Manual

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Москва, Новозаводская ул., 18, стр. 1
308
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 Fig 3-1, 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, 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.
33.1.2 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.