Ethernet Local Management Interface

Gigabit Ethernet (ge), 10-Gigabit Ethernet (xe), and 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) 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. 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 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

The E-LMI implementation on ACX and MX 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 (SVLAN domain or VPLS).

The E-LMI protocol relays the following information:

• Notification to the CE of the addition/deletion of an EVC (active, not active, or partially active)

• Notification to the CE of the availability state of a configured EVC

• Communication of UNI and EVC attributes to the CE:

  • UNI attributes:

    • UNI identifier (a user-configured name for UNI)

    • CE-VLAN ID/EVC map type (all-to-one bundling, service multiplexing with bundling, or no bundling)

    • Bandwidth profile is not supported (including the following features):

      • CM (coupling mode)

      • CF (color flag)

      • CIR (committed Information rate)

      • CBR (committed burst size)

      • EIR (excess information rate)

      • EBS (excess burst size)

  • EVC attributes:

    • EVC reference ID

    • EVC status type (active, not active, or partially active)

    • EVC type (point-to-point or multipoint-to-multipoint)

    • EVC ID (a user-configured name for EVC)

    • Bandwidth profile (not supported)

  • CE-VLAN ID/EVC map

E-LMI on MX Series routers supports the following EVC types:

• Q-in-Q SVLAN (point-to-point or multipoint-to-multipoint)—Requires an end-to-end CFM session between UNI-Ns to monitor the EVS status.

• VPLS (BGP or LDP) (point-to-point or multipoint-to-multipoint)—Either VPLS pseudowire status or end-to-end CFM sessions between UNI-Ns can be used to monitor EVC status.

• L2 circuit/L2VPN (point-to-point)—Either VPLS pseudowire status or end-to-end CFM sessions between UNI-Ns can be used to monitor EVC status.

  Note:

  l2-circuit and l2vpn are not supported.

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.

To configure E-LMI, perform the following steps:

• Configuring an OAM Protocol (CFM)
• Assigning the OAM Protocol to an EVC
• Enabling E-LMI on an Interface and Mapping CE VLAN IDs to an EVC

• Example Topology
• Configuring PE1
• Configuring PE2
• Configuring Two UNIs Sharing the Same EVC

Example Topology

Figure 2 illustrates the E-LMI configuration for a point-to-point EVC (SVLAN) monitored by CFM. In this example, VLANs 1 through 2048 are mapped to evc1 (SVLAN 100) and 2049 through 4096 are mapped to evc2 (SVLAN 200). Two CFM sessions are created to monitor these EVCs.

Figure 2: E-LMI Configuration for a Point-to-Point EVC (SVLAN) Monitored by CFM