以太网环保护交换协议ERPS.ppt

G.8032Ethernet Ring Protection OverviewMarch, 2008ITU-T Q9 – SG 15 Agenda G.8032 Recommendation Introduction G.8032 Objectives and Principles G.8032 Concepts G.8032 Protection Switching G.8032 R-APS Messages G.8032 Items Under Study ITU-T SG15/Q9 G.8032 Recommendation G.8032 Recommendation consented February 2008 This Recommendation defines the APS protocol and protection switching mechanisms for ETH layer ring topologies. Included are details pertaining to bridged ring protection characteristics, architectures and the ring APS protocol. G.8032 Objectives and Principles Use of standard 802 MAC and OAM frames around the ring. Uses standard 802.1Q (and amended Q bridges), but with xSTP disabled. Ring nodes supports standard FDB MAC learning, forwarding, flush behaviour and port blocking/unblocking mechanisms. Prevents loops within the ring by blocking one of the links (either a pre-determined link or a failed link). Monitoring of the ETH layer for discovery and identification of Signal Failure (SF) conditions. Protection and recovery switching within 50 ms for typical rings. Total communication for the protection mechanism should consume a very small percentage of total available bandwidth. G.8032 Terms and Concepts Ring Protection Link (RPL) – Link designated by mechanism that is blocked during Idle state to prevent loop on Bridged ring RPL Owner – Node connected to RPL that blocks traffic on RPL during Idle state and unblocks during Protected state Link Monitoring – Links of ring are monitored using standard ETH CC OAM messages (CFM) Signal Fail (SF) – Signal Fail is declared when ETH trail signal fail condition is detected No Request (NR) – No Request is declared when there are no outstanding conditions (e.g., SF, etc.) on the node Ring APS (R-APS) Messages – Protocol messages defined in Y.1731 and G.8032 Automatic Protection Switching (APS) Channel - Ring-wide VLAN used exclusively for transmission of OAM messages including R-APS messages G.8032 Timers G