METHOD AND ARRANGEMENT FOR FAILURE HANDLING IN A NETWORK

摘要

The invention relates to failure handling in a tree sructure network (NW1) that has edge nodes (EN1...EN4) and switching nodes (SW1...SW4) interconnected by lines (L1). VLANs (VLAN1-VLAN3) are established such that at least one thereof provides connectivity in case of any single failure in the network. The VLANs can be established by using spanning trees (ST1,ST2,ST3). Among the edge nodes, emitters (EN3) broadcast alive messages (Ai,A2,A3) regularly on the VLANs and notifiers (EN2) note the alive messages. A missing alive message indicates a failure (CD1) on one VLAN (VLAN2) and the notifier (EN2) broadcasts corresponding failure messages (F1,F2,F3) on the VLANs. When all the alive messages(Al,A2,A3) appear again the notifier (EN2) broadcasts corresponding repair messages (R1,R2,R3). If the notifiers don't note a failure the nodes (EN1,EN4) with no special role performs a similar function as the notifier (EN2) somewhat slower. The failure handling is fast, robust, uses few messages, increases only slightly the traffic load in the network (NW1) and is compliant with present standards.