Configuring the ECN330-switch
258 1553-KDU 137 365 Uen D 2006-06-16
CLI – This example sets the MSTP attributes for port 4.
6.11 Ethernet Automatic Protection Switching Configuration
Note: The information provided in this section is based on RFC 3619.
Ethernet Automatic Protection Switching
™ (EAPS) can be used to increase the
availability and robustness of Ethernet rings. An Ethernet ring built using EAPS
can have resilience comparable to that provided by SONET BSHR or SDH MS-
SPRing configurations, at a lower cost and with fewer constraints (for example,
ring size).
Many Metropolitan Area Networks (MANs) use a ring topology. EAPS works well
in ring topologies for either MANs or LANs. MAN operators want to minimize the
recovery time in the event of a fibre cut. EAPS technology converges in less than
one second, often in less than 500 milliseconds. Also, EAPS does not limit the
number of nodes in the ring, and the convergence time is independent of the
number of nodes in the ring.
Operational Concept – An EAPS Domain exists on a single Ethernet ring. Any
VLAN that is to be protected is configured on all ports in the ring for the given
EAPS Domain. Each EAPS Domain has a single designated "master node." All
other nodes on that ring are referred to as "transit nodes."
Each node has two ports connected to the ring. One port of the master node is
designated as the "primary port" to the ring, carrying control messages and
data, while the other port is designated as the "secondary port" and runs in
backup mode.
In normal operation, the master node blocks the secondary port for all non-
control Ethernet frames belonging to the given EAPS Domain, thereby avoiding
a loop in the ring. Existing Ethernet switching and learning mechanisms operate
per existing standards on this ring. This is possible because the master node
makes the ring appear as though there is no loop from the perspective of the
Ethernet standard algorithms used for switching and learning. If the master
node detects a ring fault, it unblocks its secondary port and allows Ethernet data
Console(config)#interface ethernet 1/4
Console(config-if)#spanning-tree mst port-priority 0
Console(config-if)#spanning-tree mst cost 50
Console(config-if)
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