Understanding VLAN-Aware Bundle and VLAN-Based Service for EVPN
A Data Center Service Provider (DCSP) hosts the data center for its multiple customers on a common physical network. To each customer (also called a tenant), the service looks like a full-fledged data center that can expand to 4094 VLANs and all private subnets. For disaster recovery, high availability, and optimization of resource utilization, it is common for the DCSP to span across the data center to more than one site. When deploying the data center services, a DCSP faces the following main challenges:
Extending Layer 2 domains across more than one data center site. This requires optimal intra-subnet traffic forwarding.
Supporting optimal inter-subnet traffic forwarding and optimal routing in the event of virtual machine (VM).
Supporting multiple tenants with independent VLAN and subnet space.
The DCSP might require Ethernet VLAN services to be extended over a WAN with a single EVPN instance (EVI). On the QFX Series, each EVPN and virtual switch routing instance corresponds to an EVI. The QFX Series supports VLAN-aware bundle service and VLAN-based service, which maintain data and control plane separation.
If you create VLANs that are not part of a routing instance, they become part of the Default Switch routing instance.
VLAN-Aware Bundle Service
VLAN-aware bundle services supports the mapping of one or more routing instances of type Virtual Switch to many VLAN IDs (VIDs) and multiple bridge tables, with each bridge table corresponding to a different VLAN. To enable VLAN-aware bundle service, configure a Virtual Switch routing instance. For service provider-related applications, where the VLAN ID is local to the Layer 2 logic interface, enable the flexible-vlan-tagging statement in your configuration. For enterprise-related applications, where the VLAN ID has global significance, enable the family ethernet-switching statement in your configuration. VLAN-aware bundle service supports up to 4000 VLANs per routing instance.
VLAN-based service supports the mapping of one routing instance of type EVPN to one VLAN. There is only one bridge table that corresponds to the one VLAN. If the VLAN consists of multiple VLAN IDs (VIDs)—for example, there is a different VID per Ethernet segment on a provider edge device—then VLAN translation is required for packets that are destined to the Ethernet segment. To enable VLAN-based service, configure an EVPN routing instance. Up to 100 EVPN routing instances are supported.