Extreme Fabric (Fabric Connect) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

SPB

Shortest Path Bridging, an IEEE 802.1aq technology that builds a loop-free fabric using IS-IS and forwards customer traffic over a MAC-in-MAC core by I-SID.

I-SID

A 24-bit service identifier that names a Layer 2 service instance; edge nodes map customer VLANs to I-SIDs and the core forwards by I-SID.

BEB

Backbone Edge Bridge: a fabric node that connects customer access ports, performs VLAN-to-I-SID mapping, and encapsulates frames into the SPB backbone.

BCB

Backbone Core Bridge: an SPB node that only forwards backbone traffic by B-MAC and B-VLAN and does not attach customer access ports.

Nickname

A unique 20-bit identifier assigned to each SPB node, used in the data plane to identify the source and destination edge for a service.

B-VLAN

Backbone VLAN used inside the SPB core to carry I-SID traffic; I-SIDs are distributed across configured B-VLANs for load sharing.

VLAN-to-I-SID mapping

The BEB configuration that binds a customer VLAN on an access port to an I-SID so the service is extended across the fabric.

SMLT

Split Multi-Link Trunking: two cluster peers present a single logical LAG to a dual-homed access switch, giving active-active redundancy without STP blocking.

IST

Inter-Switch Trunk: the link between SMLT cluster peers that carries control traffic and keeps the cluster synchronized; it must be redundant.

RSMLT

Routed SMLT: both cluster peers hold the same gateway IP and forward for each other, so a peer failure does not break the default gateway.

IS-IS in SPB

SPB uses IS-IS with SPB extensions as its control plane to distribute topology, nicknames, and I-SID membership across all fabric nodes.

SPB MTU overhead

SPB encapsulation adds 22 bytes of outer header, so fabric and access links must support the largest customer frame plus 22 bytes.

Adjacency check

Verify IS-IS neighbor state on every fabric link; a down adjacency stops SPB topology and I-SID propagation along that path.

I-SID missing symptom

If a remote BEB lacks the I-SID, check the local VLAN-to-I-SID mapping and whether the I-SID was advertised through IS-IS.

SMLT blackhole cause

Traffic drops on a dual-homed access switch usually mean IST down, mismatched SMLT IDs, or one peer missing the SMLT client port.

SPB MAC table

Shows customer MACs learned with the edge nickname; a MAC learned on the wrong edge suggests a loop or mis-mapped I-SID.

MTU symptom

Large frames failing while small pings succeed points to SPB's 22-byte overhead exceeding link MTU; check jumbo settings end to end.

Adjacency flap cause

Repeated IS-IS adjacency flaps usually trace to physical errors, MTU mismatch, duplicate nicknames, or authentication mismatch on the link.

IS-IS authentication

Apply MD5 or HMAC authentication on fabric links so unauthorized nodes cannot inject topology or nickname information into the fabric.

Nickname conflict

Two nodes advertising the same nickname cause traffic misdirection; enforce unique allocation and alert on nickname conflict alarms.

IST failure risk

An IST failure splits the SMLT cluster and can create a Layer 2 loop if access switches remain dual-homed; keep IST on redundant links.

RSMLT failover

With RSMLT, a peer failure keeps the gateway IP reachable because the surviving peer forwards for the failed peer's subnet.

Edge port security

On BEB access ports apply ACLs and DHCP snooping so the fabric core carries only intended I-SID traffic, not unfiltered customer broadcasts.

Management hardening

Restrict management access to fabric loopback addresses, use protected in-band or out-of-band management, and disable unused services on nodes.

Config templating

Template common fabric parameters such as IS-IS area, MTU, B-VLANs, and authentication; vary only node-specific values like sys-id, nickname, and loopback.

Idempotent automation

Scripts should read current state before applying changes so re-runs do not create duplicate nicknames, I-SID mappings, or SMLT memberships.

Nickname registry

A central allocation record for nicknames and I-SIDs that prevents collisions as fabric nodes and services are added.

Automation validation gate

After automation runs, require end-to-end tests such as cross-I-SID ping and remote BEB MAC learning before marking the change successful.

Fabric monitoring poll

Schedule polling of IS-IS neighbor state, SPB nickname table, I-SID database, and SMLT/IST status; alert on adjacency loss and conflicts.

Config backup rule

Export running configuration and topology data after every change so a failed fabric node can be rebuilt to match the existing fabric.

SPB deployment order

Configure IS-IS and SPB on core nodes first, verify adjacency and LSDB convergence, then add BEB edge nodes and map I-SIDs.

Loop-free by design

SPB forwards along IS-IS shortest paths and is loop-free without STP; broadcast storms suggest misconfigured access ports or an outside L2 path.