ERP operational states

RPL nodes can be in one of six different states in Version 2:

When an ERP topology starts up, each ERN (in Init state) transmits a R-APS (NR). After start-up, the behavior varies by assigned role. The following table shows the initialization process for an ERN.

Message exchange and actions during ERN initialization version 2

Table 1. ERP operational states

RPL owner

Non-RPL node

RPL node

Init state

Init state

Init state
  1. Blocks the RPL.
  2. Sends a R-APS (NR).
  3. Enters the Pending state.
  1. Blocks the left interface.
  2. Sends a R-APS (NR).
  3. Enters the Pending state.
  1. Blocks the left interface.
  2. Sends a R-APS (NR).
  3. Enters the Pending state.

4. Starts the WTR timer.

5. (After the WTR expires) stops sending NR.

6. Sends R-APS (NR, RB, DNF).

7. Enters the Idle state.

After receiving the (NR, RB, DNF) from the RPL owner:

  1. Unblocks the non-failed blocking port.
  2. Stops sending (NR).
  3. Enters the Idle state.

After receiving the (NR, RB, DNF) from the RPL owner:

  1. Blocks the RPL port.
  2. Unblocks the other ports.
  3. Enters the Idle state.

When the ring is in the Pending state, an ERN flushes the filtering database (FDB) if it receives any of the following state requests:

Note

Note

ITU-T G.8032 Version 1 does not use a Pending state, so from the Protection state ERNs enter the Idle state.
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