Diagnostic; Chapter 35 Diagnostic; Overview; What You Can Do In This Chapter - ZyXEL Communications VMG1312-B Series User Manual

35.1 Overview

The D ia gnost ic screens display inform at ion t o help you ident ify problem s wit h t he Device.
The rout e bet ween a CO VDSL swit ch and one of it s CPE m ay go t hrough swit ches owned by
independent organizat ions. A connect ivit y fault point generally t akes t im e t o discover and im pact s
subscriber 's net work access. I n order t o elim inat e t he m anagem ent and m aint enance effort s, I EEE
802.1ag is a Connect ivit y Fault Managem ent ( CFM) specificat ion which allows net work
adm inist rat ors t o ident ify and m anage connect ion fault s. Through discovery and verificat ion of t he
pat h, CFM can det ect , analyze and isolat e connect ivit y fault s in bridged LANs.

35.1.1 What You Can Do in this Chapter

• The Pin g & Tr a ce Rou t e & N sLook up screen let s you ping an I P address or t race t he rout e
packet s t ake t o a host (
• The 8 0 2 .1 a g screen let s you perform CFM act ions (
• The OAM Ping Te st screen let s you send an ATM OAM ( Operat ion, Adm inist rat ion and
Maint enance) packet t o verify t he connect ivit y of a specific PVC. (

35.2 What You Need to Know

The following t erm s and concept s m ay help as you read t hrough t his chapt er.
How CFM Works
A Maint enance Associat ion ( MA) defines a VLAN and associat ed Maint enance End Point ( MEP) port s
on t he device under a Maint enance Dom ain ( MD) level. An MEP port has t he abilit y t o send
Connect ivit y Check Messages ( CCMs) and get ot her MEP port s inform at ion from neighbor devices'
CCMs wit hin an MA.
CFM provides t wo t est s t o discover connect ivit y fault s.
• Loopback t est - checks if t he MEP port receives it s Loop Back Response ( LBR) from it s t arget
aft er it sends t he Loop Back Message ( LBM) . I f no response is received, t here m ight be a
connect ivit y fault bet ween t hem .
• Link t race t est - provides addit ional connect ivit y fault analysis t o get m ore inform at ion on where
t he fault is. I f an MEP port does not respond t o t he source MEP , t his m ay indicat e a fault .
Adm inist rat ors can t ake furt her act ion t o check and resum e services from t he fault according t o
t he line connect ivit y st at us report .
VMG1312-B Series User's Guide
C
HAPTER
Sect ion 35.3 on page 285) .

Diagnostic

Sect ion 35.5 on page 287) .
Sect ion 35.5 on page
3 5
287) .
284