Ethernet G.8032 rings
Overview
Ethernet Ring Protection (ERP) as specified in ITU-T G.8032, is a protection mechanism for Ethernet ring topologies that provides a resilient Ethernet network. ERP provides sub-50ms protection and recovery switching for Ethernet traffic in a ring topology, and, at the same time, ensures that loops are not formed at the Ethernet layer. G.8032v1 supports a single ring topology; G.8032v2 supports multiple rings/ladder topology. For more information about Ethernet G.8032 rings, see the ITU website at http://itu.int.
ERP topology
An ERP topology is a collection of Ethernet ring nodes that forms a closed physical loop. Between two and sixteen Ethernet ring nodes are supported per ERP topology. One ERP topology is supported per NE. Up to two ERP instances are supported per ERP topology. Ethernet ring links connect two adjacent Ethernet ring nodes participating in the same ERP topology.
Loop avoidance in the ring is achieved by guaranteeing that at anytime, traffic may flow on all but one of the ring links. This link is called the ring protection link (RPL). One designated node, the RPL Owner (also referred to as the master node), is responsible to block traffic over the RPL.
Supported ERP service types
You can configure the following service types in an ERP G.8032 topology using the NFM-P on NEs that support ERP:
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VPLS that support ERP SAPs can connect to other rings and Ethernet services using VPLS SAPs. A VPLS can use a single ring (main or sub-ring) or multiple rings.
Ethernet ring discovery
The NFM-P automatically unites discovered Ethernet ring elements in the network into Ethernet rings, and creates path objects to link endpoints within the ring. In order for the NFM-P to create an Ethernet ring, the following must exist:
The NFM-P detects the ring elements and the physical link, then creates an Ethernet ring to contain the ring elements, and path objects to link them. If one of the ring elements is already part of an Ethernet ring, then the other element is added to the existing ring. If both elements are part of existing rings, then the rings are merged (see Merging Ethernet rings below).
See Workflow to configure Ethernet G.8032 rings for information about using the NFM-P to automatically create Ethernet rings.
You can manually create Ethernet G.8032 rings using the NFM-P GUI or using the OSS service provisioning client. See To create an Ethernet G.8032 ring to create Ethernet G.8032 rings using the NFM-P GUI. See “MPLS, LSP, and service tunnel configuration” in the NSP NFM-P XML API Developer Guide for information about configuring Ethernet G.8032 rings using the OSS client application.
Triggering automatic ring creation
Automatic Ethernet ring creation is triggered by the following events:
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creation or detection of a path endpoint on an Ethernet ring element
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creation or detection of a physical link between two path endpoints on Ethernet ring objects
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performance of a global Ethernet ring audit (see Auditing Ethernet rings )
Path endpoints and physical links can be detected through LLDP or when a node is discovered, or created through NFM-P or CLI. In each case, the NFM-P attempts to create an appropriate Ethernet ring for the discovered object.
Ethernet sub-rings
The NFM-P also detects and creates Ethernet sub-rings, and creates interconnects between upper rings and sub-rings when appropriate. You can view the sub-rings associated with a ring in the Sub-Rings tab of the Ethernet ring configuration form, and the parent upper rings on the Upper Rings tab.
Merging Ethernet rings
When the NFM-P detects a physical link between two Ethernet ring element path endpoints on separate Ethernet rings, the rings are automatically merged together. One of the Ethernet rings is deleted, and the elements and paths from that ring are added to the other ring. The following criteria are used to determine which ring is deleted:
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If one of the rings was created manually using the NFM-P, then the other ring is merged into the manually-created ring.
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If both rings were created manually, then the smaller ring is merged into the larger ring, based on the number of Ethernet ring elements.
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If both rings were created automatically, then the smaller ring is merged into the larger ring, based on the number of Ethernet ring elements.
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If the rings have the same number of elements, and were both created the in the same manner, then the ring with the higher Manager ID is merged into the other ring.
Naming of discovered Ethernet rings
Global Ethernet rings inherit the Description parameter of the first element added to the ring. The Name parameter for automatically created rings is always “N/A”.
Deleting Ethernet rings
Automatically created Ethernet rings are deleted when the underlying physical links are removed. When a physical link is deleted - for example, manually, or by disabling LLDP on the related node - the associated path is also deleted, and the existing Ethernet ring is modified or deleted appropriately.
Adding or removing elements in an Ethernet ring
You can cut-in or cut-out an NE in an existing Ethernet ring as part of a network adjustment. The NFM-P alters the existing Ethernet rings and updates the associated endpoints and services to reflect the new configuration.
To add (cut-in) an NE to an Ethernet ring, perform the following:
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Shut down ports on NEs that will be connected to the cut-in NE.
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Configure Ethernet ring endpoints on the cut-in NE. See To create a physical link.
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Update OAM parameters for NEs to be connected to the cut-in NE. See Chapter 77, VPLS management.
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Re-cable the network to include the cut-in NE in the Ethernet ring.
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(In-band network only) Configure the cut-in NE as an Ethernet ring element (including control SAPs). See To configure an Ethernet Ring Element.
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Discover the cut-in node in the NFM-P. See Discovering devices using the NFM-P.
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The NFM-P creates paths and merges them appropriately into the Ethernet rings. (Out-of-band network only) Control SAPs for the cut-in NE are created on the associated control VPLS automatically.
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You can perform an Ethernet ring audit to verify that the rings have been created properly. See To perform an Ethernet G.8032 ring audit.
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Trigger an Update Data Service function to create data SAPs on the cut-in NE and to the associated data VPLS. See To manually update data services on an Ethernet ring.
To remove (cut-out) an NE from an Ethernet ring, perform the following:
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Update OAM parameters for NEs connected to the cut-out NE. See Chapter 77, VPLS management.
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Re-cable the network to exclude the cut-out NE from the Ethernet ring.
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Unmanage the cut-out NE in the NFM-P. See To manage, suspend, or unmanage a device.
Auditing Ethernet rings
You can use the NFM-P to perform a global or local audit of an Ethernet ring. An audit can find missing elements, paths, and interconnects, and potentially merge rings if a link is found. When an audit discovers a problem that cannot be resolved, an alarm is raised against the Ethernet ring, and the problems encountered by the audit are displayed in the alarm details. Performing another audit clears the alarm, if the problems have been resolved.
To perform an Ethernet G.8032 ring audit describes how to audit Ethernet rings. Performing a global Ethernet ring audit both creates and merges Ethernet rings, even if automatic Ethernet ring creation is disabled.
Service provisioning on Ethernet G.8032 rings
The NFM-P accelerates the provisioning of VPLS instances on Ethernet G.8032 rings by automatically creating the control services and data services on the rings. Services are configured on Ethernet G.8032 rings in the same method as service tunnels.
You can automatically configure transit services on VPLS G.8032 Ethernet rings. See Transit services in Ethernet G.8031 tunnels and To configure a transit service on an Ethernet ring for more information.
You can create Ethernet G.8032 rings using the NFM-P GUI or using the OSS service provisioning client. See To create an Ethernet G.8032 ring to create Ethernet G.8032 rings using the NFM-P GUI. See “MPLS, LSP, and service tunnel configuration” in the NSP NFM-P XML API Developer Guide for information about configuring Ethernet G.8032 rings using the OSS client application.