Diagnostic
Diagnostic Overview
The Diagnostic screen displays information to help you identify Internet connection problems with the Zyxel Device.
The route between an Ethernet switch and one of its Customer-Premises Equipment (CPE) may go through switches owned by independent organizations. A connectivity fault point generally takes time to discover and impacts subscriber’s network access. In order to eliminate the management and maintenance efforts, IEEE 802.1ag is a Connectivity Fault Management (CFM) specification which allows network administrators to identify and manage connection faults. Through discovery and verification of the path, CFM can detect, analyze and isolate connectivity faults in bridged LANs.
What You Can Do in this Chapter
• The Ping&Traceroute&Nslookup screen lets you ping an IP address or trace the route packets take to a host (Diagnostic).
• The OAM Ping screen lets you send an ATM OAM (Operation, Administration and Maintenance) packet to verify the connectivity of a specific PVC (OAM Ping).
What You Need to Know
The following terms and concepts may help as you read through this chapter.
How CFM Works
A Maintenance Association (MA) defines a VLAN and associated Maintenance End Point (MEP) ports on the device under a Maintenance Domain (MD) level. An MEP port has the ability to send Connectivity Check Messages (CCMs) and get other MEP ports information from neighbor devices’ CCMs within an MA.
CFM provides two tests to discover connectivity faults.
• Loopback test – checks if the MEP port receives its Loop Back Response (LBR) from its target after it sends the Loop Back Message (LBM). If no response is received, there might be a connectivity fault between them.
• Link trace test – provides additional connectivity fault analysis to get more information on where the fault is. If an MEP port does not respond to the source MEP, this may indicate a fault. Administrators can take further action to check and resume services from the fault according to the line connectivity status report.
Diagnostic
Use this screen to ping, traceroute or nslookup for troubleshooting. Ping and traceroute are used to test whether a particular host is reachable. After entering an IP address and clicking one of the buttons to start a test, the results will be shown in the screen. Use nslookup to find the IP address for a host name and the host name for an IP address. Use TR-471 test to perform an Internet connection quality test through a TR-471 test server for applications such as live streaming, online games and VoIP.
Click Maintenance > Diagnostic to open the following screen.
Maintenance > Diagnostic
The following table describes the fields in this screen.
Label | Description |
|---|---|
Ping/TraceRoute Test | The result of tests is shown here in the info area. |
Select Test Method | |
Ping | Select this to perform a ping test on the IPv4 address or host name in order to test a connection. The ping statistics will show in the info area. |
Ping 6 | Select this to perform a ping test on the IPv6 address or host name in order to test a connection. The ping statistics will show in the info area. |
Trace Route | Select this to perform the IPv4 trace route function. This determines the path a packet takes to the specified host. |
Trace Route 6 | Select this to perform the IPv6 trace route function. This determines the path a packet takes to the specified host. |
Nslookup | Select this to perform a DNS lookup on the IP address or host name. |
TCP/IP | |
Address | Enter the IP address of a computer that you want to perform ping, trace route or nslookup in order to test a connection. |
802.1ag (CFM)
Click Maintenance > Diagnostic > 802.1ag to open the following screen. Use this screen to configure and perform Connectivity Fault Management (CFM) actions as defined by the IEEE 802.1ag standard. CFM protocols include Continuity Check Protocol (CCP), Link Trace (LT), and Loopback (LB).
Maintenance > Diagnostic > 802.1ag
The following table describes the fields in this screen.
