How Is a Server Learned on a vPC Peer Leaf in Cisco ACI?
An engineer configures two Cisco ACI leaf switches called Leaf1 and Leaf2 as VPC peers. The server called S1 is connected to Leaf1 with a port channel interface. How is S1 learned in the endpoint table of Leaf2?
Community Votes
67% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
The question tests whether you can separate local, remote, on-peer, and bounce endpoint types in the ACI endpoint table; the trap is assuming that any endpoint not learned locally by Leaf2 must simply be a remote endpoint.
When server S1 attaches to Leaf1 through a non-vPC port channel while Leaf1 and Leaf2 are vPC peers, Leaf2 programs S1 in its endpoint table as an on-peer endpoint rather than a local or plain remote entry. This page confirms why option D is the correct 300-620 answer and how ACI classifies synchronized vPC endpoint entries.
Choosing A (remote endpoint) because Leaf2 never saw S1's traffic in its own data plane — but entries synced from a vPC peer leaf are specifically flagged as on-peer, a distinct subtype of remote.
Community Discussion (3 comments)
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Expert Analysis
Why the Answer Is Correct
Leaf1 and Leaf2 form a vPC pair, yet S1 is attached only to Leaf1 through a port channel, so from the fabric's perspective S1 sits on a non-vPC (orphan-style) port of a vPC peer leaf. Leaf1 learns S1 locally in its own endpoint table through data-plane learning, then synchronizes that MAC and IP address to Leaf2 across the vPC peer link using COOP control-plane messaging. Because the entry arrives from a vPC peer instead of from an unrelated remote leaf, APIC records it on Leaf2 as an on-peer endpoint — the special synchronized entry that points back to a port on the peer leaf. That on-peer label is exactly the state the question describes, which makes option D the correct classification over the plain remote endpoint option.Why the Other Options Are Wrong
A (remote endpoint) is the deliberate distractor: remote entries are learned from leaf switches that are not vPC peers, and the scenario explicitly states that Leaf1 and Leaf2 are vPC peers, which is precisely why the on-peer subtype applies instead. C (local endpoint) would require S1 to be attached to Leaf2 itself, either directly or through a member link of a vPC port channel spanning both leaves, but the question says the port channel is on Leaf1 only. B (bounce entry endpoint) describes a transient entry created after an endpoint moves or its MAC flaps so traffic is not black-holed while it is re-learned; nothing in the scenario indicates a move, so it cannot be the steady-state classification for S1.Community Comment Notes
Most learners who picked D follow mdriraa's reasoning that the on-peer endpoint is "a variant of the remote endpoint", reserved for entries learned through "vPC synchronization on the control plane" rather than data-plane learning, which matches S1 sitting on a non-vPC port of a vPC peer. prospio971 first argued for A as a remote entry, then posted the D explanation himself, showing how easily the remote versus on-peer distinction trips people up when they focus only on the fact that Leaf2 did not learn S1 locally. Roughly a third of voters stayed with A because a synchronized entry looks remote at first glance; the deciding detail in the stem is the explicit vPC peering between Leaf1 and Leaf2.Exam Strategy
Before answering, map each option to a one-line definition: local = attached to this leaf (or a member link of a vPC spanning both leaves), remote = learned via COOP from a non-vPC-peer leaf, on-peer = synchronized from a vPC peer, bounce = transient entry after a move or flap. Underlining the phrases "vPC peers" and "connected to Leaf1" in the stem usually collapses the choice to on-peer within seconds.
Frequently Asked Questions
Why is S1 not simply a remote endpoint in Leaf2's endpoint table?
Plain remote entries come from leaf switches that are not vPC peers; because Leaf1 is Leaf2's vPC peer, the synchronized entry is flagged on-peer, a special variant of remote.
When would S1 show up as a bounce entry endpoint instead of an on-peer endpoint?
A bounce entry is a temporary entry created after an endpoint move or MAC flap to avoid black-holing traffic until the endpoint is re-learned; S1 is stable here, so it is not bounce.