Use this procedure to configure Ethernet ring protection (ERP).

The procedures in this section cover the following:

• Configuring a new ring.

• Adding a node to an existing ring.

• Deleting a node from an existing ring.

• Moving the ring protection link (RPL) or RPL owner.

Ethernet ring protection provides switching for Ethernet links connected in a ring configuration.

Figure 13-5, Ethernet ring protection shows a four-node ring. One of the links on Node 4 has been provisioned to be the Ring Protection Link (RPL). This is the link that by default is blocked for normal traffic. Node 4 is therefore the RPL Owner and blocks traffic bidirectionally. Switching is revertive – when a failure clears in the ring, the RPL is blocked (after a wait-to-restore delay).

The ring has a VLAN dedicated to APS signaling, called the R-APS channel. Messages are R-APS PDUs. When a change occurs in the ring, 3 R-APS PDUs are sent quickly; otherwise R-APS PDUs are sent every 5 seconds. Under most conditions, only a single node in the ring is sending R-APS messages. The link that is blocked in the ring is blocked bidirectionally by the RPL Owner, or by the node(s) detecting a failure. The R-APS channel within a blocked link is also partially blocked: it does not forward any messages it receives, but the node can initiate or receive messages.

Only optical SFP ports (d2-{1-4}) may be configured to be part of an ERP ring. Layer 2 control protocol tunneling must not be enabled on ports that are part of a protected Ethernet ring.

It is assumed the VLNC4x circuit packs have been installed and the physical optical links have been connected.

Important!

The example commands in these procedures use an arbitrary prompt (ALU Switching) in illustrating the commands. The actual default prompt, (ALU 1850TSS-5-xx), for the circuit pack you are logged into may appear, or the prompt you chose when setting up the system using the set prompt command.

Figure 13-5: Ethernet ring protection