HP 6125G HP 6125G & 6125G/XG Blade Switches High Availability Configur - Page 24

configured on the ports of device A through device F. Port 1 of device B is configured with the following MPs-a level 5 MIP, a level 3 inward-facing MEP, a level 2 inward-facing MEP, and a level 0 outward-facing MEP. Figure 5 CFD grading example MEP list A MEP list is a collection of configurable local MEPs and the remote MEPs to be monitored in the same MA. It lists all MEPs configured on different devices in the same MA. The MEPs all have unique MEP IDs. When a MEP receives from a remote device a continuity check message (CCM) with a MEP ID not included in the MEP list of the MA, it drops the message. CFD functions CFD works effectively only in properly configured networks. Its functions, which are implemented through the MPs, include: • Continuity check (CC) • Loopback (LB) • Linktrace (LT) CC Connectivity faults are usually caused by device faults or configuration errors. CC examines the connectivity between MEPs. This function is implemented through periodic sending of continuity check messages (CCMs) by the MEPs. A CCM sent by one MEP is intended to be received by all of the other MEPs in the same MA. If a MEP fails to receive the CCMs within 3.5 times the sending interval, the link is considered faulty and a log is generated. When multiple MEPs send CCMs at the same time, the multipoint-to-multipoint link check is achieved. CCM frames are multicast frames. LB Similar to ping at the IP layer, LB verifies the connectivity between a source device and a target device. To implement this function, the source MEP sends loopback messages (LBMs) to the target MEP. 17