PLANET WGSW-52040 - Manual (Page 442)

55-13
Break state: one or a few physical link break in ring network
3. nodes
Each switch is named after a node on Ethernet. The node has some types:
Primary node: each ring has a primary node, it is main node to detect and defend.
Transfer node: except for primary node, other nodes are transfer nodes on each ring.
The node role is determined by user configuration. As shown Figure 55-1, Switch A is primary node of Ring 1,
Switch B. Switch C; Switch D and Switch E are transfer nodes of Ring 1.
4. Primary port and secondary port
The primary node and transfer node have two ports connecting to Ethernet separately, one is primary port,
and another is secondary port. The role of port is determined by user configuration.
Primary port and secondary port of primary node.
The primary port of primary node is used to send ring health examine packet (hello), the secondary port is
used to receive Hello packet sending from primary node. When the Ethernet is in health state, the secondary
port of primary node blocks other data in logical and only MRPP packet can pass. When the Ethernet is in
break state, the secondary port of primary node releases block state, and forwards data packets.
There are no difference on function between Primary port and secondary port of transfer node.
The role of port is determined by user configuration. As shown Figure 55-1, Switch A E1 is primary port, E2 is
secondary port.
5. Timer
The two timers are used when the primary node sends and receives MRPP protocol packet: Hello timer and
Fail Timer.
Hello timer: define timer of time interval of health examine packet sending by primary node primary port.
Fail timer: define timer of overtime interval of health examine packet receiving by primary node primary port.
The value of Fail timer must be more than or equal to the 3 times of value of Hello timer.
55.1.2 MRPP Protocol Packet Types
Packet Type Explanation
Hello packet (Health examine packet) Hello The primary port of primary node evokes to detect ring, if the
secondary port of primary node can receive Hello packet in
configured overtime, so the ring is normal.
LINK-DOWN (link Down event packet) After transfer node detects Down event on port, immediately
sends LINK-DOWN packet to primary node, and inform primary
node ring to fail.