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VLAN-Based Service for EVPN

 

VLAN-based service allows a one-to-one mapping of a single broadcast domain to a single bridge domain. Each VLAN is mapped to a single EVPN instance (EVI), resulting in a separate bridge table for each VLAN. Prior to Junos OS Release 17.3R1, VLAN translation was not supported. Without VLAN translation, the customer edge VLAN must use the same VLAN ID (VID). You can still send an MPLS encapsulated frames with the originating VID. Figure 1 illustrates a topology where all the CE devices use the same CE VID for a single VLAN-based EVI. VID translation is not needed.

Figure 1: Single VID with no VLAN Translation
 Single VID with
no VLAN Translation

Starting with Junos OS Release 17.3R1, VLAN-based service with VID translation as described in RFC 7432 is supported. This means that Junos supports VID translation and the customer can have a different VID for each VLAN. As described in the RFC, the VID translation must be performed at the egress PE device while the MPLS encapsulated frames should also retain the originating VID. Figure 2 illustrates a topology where CE devices use different CE-VIDs for single VLAN-based EVI.

Figure 2: Multiple VIDs with VLAN Translation
Multiple VIDs with
VLAN Translation

For more information on configuring VLAN-based service, see Configuring EVPN with VLAN-Based Service.

The following is a sample configuration for a single VLAN-based EVI. The same VID is used on all the PE devices, so VLAN translation is not required. In this example, the VLAN-id=none statement is included to remove the originating VID and to set the Ethernet tag ID to zero in the MPLS frame.

The following is a sample configuration for a single VLAN-based EVI. The same VID is used on all the PE devices, so VLAN translation is not required. In this example, the CE-VID is used and sent as part of the MPLS frame.

Starting with Junos OS Release 17.3R1, Junos supports VLAN-based service with translation as described in RFC 7432. The following is a sample VLAN-based service configuration that adheres to a strict compliance of RFC 7432. Strict compliance to RFC 7432 requires that translation occurs at the egress PE device, the originating VID be carried in the MPLS frame, and the Ethernet tag ID be set to zero for all EVPN routes. Therefore, the VLAN-id=none and the no-normalization statements are included. This will set the Ethernet tag ID to zero, while ensuring that different VIDs can still be used.

The following is a sample VLAN-based service configuration that adheres to RFC 7432 except for the condition that the originating VID be carried in the Ethernet frame. The originating VID is removed and the Ethernet tag ID is set to zero.