Oam Ping Test - ZyXEL Communications VMG1312-B Series User Manual

35.5 OAM Ping Test

Click M a int e na nce > D ia gnost ic > OAM Ping Te st t o open t he screen shown next . Use t his
screen t o perform an OAM ( Operat ion, Adm inist rat ion and Maint enance) F4 or F5 loopback t est on a
PVC. The Device sends an OAM F4 or F5 packet t o t he DSLAM or ATM swit ch and t hen ret urns it t o
t he Device. The t est result t hen displays in t he t ext box.
ATM set s up virt ual circuit s over which end syst em s com m unicat e. The t erm inology for virt ual
circuit s is as follows:
• Virt ual Channel ( VC)
• Virt ual Pat h ( VP)
• Virt ual Circuit s
Figure 147 Virt ual Circuit Topology
Think of a virt ual pat h as a cable t hat cont ains a bundle of wires. The cable connect s t wo point s and
wires wit hin t he cable provide individual circuit s bet ween t he t wo point s. I n an ATM cell header, a
VPI ( Virt ual Pat h I dent ifier) ident ifies a link form ed by a virt ual pat h; a VCI ( Virt ual Channel
I dent ifier) ident ifies a channel wit hin a virt ual pat h. A series of virt ual pat hs m ake up a virt ual
circuit .
F4 cells operat e at t he virt ual pat h ( VP) level, while F5 cells operat e at t he virt ual channel ( VC)
level. F4 cells use t he sam e VPI as t he user dat a cells on VP connect ions, but use different
predefined VCI values. F5 cells use t he sam e VPI and VCI as t he user dat a cells on t he VC
connect ions, and are dist inguished from dat a cells by a predefinded Payload Type I dent ifier ( PTI ) in
t he cell header. Bot h F4 flows and F5 flows are bidirect ional and have t wo t ypes.
• segm ent F4 flows ( VCI = 3)
• end- t o- end F4 flows ( VCI = 4)
• segm ent F5 flows ( PTI = 100)
• end- t o- end F5 flows ( PTI = 101)
OAM F4 or F5 t est s are used t o check virt ual pat h or virt ual channel availabilit y bet ween t wo DSL
devices. Segm ent flows are t erm inat ed at t he connect ing point which t erm inat es a VP or VC
segm ent . End- t o- end flows are t erm inat ed at t he end point of a VP or VC connect ion, where an ATM
link is t erm inat ed. Segm ent loopback t est s allow you t o verify int egrit y of a PVC t o t he nearest
neighboring ATM device. End- t o- end loopback t est s allow you t o verify int egrit y of an end- t o- end
PVC.
Not e: The DSLAM t o w hich t he Device is connect ed m ust also support ATM F4 and/ or F5
t o use t his t est .
VMG1312-B Series User's Guide
Logical connect ions bet ween ATM devices
A bundle of virt ual channels
A series of virt ual pat hs bet ween circuit end point s
Chapter 35 Diagnostic
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