Qtech QSW-2900-24T4-AC [189/209] Errp ring

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As shown in Figure 1, Domain 1 is an ERRP domain, including two ERRP rings: Ring 1 and Ring 2. All the

nodes on the two ERRP rings belong to the ERRP domain.

16.3.2 ERRP ring

A ring-shaped Ethernet topology is called an ERRP ring. An ERRP domain is built up on an ERRP ring. An

ERRP ring falls into primary ring and subring. Both levels are set to 0 and 1 respectively when configuration.

As shown in Figure 1, Domain 1 contains two ERRP rings: Ring 1 and Ring 2. Ring 1 level is set to 0,

meaning the primary ring; Ring 2 level is set to 1, meaning the subring.

For a ring, there are two cases:

· Health state: All the physical links on the Ethernet ring are connected.

· Disconnect state: Some physical link on the Ethernet ring fails.

16.3.3 Control VLAN and data VLAN

· Control VLAN is a VLAN specially designed to transfer ERRP packets. The ports accessing an ERRP ring

on devices belong to the control VLAN of the ring and only these ports can join this VLAN. IP address

configuration is prohibited on the ports of the control VLAN. You can configure a control VLAN for the

primary ring (namely the primary control VLAN). However, the control VLAN of a subring (namely the

secondary control VLAN) is assigned automatically by the system and its VLAN ID is the control VLAN ID

of the primary ring plus 1.

· Data VLAN is a VLAN designed to transfer data packets, including the ports accessing the Ethernet ring and

other ports on devices.

16.3.4 Node

Every device on an ERRP ring is referred to as a node. Node mode includes:

· Master node: Each ring has a master node primarily used to make loop detection and loop guard.

· Transit node: All the nodes excluding the master node on the primary ring; and all the nodes on a subring

except for the master node and the nodes where the primary ring intersects with the subring.

· Edge node: A node residing on the primary ring and a subring at the same time. The node is a special transit

node that serves as a transit node on the primary ring and an edge node on the subring.

· Assistant-edge node: A node residing on the primary ring and a subring at the same time. The node is a

special transit node that serves as a transit node on the primary ring and an assistant-edge node on the

subring. This node is used in conjunction with the edge node to detect the integrity of the primary ring and

perform loop guard.

As shown in Figure 1, Ring 1 is the primary ring and Ring 2 is a subring. Device A is the master node of Ring

1, Device B, Device C and Device D are the transit nodes of Ring 1; Device B and Device C reside on Ring 2 at

the same time, so they are the edge nodes of Ring 2. You can specify one of them as an edge node and the other as an

assistant edge node. Device E is the master node of Ring 2.

16.3.5 Primary port and secondary port

Each master node or transit node has two ports accessing an ERRP ring, in which one serves as the primary

port and the other serves as the secondary port. You can determine the role of a port.