Juniper ACX1000 Configuration Manual page 190

ACX Series Universal Access Router Configuration Guide
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to be not used for Ethernet ring protection. You can configure a ring port over LAG
interfaces.
NOTE: ERPS on aggregated Ethernet interface is supported on ACX5000
line of routers.
ITU G.8031 Ethernet automatic protection switching (APS) and ERPS version 2 are not
supported. Also, you cannot configure ACX Series routers as trunk ports or access ports
in an Ethernet ring.
Multiple Ethernet ring instances that share the same physical ring are supported. Each
ring instance will have its own control channel and a specific data channel. You can
configure the data channel with a set of data VLAN IDs that belong to a ring instance.
Each ring instance can follow a different path to perform load balancing in the physical
ring. If you do not specify a data channel, ERPS operates on the VLAN ID associated with
the control channel. There is no limit to the number of VLAN IDs that you can configure
for a data channel.
Keep the following points in mind when you configure ERPS for ACX Series routers:
The logical interfaces that you define for a control channel must be part of the same
bridge domain.
Each VLAN that you configure in a data channel signifies an independent bridge domain.
The traffic that is blocked on a ring port is the same for all the bridge domains that are
associated with the same control channel. When a topology change happens, the
forwarding databases of all these bridge domains are cleared.
You cannot configure spanning-tree protocol (STP) (such as MSTP, RSTP, VSTP and
STP) and ERP on the same set of interfaces. However, ERP and Per-VLAN Spanning
Tree (PVST) can be configured on the same topology as long as PVST does not share
the same VLAN with any Ethernet ring instance configured on the physical port.
You cannot configure STP and ERPS in the same bridge domain. Consider a sample
scenario in which a dual-homed customer edge (CE) router is connected to two ACX
Series routers, which function as provider edge (PE) devices. In such a topology, you
can configure either STP or an ERPS open ring to enable dual-homing functionality.
You can configure STP between the CE and the user-to-network interface (UNI) ports
of the two PE devices. Alternatively, if the CE router supports ERPS, you can configure
an open ring in the CE network.
In the event of a single failure, switching times on all ACX routers is less than 100
milliseconds.
The following parameters can impact the performance of the system based on your
network configuration:
Number of protocols (Layer 2, Layer 3, or MPLS) affected by a certain network failure
Number of ring instances corresponding to the ring that is impacted by the failure
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