Label | Description |
|---|---|
802.1ag Connectivity Fault Management | |
IEEE 802.1ag CFM | Click this switch to enable or disable the IEEE802.1ag CFM specification, which allows network administrators to identify and manage connection faults. When the switch goes to the right  , the function is enabled. Otherwise, it is not. |
Y.1731 | Click this switch to enable or disable Y.1731, which monitors Ethernet performance. When the switch goes to the right  , the function is enabled. Otherwise, it is not. |
Interface | Select the interface on which you want to enable the IEE 802.1ag CFM. |
Maintenance Domain (MD) Level | Select a level (0 – 7) under which you want to create an MA. |
MEG ID | Enter a descriptive name to identify the Maintenance Entity Group (MEG). This field only appears if the Y.1731 field is enabled. |
MD Name | Enter a descriptive name for the Maintenance Domain (MD). This field only appears if the Y.1731 field is disabled. |
MA ID | Enter a descriptive name to identify the Maintenance Association (MA). This field only appears if the Y.1731 field is disabled. |
MEG ID | Enter a descriptive name to identify the Maintenance Entity Group (MEG). This field only appears if the Y.1731 field is enabled. |
802.1Q VLAN ID | Enter a VLAN ID (1 – 4094) for this MA. |
Local MEP ID | Enter the local Maintenance Endpoint (MEP) Identifier (1 – 8191). |
CCM | Click the switch to the right  to continue sending MEP information by Connectivity Check Messages (CCM).When CCMs are received the Zyxel Device will always process it, whether CCM is enabled or not. |
Remote MEP ID | Enter the remote Maintenance Endpoint Identifier (1 – 8191). |
Test the connection to another Maintenance End Point (MEP) | |
Destination MAC Address | Enter the target device’s MAC address to which the Zyxel Device performs a CFM loopback and linktrace test. |
Test Result | |
Loopback Message (LBM) | This shows Pass if a Loop Back Messages (LBMs) responses are received. If LBMs do not get a response it shows Fail. |
Linktrace Message (LTM) | This shows the MAC address of MEPs that respond to the LTMs. |
Apply | Click this button to save your changes. |
Send Loopback | Click this button to have the selected MEP send the LBM to a specified remote end point. |
Send Linktrace | Click this button to have the selected MEP send the LTMs to a specified remote end point. |
802.3ah (OAM)
Click Maintenance > Diagnostic > 803.ah to open the following screen. Link layer Ethernet OAM (Operations, Administration and Maintenance) as described in IEEE 802.3ah is a link monitoring protocol. It utilizes OAM Protocol Data Units (OAM PDU’s) to transmit link status information between directly connected Ethernet devices. Both devices must support IEEE 802.3ah.
Maintenance > Diagnostic > 802.3ah
The following table describes the labels in this screen.
LABEL | DESCRIPTION |
|---|---|
IEEE 802.3ah Ethernet OAM | Click this switch to enable or disable the Ethernet OAM on the specified interface. When the switch goes to the right  , the function is enabled. Otherwise, it is not. |
Interface | Select the interface on which you want to enable the IEEE802.3ah. |
OAM ID | Enter a positive integer to identify this node. |
Auto Event | Click this switch to detect link status and send a notification when an error (such as errors in symbol, frames, or seconds) is detected. Otherwise, disable this and you will not be notified. When the switch goes to the right  , the function is enabled. Otherwise, it is not. |
Features | Select Variable Retrieval so the Zyxel Device can respond to requests for information, such as requests for Ethernet counters and statistics, about link events. Select Link Events so the Zyxel Device 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 error frame seconds) exceeds a specified threshold. Organizations may create organization-specific link event TLVs as well. Select Remote Loopback so the Zyxel Device can accept loopback control PDUs to convert Zyxel Device into loopback mode. Select Active Mode so the Zyxel Device initiates OAM discovery, send information PDUs; and may send event notification PDUs, variable request and response PDUs, or loopback control PDUs. |
Apply | Click this button to save your changes. |
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 DX5301-B2/B3 sends an OAM F4 or F5 packet to the DSLAM or ATM switch and then returns it to the DX5301-B2/B3. 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:
• 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
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 from data cells by a predefined Payload Type Identifier (PTI) in the cell header. Both F4 flows and F5 flows are bidirectional and have two types.
• segment F4 flows (VCI=3)
• end-to-end F4 flows (VCI=4)
• segment F5 flows (PTI=100)
• end-to-end F5 flows (PTI=101)
OAM F4 or F5 tests are used to check virtual path or virtual channel availability between two DSL devices. Segment flows are terminated at the connecting point which terminates a VP or VC segment. End-to-end flows are terminated at the end point of a VP or VC connection, where an ATM link is terminated. Segment loopback tests allow you to verify integrity of a PVC to the nearest neighboring ATM device. End-to-end loopback tests allow you to verify integrity of an end-to-end PVC.
The DSLAM to which the DX5301-B2/B3 is connected must also support ATM F4 and/or F5 to use this test.This screen is available only when you configure an ATM layer-2 interface using DX5301-B2/B3.Maintenance > Diagnostic > OAM Ping
The following table describes the labels in this screen.
LABEL | DESCRIPTION |
|---|---|
Select a PVC on which you want to perform the loopback test. | |
F4 segment | Press this to perform an OAM F4 segment loopback test. |
F4 end-end | Press this to perform an OAM F4 end-to-end loopback test. |
F5 segment | Press this to perform an OAM F5 segment loopback test. |
F5 end-end | Press this to perform an OAM F5 end-to-end loopback test. |