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Chapter 42 Diagnostic
VMG8825-B Series User’s Guide
305
42.6 OAM Ping
Click
Maintenance > Diagnostic > OAM Ping
to open the screen shown next. Use this screen to perform
an OAM (Operation, Administration and Maintenance) F4 or F5 loopback test on a PVC. The VMG sends
an OAM F4 or F5 packet to the DSLAM or ATM switch and then returns it to the VMG. The test result then
displays in the text box.
ATM sets up virtual circuits over which end systems communicate. The terminology for virtual circuits is as
follows:
Figure 192
Virtual Circuit Topology
Think of a virtual path as a cable that contains a bundle of wires. The cable connects two points and
wires within the cable provide individual circuits between the two points. In an ATM cell header, a VPI
(Virtual Path Identifier) identifies a link formed by a virtual path; a VCI (Virtual Channel Identifier)
identifies a channel within a virtual path. A series of virtual paths make up a virtual circuit.
F4 cells operate at the virtual path (VP) level, while F5 cells operate at the virtual channel (VC) level. F4
cells use the same VPI as the user data cells on VP connections, but use different predefined VCI values.
F5 cells use the same VPI and VCI as the user data cells on the VC connections, and are distinguished
Features
Select
Variable Retrieval
so the VMG can respond to requests for information, such
as requests for Ethernet counters and statistics, about link events.
Select
Link Events
so the VMG can interpret link events, such as link fault and dying
asp.Link events are set in event notification PDUs (Protocol Data Units), and indicate
when the number of errors in a certain given interval (time, number of frames,
number of symbols, or number of errored frame seconds) exceeds a specified
threshold. Organizations may create organization-specific link event TLVs as well.
Select
Remote Loopback
so the VMG can accept loopback control PDUs to convert
VMG into loopback mode.
Select
Active Mode
so the VMG initiates OAM discovery, send information PDUs; and
may send event notification PDUs, variable request/response PDUs, or loopback
control PDUs.
Apply
Click this button to save your changes.
Table 147 Maintenance > Diagnostics > 802.3ah
LABEL
DESCRIPTION
• Virtual Channel (VC)
Logical connections between ATM devices
• Virtual Path (VP)
A bundle of virtual channels
• Virtual Circuits
A series of virtual paths between circuit end points
Содержание VMG8825-B Series
Страница 15: ...15 PART I User s Guide...
Страница 65: ...65 PART II Technical Reference...
Страница 204: ...Chapter 17 Home Connectivity VMG8825 B Series User s Guide 204 Figure 115 Network Setting Home Connectivity...
Страница 231: ...Chapter 23 Voice VMG8825 B Series User s Guide 231 Figure 139 VoIP SIP SIP Account Add new account Edit...
Страница 236: ...Chapter 23 Voice VMG8825 B Series User s Guide 236 Figure 141 VoIP SIP SIP Service Provider Add new provider Edit...
Страница 297: ...Chapter 40 Firmware Upgrade VMG8825 B Series User s Guide 297 Figure 182 Error Message...
Страница 313: ...313 PART III Appendices Appendices contain general information Some information may not apply to your device...
Страница 360: ...Index VMG8825 B Series User s Guide 360 Z ZyXEL Family Safety page 217...