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    Configuring Ethernet Local Management Interface on ACX Series

    Ethernet Local Management Interface Overview

    ACX Series routers with Gigabit Ethernet (ge), 10-Gigabit Ethernet (xe), or Aggregated Ethernet (ae) interfaces support the Ethernet Local Management Interface (E-LMI). The E-LMI specification is available at the Metro Ethernet Forum. E-LMI procedures and protocols are used for enabling automatic configuration of the customer edge (CE) device to support Metro Ethernet services. The E-LMI protocol also provides user-to-network interface (UNI) and Ethernet virtual connection (EVC) status information to the CE device. The UNI and EVC information enables automatic configuration of CE operation based on the Metro Ethernet configuration.

    The E-LMI protocol operates between the CE device and the provider edge (PE) device. It runs only on the PE-CE link and notifies the CE device of connectivity status and configuration parameters of Ethernet services available on the CE port. The scope of the E-LMI protocol is shown in Figure 1.

    Figure 1: Scope of the E-LMI Protocol

    Scope of the E-LMI Protocol

    The E-LMI implementation on ACX Series routers includes only the PE side of the E-LMI protocol.

    E-LMI interoperates with an OAM protocol, such as connectivity fault management (CFM), that runs within the provider network to collect OAM status. CFM runs at the provider maintenance level (UNI-N to UNI-N with up MEPs at the UNI). E-LMI relies on the CFM for end-to-end status of EVCs across CFM domains.

    The E-LMI protocol relays the following information:

    • Notification to the CE device of the addition or deletion of an EVC (active, not active)
    • Notification to the CE device of the availability state of a configured EVC
    • Communication of UNI and EVC attributes to the CE device:
      • UNI attributes:
        • UNI identifier (a user-configured name for UNI)
        • CE-VLAN ID and EVC map type (all-to-one bundling, service multiplexing with bundling, or no bundling)
      • EVC attributes:
        • EVC reference ID
        • EVC status type (active, not active)
        • EVC type (point-to-point)
        • EVC ID (a user-configured name for EVC)
      • CE-VLAN ID and EVC map

    The E-LMI protocol on ACX Series routers supports Layer 2 circuit and Layer 2 VPN EVC types and enables link-loss forwarding for pseudowire (Layer 2 circuit and Layer 2 VPN) services as follows:

    • Interworking between the connectivity fault management (CFM) protocol and the E-LMI protocol for Layer 2 circuit and Layer 2 VPN.
      • End-to-end CFM session between UNIs to monitor EVC status.
      • In the case of pseudowire redundancy, CFM can be used to monitor active and backup pseudowire sessions. The EVC status is declared as down to CE devices only when both the active and backup pseudowire sessions go down.
    • Interworking between remote defect indication (RDI) and E-LMI for Layer 2 circuit and Layer 2 VPN.
      • If a maintenance association end point (MEP) receives an RDI bit set in a continuity check message (CCM) frame, and if RDI fault detection is enabled in the EVC configuration at [edit protocols oam ethernet evcs evc-id evc-protocol cfm management-domain name management-association name faults rdi], then the pseudowire is declared as down to CE routers through E-LMI.
    • If an end-to-end CFM session does not exist between UNIs, the pseudowire (Layer 2 circuit or Layer 2 VPN) up and down state triggers an asynchronous EVC state change message to CE routers through E-LMI.

    Note: ACX Series routers do not support E-LMI for Layer 2 services (bridging).

    Configuring the Ethernet Local Management Interface

    To configure E-LMI, perform the following steps:

    Configuring an OAM Protocol (CFM)

    For information about configuring the OAM protocol (CFM), see IEEE 802.1ag OAM Connectivity Fault Management Overview.

    Assigning the OAM Protocol to an EVC

    To assign an OAM protocol to an EVC, you must specify a name for the EVC by using the evcs evc-id statement at the [edit protocols oam ethernet] hierarchy level. You can set the evc-protocol statement to cfm, l2circuit, or l2vpn to monitor the EVC status and its options at the [edit protocols oam ethernet evcs] hierarchy level. You can configure the number of remote UNIs in the EVC by using the remote-uni-count number statement. The remote-uni-count value defaults to 1.

    You can configure an EVC by including the evcs statement at the [edit protocols oam ethernet] hierarchy level:

    [edit protocols oam ethernet]
    evcs evc-id {
    evc-protocol (cfm management-domain name management-association name faults rdi; | l2circuit interface interface-name | l2vpn interface interface-name;)
    remote-uni-count count; # Optional, defaults to 1
    async-status-msg-transmit-interval interval (1ms|1000ms) ; # Defaults to 10ms.
    }

    Enabling E-LMI on an Interface and Mapping CE VLAN IDs to an EVC

    To configure E-LMI, include the lmi statement at the [edit protocols oam ethernet] hierarchy level:

    [edit protocols oam ethernet]
    lmi {
    polling-verification-timer value;
    # Polling verification timer (T392), defaults to 15 seconds
    status-counter count; # Status counter (N393), defaults to 4
    interface name {
    evc evc-id {
    default-evc;
    vlan-list [ vlan-ids ];
    }
    evc-map-type (all-to-one-bundling | bundling | service-multiplexing);
    polling-verification-time value; # Optional, defaults to global value
    status-counter count; # Optional, defaults to global value
    uni-id value; # Optional, defaults to interface-name
    }
    }

    You can set the status counter to count consecutive errors by using the status-counter count statement at the [edit protocols oam ethernet lmi] hierarchy level. The status counter is used to determine whether E-LMI is operational or not. The default value is 4.

    You can set the polling-verification-timer value statement at the [edit protocols oam ethernet lmi] hierarchy level. The default value is 15 seconds.

    You can enable an interface and set its options for use with E-LMI by using the interface name statement at the [edit protocols oam ethernet lmi] hierarchy level. Only ge, xe, and ae interfaces are supported. You can use the interface uni-id option to specify a name for the UNI. If uni-id is not configured, it defaults to the name variable in the interface name statement.

    You can specify the CE-VLAN ID and EVC map type by using the evc-map-type type interface option. The options are all-to-one-bundling, bundling, and service-multiplexing. Service multiplexing is with no bundling. The default type is all-to-one-bundling.

    To specify the EVC that an interface uses, use the evc evc-id statement at the [edit protocols oam ethernet lmi interface name] hierarchy level. You can specify an interface as the default EVC interface by using the default-evc statement at the [edit protocols oam ethernet lmi interface name evc evc-id] hierarchy level. All VLAN IDs that are not mapped to any other EVCs are mapped to this EVC. Only one EVC can be configured as the default.

    You can map a list of VLANs to an EVC by using the vlan-list vlan-id-list statement at the [edit protocols oam ethernet lmi interface name evc evc-id] hierarchy level.

     

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    Modified: 2017-09-13