Diagnostic Screens; Cfm Overview; How Cfm Works - ZyXEL Communications MSC1000G User Manual

This chapter explains the Diagnostic screens.

6.1 CFM Overview

The route between a CO network and one of a CPE user may go through aggregated switches,
routers and/or DSLAMs owned by independent organizations. A connectivity fault point generally
takes time to discover and impacts on subscribers' network access. In order to reduce management
and maintenance requirements, the IEEE 802.1ag Connectivity Fault Management (CFM)
specification was developed to allow network administrators to identify and manage connection
faults. Through discovery and verification of packet paths, CFM can detect and analyze connectivity
faults in bridged LANs.
The figure shown below is an example of a connection fault between switches on the LAN. CFM can
be used to identify and manage this kind of connection problem.
Figure 86 Management for any Fault in Bridges
CPE

6.1.1 How CFM Works

To enable CFM, a pro-active Connectivity Check (CC) between two CFM-aware devices in the same
MD (Maintenance Domain) network takes place. An MA (Maintenance Association) defines a VLAN
and associated ports on the device under an MD level. In this MA, a port can be an MEP
(Maintenance End Point) port or an MIP (Maintenance Intermediate Point) port.
• MEP port - has the ability to send pro-active connectivity check (CC) packets and get other MEP
ports information from the CC packets of neighboring switches within an MA.
• MIP port - only forwards the CC packets.
Management Switch Card User's Guide
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Diagnostic Screens

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