, it

will be forwarded (flooded) to all network segments.

Spanning Tree Algorithm

The SmartSTACK 10 ELS10-26 supports the IEEE 802.1d Spanning

Tree algorithm. The Spanning Tree algorithm converts multiple

LANs into a “spanning tree” of networks. It is used to prevent

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 SmartSTACK 10 ELS10-26, along with other IEEE 802.1d

Spanning Tree compliant bridges 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 (this is the

default setting).

When there are multiple SmartSTACK 10 ELS10-26s connecting

LANs in a loop, the Spanning Tree algorithm determines which

SmartSTACK 10 ELS10-26 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.

1.5.2 SmartSTACK 10 ELS10-26 Bridge Address Table

The SmartSTACK 10 ELS10-26 creates and maintains a dynamic

database of addresses called the Bridge Address Table. The

SmartSTACK 10 ELS10-26 examines every packet to determine its

source address and LAN segment origin. It then compares the

source address and segment information it ﬁnds to the entries in

the Bridge Address Table.

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Cabletron Systems ELS10-26 Guide de l'utilisateur Page 19