Specifications

Fault Detection and Recovery

ExtremeWare XOS 11.0 Concepts Guide 179

Figure 12: EAPS fault detection and protection switching

Ring Port Down Event Sent by Hardware Layer

When a ring port goes down on a master node switch, it is notified by the lower hardware layer and

immediately goes into a “failed” state.

If the ring port that goes down on the master node is the primary port, the secondary port is opened.

The normal operation of flushing the master node’s FDB and sending a “flush FDB” message to all

transit nodes is performed.

Polling

The master node transmits a health check packet on the control VLAN at a user-configurable interval

(see Figure 11). If the ring is complete, the master node receives the health-check packet on its secondary

port (the control VLAN is not blocked on the secondary port). When the master node receives the

health-check packet, it resets its failtimer and continues normal operation.

If the master node does not receive the health check packet before the failtimer interval expires and the

failtime expiry action is set to

open-secondary-port, it declares a “failed” state and performs the same

steps described above:

• Unblocks its secondary port for access by the protected VLANs.

• Flushes its forwarding database (FDB).

• Sends a “flush FDB” message to its associated transit nodes.

Restoration Operations

The master node continues sending health check packets out its primary port even when the master

node is operating in the failed state. As long as there is a break in the ring, the fail period timer of the

master node continues to expire, and the master node remains in the failed state.

EW_072

S3 sends "link down"

message to

master node

Master

node

Break

in ring

Master node opens secondary port

to allow traffic to pass

S4 sends "link down"

message to master node