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QSW-3900-48-SFP-DC
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Qtech QSW-3900-48-SFP-DC [228/245] Errp ring

QTECH Software Configuration Manual

20-227

20.3.2 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.

20.3.3 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.

20.3.4 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.

20.3.5 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.

1) In terms of functionality, the difference between the primary port and the secondary port of a master node is :

· The primary port and the secondary port are designed to play the role of sending and receiving loop-detect

packets respectively.

· When an ERRP ring is in health state, the secondary port of the master node will logically deny data VLANs

and permit only the packets of the control VLANs.

· When an ERRP ring is in disconnect state, the secondary port of the master node will permit data VLANs,

that is, forward packets of data VLANs.

2) In terms of functionality, there is no difference between the primary port and the secondary port of the transit

node. Both are designed for the transfer of protocol packets and data packets over an ERRP ring.

As shown in Figure 1, Device A is the master node of Ring 1. Port 1 and port 2 are the primary port and the

secondary port of the master node on Ring 1 respectively. Device B, Device C and Device D are the transit nodes of

Ring 1. Their port 1 and port 2 are the primary port and the secondary port on Ring 1 respectively.

Qtech QSW-3900-48-SFP-DC [228/245] Errp ring

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