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Specifications

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CLI Management Guide
TigerAccess™ EE
290 SMC7824M/VSW
ERP Messages
There are five types of ERP messages of concern to the RM node-Normal node interac-
tion in ERP ring as shown below:
• Normal Node messages
The following messages are sent by the normal nodes to inform RM node of their link
changes.
– Link Down: A normal node sends Link Down messages detecting its link failure.
– Link Up: A normal node sends Link Up messages detecting its link recovery.
• RM Node messages
A RM node is in charge of protecting the Ethernet ring. It sends periodic Test Packet
messages to normal nodes and receives Link Down/Up message from those nodes
to detect the link failure or recovery.
– Test Packet (TP): This is used to determine if any loops occur in the Ethernet ring.
– RM Link Down: This is used to inform the normal nodes of unblocking status of its
secondary port caused by link failure.
– RM Link Up: This is used to inform the normal nodes of re-blocking status of its
secondary port caused by link recovery.
ERP implementation of the switch has the following restrictions, so you should keep in
mind those before configuring ERP.
• ERP can not be configured with STP. If ERP is enabled in the system, STP is
automatically disabled.
• A primary and secondary port number should not be same.
• ERP mechanism should be used for Ethernet Ring topology only.
If the link failure occurs, the nodes adjacent (Node A & B) to the failure detect their state
and send Link Down message to RM node. If an intermediate node (Node C) between
RM node and a node adjacent to link failure receives Link Down message, it starts to per-
form Forwarding Database (FDB) Flushing. FDB Flushing consists in erasing in the for-
warding database of the switch all MAC entries of the protected VLANs that are for-
warded to the ring ports. The Flushing of FDB is always followed by a period with learning
disabled. To prevent wrong MAC learning due to the remaining packets in the buffer, a
node does not learn MAC addresses during a configured learning disable time.
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