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350-501 · Question #282

Which action does the ingress VTEP perform on traffic between EVPN VXLAN overlays?

The correct answer is C. routing and bridging when doing asymmetric IRB. When an ingress VTEP handles traffic between different EVPN VXLAN overlays using asymmetric Integrated Routing and Bridging (IRB), it performs both bridging to receive the Layer 2 frame and routing to forward it to the correct destination Layer 2 VNI.

Networking

Question

Which action does the ingress VTEP perform on traffic between EVPN VXLAN overlays?

Options

  • Arouting and tunneling when doing symmetric IRB
  • Brouting when doing asymmetric IRB
  • Crouting and bridging when doing asymmetric IRB
  • Dbridging when doing symmetric IRB

How the community answered

(31 responses)
  • A
    10% (3)
  • B
    13% (4)
  • C
    74% (23)
  • D
    3% (1)

Why each option

When an ingress VTEP handles traffic between different EVPN VXLAN overlays using asymmetric Integrated Routing and Bridging (IRB), it performs both bridging to receive the Layer 2 frame and routing to forward it to the correct destination Layer 2 VNI.

Arouting and tunneling when doing symmetric IRB

While routing and tunneling are performed by the ingress VTEP in symmetric IRB, bridging is also implicitly involved to receive the initial Layer 2 frame, making 'routing and tunneling' an incomplete description of all ingress actions.

Brouting when doing asymmetric IRB

Simply stating 'routing' is incomplete because the ingress VTEP must also perform Layer 2 bridging to initially receive the packet from the host interface before routing.

Crouting and bridging when doing asymmetric IRBCorrect

With asymmetric IRB, the ingress VTEP is responsible for receiving the Layer 2 frame from the host (bridging function), performing the Layer 3 lookup and routing the packet from the source VNI to the destination VNI, and then encapsulating it into VXLAN. Therefore, it performs both routing and bridging actions for traffic moving between different EVPN VXLAN overlays.

Dbridging when doing symmetric IRB

Bridging is only one aspect; for traffic between overlays (i.e., different subnets), Layer 3 routing is also a necessary function performed by the VTEP, regardless of whether symmetric or asymmetric IRB is used.

Concept tested: EVPN VXLAN Ingress VTEP functions in Asymmetric IRB

Source: https://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/white-paper-c11-739912.html

Topics

#EVPN VXLAN#VTEP#Asymmetric IRB#Inter-subnet Routing

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