4A0-115: Nokia Ethernet Virtual Private Network ServicesDemo

By Nokia · Question Mode

QuestionQ3

Multi-Homing in EVPN

Referring to the exhibit, MAC1 moves from PE1 to PE2. Which of the following actions related to this MAC address mobility takes place?

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  • A CE1 generates an update message to PE1 withdrawing its MAC.
  • B PE1 generates an update message to remote PEs identifying the new location of CE1.
  • C PE2 advertises a MAC/IP route for MAC1 with a sequence number higher than that received from PE1.
  • D PE3 waits to receive a data packet from CE1 to update its FDB entry for MAC1.
Explanation

In EVPN (RFC 7432), MAC mobility is handled via the control plane using the MAC Mobility extended community attached to MAC/IP Advertisement routes. When PE2 detects that CE1 (and MAC1) has moved to its local segment, it advertises a MAC/IP route for MAC1 with a sequence number higher than the one previously advertised by PE1. This higher sequence number tells all other PEs in the EVPN instance that PE2's advertisement is the most current one, causing them to update their forwarding databases to point to PE2 and causing PE1 to withdraw its now-stale route for MAC1.

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