C
HAPTER
14
| Basic Administration Protocols
Ethernet Ring Protection Switching
– 492 –
Figure 286:
Ring Interconnection Architecture
(Multi-ring/Ladder Network)
Configuration Guidelines for ERPS
1. Create an ERPS ring (Configure Domain – Add): The ring name is used
as an index in the G.8032 database.
2. Configure the east and west interfaces (Configure Domain – Configure
Details): Each node on the ring connects to it through two ring ports.
Configure one port connected to the next node in the ring to the east
(or clockwise direction) and another port facing west in the ring.
3. Configure the RPL owner (Configure Domain – Configure Details):
Configure one node in the ring as the Ring Protection Link (RPL) owner.
When this switch is configured as the RPL owner, the west ring port is
set as being connected to the RPL. Under normal operations (Idle
state), the RPL is blocked to ensure that a loop cannot form in the ring.
If a signal failure brings down any other link in the ring, the RPL will be
unblocked (Protection state) to ensure proper connectivity among all
ring nodes until the failure is recovered.
4. Configure ERPS timers (Configure Domain – Configure Details): Set the
Guard timer to prevent ring nodes from receiving outdated R-APS
messages, the Hold-off timer to filter out intermittent link faults, and
the WTR timer to verify that the ring has stabilized before blocking the
RPL after recovery from a signal failure.
5. Configure the ERPS Control VLAN (Configure Domain – Configure
Details): Specify the control VLAN (CVLAN) used to pass R-APS ring
maintenance commands. The CVLAN must NOT be configured with an
IP address. In addition, only ring ports may be added to the CVLAN
(prior to configuring the VLAN as a CVLAN). No other ports can be
members of this VLAN (once set as a CVLAN). Also, the ring ports of the
CVLAN must be tagged. Failure to observe these restrictions can result
in a loop in the network.
ring node Ar i ng nod e B
ring node C ring node D
r i ng nod e F ring node E
ERP1
ERP2
RPL
RPL
RPL Owner
Node
for ERP1
RPL Owner
Node
for ERP2
ring link
(ERP1)
ring node Aring node B
ring node C ring node D
ring node F ring node E
ERP1
ERP2
RPL
RPL
RPL Owner
Node
for ERP1
RPL Owner
Node
for ERP2
ring link
(ERP1)
FAILURE
Normal Condition Signal Fail Condition
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