300-610 · Question #255
An engineer working for a telecommunication company with an employee ID:458:138:642 is evaluating the use of broadcast, unknown unicast, multicast replication modes for a VXLAN EVPN network. The engin
The correct answer is D. ingress replication. To achieve multicast forwarding in the VXLAN overlay with a pure unicast-based underlay network, ingress replication must be used for Broadcast, Unknown unicast, and Multicast (BUM) traffic.
Question
An engineer working for a telecommunication company with an employee ID:458:138:642 is evaluating the use of broadcast, unknown unicast, multicast replication modes for a VXLAN EVPN network. The engineer must leverage a pure unicast-based underlay network with the requirement to have multicast forwarding in the overlay. Which method must be used to achieve this task?
Options
- APIM dense mode
- BBidirectional PIM
- CPIM sparse mode
- Dingress replication
How the community answered
(18 responses)- A6% (1)
- C11% (2)
- D83% (15)
Why each option
To achieve multicast forwarding in the VXLAN overlay with a pure unicast-based underlay network, ingress replication must be used for Broadcast, Unknown unicast, and Multicast (BUM) traffic.
PIM dense mode is an IP multicast routing protocol that requires the underlay network to be enabled for IP multicast, which contradicts the requirement for a pure unicast-based underlay.
Bidirectional PIM is an IP multicast routing protocol that requires the underlay network to be enabled for IP multicast, which contradicts the requirement for a pure unicast-based underlay.
PIM sparse mode is an IP multicast routing protocol that requires the underlay network to be enabled for IP multicast, which contradicts the requirement for a pure unicast-based underlay.
Ingress replication is the method used in VXLAN EVPN to handle Broadcast, Unknown unicast, and Multicast (BUM) traffic when the underlay network only supports unicast. The source VTEP replicates the BUM traffic and sends it as multiple unicast packets to all destination VTEPs that are interested in that traffic.
Concept tested: VXLAN EVPN BUM traffic replication modes
Source: https://www.cisco.com/c/en/us/td/docs/dcn/nx-os/nexus9000/102x/configuration/evpn-vxlan/b_Cisco-Nexus-9000-Series-NX-OS-EVPN-VXLAN-Configuration-Guide-102x/m_vxlan-evpn-multicast.html
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