Extreme Data Center Fabric Architecture and VOSS/VSP Fundamentals
This domain checks that you can describe the Extreme Data Center fabric in the platform's own terms and place each device role correctly.
Roles and port types
- BEB (Backbone Edge Bridge) attaches services: it maps a local VLAN or port to an I-SID and encapsulates frames in MAC-in-MAC (802.1ah).
- BCB (Backbone Core Bridge) is transit only: it runs IS-IS and SPBM and forwards backbone MAC addresses; it holds no service configuration.
- NNI (fabric) ports run IS-IS/SPBM toward other VSPs. UNI (access) ports face servers, switches and phones, carrying VLANs or a transparent port.
- The control plane is IS-IS (802.1aq SPB uses it to advertise nodes, nicknames and I-SIDs); the data plane is shortest-path forwarding over B-MACs, with ECMP across equal-cost paths.
Identifiers you must keep straight
- System ID - the 6-byte IS-IS identity, normally derived from the chassis MAC.
- Nickname - the fabric-unique decimal name of the node; duplicate nicknames break forwarding.
- I-SID - a 24-bit service identifier (1-16,777,215) that is globally significant and must match on every BEB that terminates the service.
- B-VID / B-VLAN - the backbone VLAN that carries encapsulated traffic; it must be consistent across the fabric. The local VLAN ID is only locally meaningful, which is why two sites can use VLAN 10 and VLAN 110 for the same service.
VOSS and VSP
VOSS is the operating system on the VSP 4000/7000/8000 families and on virtual vVOSS; its CLI moves from User mode to Privileged (enable) to Global Configuration (configure terminal). Fabric configuration is done from configuration mode, and nothing is persistent until save config.
Worked example
A design uses four spine switches as BCBs and eight leaf VSPs as BEBs for 200 Layer 2 services. Each leaf pair needs vlan create, vlan members add and vlan i-sid <vlan> <i-sid> for its services; each spine needs only a unique nickname, the same B-VID, and IS-IS/SPBM on its fabric ports. If an engineer pastes vlan i-sid 100 10100 onto a spine, that spine becomes a BEB for the service and starts terminating traffic - a common outage cause. Reasoning: I-SID configuration defines service attachment; IS-IS/SPBM forwarding alone defines transit.
Traps
Assuming every VSP in the fabric needs the service VLANs; treating SPB as a VLAN-based transport that needs STP; forgetting that the B-VID must match; confusing VOSS syntax with EXOS (Fabric Engine) syntax; and believing a nickname is automatically unique once IS-IS is up.