E3Switch DS3 Operating information manual - page 22
Chapter 10: Troubleshooting
Step-by-Step Diagnosis
This section assumes that communication between two machines at opposite ends of the E3, T3/DS3 link
(herein the link) is failing. If this is a test in the laboratory or without a telecom link present, be sure to read
the previous “Laboratory Testing” section first.
1. If access to the HTTP management interface of the converter is possible, many useful status messages
will be displayed. Typically, any message highlighted in orange should be of concern. Error counters
are of lesser concern if they are not incrementing, and some link errors would be normal as link cables
are initially connected.
2. The DS3/E3 BER light of the converter should be illuminated and green. This indicates that a valid,
DS3/E3 waveshape is being received without bit errors and with proper framing. Refer to the front
panel section of this document for other light colors.
The DS3/E3 port light of the converter should be illuminated and green. This indicates that a valid,
framed carrier signal and sync is being received from a remote E3Switch converter. Refer to the front
panel section of this document for other light colors.
If orange, data will not be received by the local converter and the loss of data is occurring on the link
between the converters. Check that the incoming circuit ID shown at the top of the converter's HTTP
management page matches the circuit ID being transmitted by the remote converter as shown at the
remote converter's HTTP management settings page (only applies if framing is C-Bit DS3 and
firmware since November 2009 exists in units at each end of the link).
If flashing orange/green, the link may be in loopback as indicated by the HTTP management status
page.
3. If the ISP indicates it is not receiving a valid DS3 from the E3Switch unit, check the TX path starting at
the local unit. Ensure the carrier believes the link is set up in unchannelized mode (not subdivided into
T1 or E1 channels). Either M13 or C-Bit framing is fine but the configuration page setting of each
converter should match and the carrier should have consistent framing settings on intermediate
equipment – not mixed among M13 and C-Bit or autoconfigure.
If flashing orange/black, the link is in a configured return-to-service delay mode as discussed
elsewhere.
4. CRC-length, scrambling, subrate/fractional settings must be consistent between the E3Switch and the
ISP. Inconsistent settings will not show up as DS3 line errors at the HTTP status screen of the
converter, but may show up as CRC, or length packet errors at the status screen, and may result in an
apparently successful PPPoE session initiation being terminated shortly thereafter when PPP logon or
IP address negotiation fails between the PPPoE user-equipment and the ISP.
5. The user-name and password for your PPPoE are provided by the ISP and are not relevant to the
converter; however the session-name for the PPPoE connection must be blank or empty.
The HTTP status screen of the converter will indicate whether the PPPoE connection is active or
unconnected. PPPoE packet exchange is indicated in the log found at the bottom of the HTTP settings
screen. If the packet exchange appears valid but the link is terminated shortly thereafter, ensure that
your PPPoE equipment's setting for username, password and IP address (fixed vs. DHCP) are correct.
All can terminate a PPPoE session shortly after initiation. A valid PPPoE connection handshake
appears as follows:
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