4A0-115 Nokia Ethernet Virtual Private Network Services Questions and Answers

EVPN auto-discovery per Ethernet segment (A-D per ES) routes do not include an Ethernet tag ID that is set to zero. The Ethernet tag ID is set to a non-zero value that identifies the EVPN service instance1.

Verified References: Ethernet Virtual Private Networks (EVPNs)

When forwarding BUM traffic, the local PE does not replicate the traffic and send it as unicast to the advertising neighbor. Instead, the local PE uses an MPLS transport tunnel towards the advertising neighbor and sends the traffic with an MPLS label that indicates the service.

A non-designated forwarder (non-DF) in a single-active Ethernet segment blocks Tx unicast, allows Rx unicast, blocks Tx BUM, and allows Rx BUM. This prevents traffic duplication and ensures that only the DF forwards traffic to and from the CE.

PE3 does not set the P flag in its advertised A-D per EVI route to 1. PE3 sets the P flag to 0, indicating that it is not the DF for EVI 20. PE1 sets the P flag to 1, indicating that it is the DF for EVI 201.

Verified References: Ethernet Virtual Private Networks (EVPNs)

The EVPN Layer 2 Attributes extended community is not applicable to EVPN VPLS services. It is applicable to EVPN VPWS services, where it carries information such as the tag ID and the service MTU1.

Verified References: Ethernet Virtual Private Networks (EVPNs)

PE2 advertises a MAC/IP route for MAC1 with a sequence number higher than that received from PE1. This indicates that MAC1 has moved from PE1 to PE2 and triggers a MAC withdrawal message from PE1 to remote PEs. CE1 does not generate an update message to PE1 withdrawing its MAC, nor does PE1 generate an update message to remote PEs identifying the new location of CE11.

Verified References: Ethernet Virtual Private Networks (EVPNs)

PE1 sends the packet to PE2 and to PE3. An ESI label is included only in the packet sent to PE2. The ESI label is used to implement the split-horizon mechanism and prevent traffic duplication. The packet sent to PE3 does not need an ESI label because PE3 is connected to the same Ethernet segment as PE1.

A-D per EVI routes, A-D per ES routes, and Ethernet segment (ES) routes are exchanged to support the operation of a multi-homed EVPN VPWS. These routes are used to discover all PEs associated with an Ethernet segment, indicate the redundancy mode of the Ethernet segment, and elect the designated forwarder for each service.

PE3 does not add an ESI label to packets forwarded to PE1 because PE1 is connected to the same Ethernet segment. PE3 adds an ESI label only to packets forwarded to PEs that are not connected to the same Ethernet segment, such as PE21.

Verified References: Ethernet Virtual Private Networks (EVPNs)