FCoE FC-Map Configuration to Prevent Cross-Fabric Talk

350-601 By islever Editorial Last updated

Implement Fibre Channel

Short answer

D The fcoe fcmap command assigns an FC-Map that identifies the fabric and discards MAC addresses not part of the current fabric while QoS is preserved.

Question

An engineer implements an environment with multiple traffic types on a consolidated I/O link between Cisco Nexus 9000 Series Switch and MDS 9000 Series Switch. The configuration must meet these requirements: • The unified I/O link must support LAN and SAN traffic. • A single, multipurpose Ethernet transport must be used. • The configuration must discard MAC addresses that are not part of the current fabric. • The QoS markings must be preserved. Which configuration set meets the requirements?
  1. MDS-A(config)# interface fcip4 -
  2. N9K-2(config)# interface Eth2 -
  3. MDS-B(config)# interface fc3 -
  4. N9K-1(config)# fcoe fcmap 0e.fc.1d Correct Answer

Key Takeaways

Configuring fcoe fcmap makes the switch discard MAC addresses not part of the current fabric; this is the FCoE fabric-isolation mechanism and works with the existing network-qos class for QoS.

On a converged Nexus link, fcoe fcmap sets the FC-Map that identifies the fabric and discards FCoE frames from foreign fabrics, preventing cross-fabric data corruption while preserving QoS.

Common mistake: Pointing at an fcip interface, a plain Ethernet interface, or a native MDS fc interface instead of the Nexus unified-link fcoe fcmap setting that performs fabric segregation.

Expert Analysis

Why the Answer Is Correct

On a converged Nexus 9000 link carrying both LAN and SAN, configuring fcoe fcmap <value> sets the global FC-Map that identifies the Fibre Channel fabric for that switch. When the FC-Map is configured, the switch discards FCoE frames whose MAC addresses are not part of the current fabric, preventing cross-fabric data corruption. QoS markings on the Ethernet transport are preserved because FCoE uses the existing network-qos class.

Why the Other Options Are Wrong

A. An fcip interface is for FCIP tunneling over IP, unrelated to fabric isolation on a unified link. B. A plain Ethernet interface (Eth2) does not enforce FC-Map-based fabric segregation. C. An fc interface on the MDS is a native Fibre Channel port, not the FCoE unified-link FC-Map setting.

Community Comment Notes

Votes D 67 / B 33. Arch_Angel (3 likes) and bizzar7774 quote the NX-OS SAN Switching Guide: the FC-Map "discards the MAC addresses that are not part of the current fabric." Gopz28's B answer is refuted because auto-qos alone does not perform fabric segregation.

Official Reference

https://www.cisco.com/c/en/us/td/docs/dcn/nx-os/nexus9000/101x/configuration/san-switching/cisco-nexus-9000-series-nx-os-san-switching-configuration-guide-101x/m-configuring-fc-fcoe-switch-mode.html

This link opens the official vendor documentation in a new tab.

Community Votes

D
67%
B
33%

67% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 6 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 6

  1. Arch_Angel 👍 3
    Answer is D Configuring the FC-Map You can prevent data corruption due to cross-fabric talk by configuring an FC-Map that identifies the Fibre Channel fabric for this switch. When the FC-Map is configured, the switch discards the MAC addresses that are not part of the current fabric.
  2. bizzar7774 👍 1 Answered D
    You can prevent data corruption due to cross-fabric talk by configuring an FC-Map that identifies the Fibre Channel fabric for this Cisco Nexus device. When the FC-Map is configured, the switch discards the MAC addresses that are not part of the current fabric. ( https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/93x/san_switching/configuration/guide/b-cisco-nexus-9000-nx-os-san-switching-configuration-guide-933/m-n9000-san-s-enabling-feature-fcoe.html )
  3. Gopz28 👍 1 Answered B
    An interface has to be trunk and qos marking is perserved with Auto qos hence answer is B
  4. udo2020 👍 1
    A must be wrong because it is for SPAN sessions. B and C are wrong so it should be D!
  5. crooks_1988 👍 1
    I agree with D, also auto-qos command does not exist on MDS 9000 CLI reference guide
Show 1 more comment
  1. asd248402 👍 1 Answered D
    fcmap is neeed for segragation

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