Siemens OSM Bedienungsanleitung PDF herunterladen (Seite 26)

Important OSM/ESM Functions

2-6

Industrial Ethernet OSM/ESM Network Management

C79000-G8976-C137-08

2.5.2 Displaying and Deleting FDB Entries, Aging

The entries in the FDB table can be displayed by the WBM, see Section 4.10.1.

Static addresses can also be entered or deleted in WBM.

If aging is activated (default), a learned entry (address) is automatically deleted

in the FDB table when no packet with this source address is received within the

aging time.

Aging prevents addresses that are no longer up to date from remaining in the FDB

table permanently. “Aged entries” can, for example, mean that a node that has

been connected to a different OSM/ESM port is no longer obtainable because the

packets intended for it are still sent to the original port.

In WBM and in the CLI, aging can be enabled and disabled and the aging time can

be modified. The default setting for the aging time is 40 seconds.

2.5.3 Reaction to Spanning Tree Frames

When an OSM/ESM is interfaced to a higher-level office network, users often

require this interface to be implemented redundantly. The company network,

however, uses third-party components that do not support fast OSM/ESM

redundancy mechanisms (forming rings and standby links). At other points in the

office network, a mesh topology is used and the resulting loops are eliminated by

the spanning tree protocol (IEEE 802.1D).

As of firmware version 2.3.5, OSMs/ESMs are capable of evaluating spanning tree

frames that report modified configurations in the office network. This allows an

OSM/ESM ring to interface redundantly with an office network based on spanning

tree.

During configuration changes (triggered by topology change events) made in a

connected spanning tree office network, an OSM/ESM reduces its aging time. As a

result, the MAC addresses of all stations (for example PCs) from which no further

frames are received during this shortened time are removed from the address

table. Stations that use new or modified network paths following a change in the

configuration can therefore be reached again more quickly. On completion of the

configuration changes, the OSM/ESM changes back to normal operation.

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Siemens OSM Bedienungsanleitung Seite 26