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Extreme Fabric (Fabric Connect) study materials
Extreme Fabric (Fabric Connect) study resources

Extreme Fabric (Fabric Connect): Fabric operations and troubleshooting

Extreme Fabric (Fabric Connect) · Work through your exam, one topic at a time.

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Fabric operations and troubleshooting

Domain 3 tests structured day-2 work: prove adjacency, nickname and I-SID state before chasing MAC addresses, then decide whether the fault is control plane (IS-IS), service binding (VLAN, I-SID, port membership) or edge attachment (FA, UNI auth). Expect output-reading items where a single line tells you the fault is one-ended.

Health checks in order

  • show isis adj and show isis spbm: all expected system-ids present, one nickname per node, both B-VIDs listed.
  • show isis spbm i-sid <isid>: the service must be active at both ends. Active at one end only means the far end lost its binding.
  • show isis interface and show isis lsdb: metric changes, missing links, unexpected topology.
  • show mac-address-table, show ip arp, show ip route vrf <name>: forwarding state after the control plane is clean.
  • show smlt, show ist / show vist, show fa assignment: edge cluster and attachment health.

Isolation logic

  1. Link state and MTU. 2. IS-IS adjacency and authentication. 3. Nickname conflict - look for log entries and MACs that keep moving. 4. I-SID active or not. 5. VLAN membership and port membership at both ends. 6. FA/UNI authentication outcome. 7. For Fabric Extend, the underlying IP path and any IPsec tunnel.

Worked example

Two hosts in the same L2 VSN cannot communicate. Adjacency is full on every node, both B-VIDs are present, and show isis spbm i-sid reports the I-SID active on BEB-A but absent on BEB-B. That single asymmetry rules out IS-IS and pointing at the backbone: the far BEB is not advertising the service, which happens when the VLAN was deleted or recreated without the vlan i-sid binding, or the UNI port was left in a different VLAN. Re-bind the I-SID, confirm the I-SID is active at both ends, then check that the MACs appear.

Traps that cost marks

Reading show isis spbm as "the service is up"; checking the global routing table when the service lives in a VRF; blaming SPB for a Fabric Extend MTU black hole (small pings work, large ones vanish); assuming an I-SID implies IGMP snooping behaviour; ignoring timestamps when correlating flaps with a change window; mistaking a one-way UNI authentication failure for a fabric failure.