Explore PE1’s behavior when receiving BUM packets in EVPN VPLS setups. Learn about non-DF roles, packet flooding, and ESI label usage in Nokia EVPN configurations.
Table of Contents
Question
Examine the exhibit. Which of the following actions is performed by PE1 after it receives a BUM packet from CE1?
A. PE1 does not flood the packet because PE1 is acting as non-designated forwarder (non-DF) for VPLS 10.
B. PE1 sends the packet to PE2 but not to PE3 because PE3 is connected to the originating ES.
C. PE1 sends the packet to PE2 and to PE3. An ESI label is included only in the packet sent to PE2.
D. PE1 sends the packet to PE2 and to PE3. An ESI label is included only in the packet sent to PE3.
Answer
A. PE1 does not flood the packet because PE1 is acting as non-designated forwarder (non-DF) for VPLS 10.
Explanation
In this EVPN (Ethernet VPN) VPLS (Virtual Private LAN Service) setup, we can see that PE1 is labeled as “Non-DF for EVI 10” (EVI stands for EVPN Instance). This designation is crucial for understanding PE1’s behavior when it receives a BUM (Broadcast, Unknown Unicast, and Multicast) packet from CE1.
In EVPN architectures, especially those with multi-homed sites, the concept of a Designated Forwarder (DF) is used to prevent loops and duplicate packet forwarding. Only the DF is responsible for forwarding BUM traffic from the EVPN core to the multi-homed Ethernet Segment (ES).
Since PE1 is explicitly labeled as a non-DF for VPLS 10, it means that it is not responsible for flooding BUM traffic for this particular EVPN instance. When PE1 receives a BUM packet from CE1, it will not forward this packet to other PEs in the EVPN core or back to the multi-homed segment.
This behavior is designed to prevent loops and ensure efficient traffic handling in multi-homed EVPN environments. The actual forwarding of the BUM traffic would be handled by the PE that is designated as the DF for VPLS 10, which is not shown in this diagram but would be either PE2 or PE3.
The other options are incorrect because:
B, C, and D all suggest that PE1 would forward the packet, which contradicts its role as a non-DF.
Understanding this concept is crucial for the Nokia 4A0-115 certification exam, as it demonstrates knowledge of EVPN VPLS operations and the role of Designated Forwarders in managing traffic in multi-homed environments.
Nokia 4A0-115 certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the Nokia 4A0-115 exam and earn Nokia 4A0-115 certification.