Chapter 8: LAN Connections and Performance
reassembly order is guaranteed (with bypass of high-CoS traffic) if configured in “bonded” mode (on
firmware beginning March 2008). For “load-balance” configuration, or on firmware shipped before March
2008, packet order is generally maintained but not guaranteed. Refer to the configuration section of this
document for further discussion.
TCP/IP and General Performance Tuning
In a TCP/IP environment, maximum performance across the E3, T3/DS3 link will be achieved by adjusting
TCP/IP communication parameters of all LAN equipment attached to the converter including equipment
attached indirectly via hubs, switches or bridges. It should be possible to achieve TCP/IP transfer rates
within 5% of the theoretical maximum of 44Mbit/s for T3/DS3 or 34 Mbit/s for E3. The most important
parameter to adjust for maximum performance is the TCP window size. A valuable TCP/IP performance
testing tool called IPERF or JPERF (graphical version) and many excellent documents for setting TCP
parameters are available online.
Dual-DS3/E3 converters will experience different throughput and latency if the “Port Bonding” parameter
is configured as “Bonded” vs “Load Balancing”. Refer to the operating modes and configuration section of
this document for more information.
Chapter 9: DS3 Packets and Link Topology
Link Bit-Errors
The converters at each end of the link will maintain synchronization with each other even at very high DS3
bit-error rates. The converter will count and drop packets with FCS/CRC and length errors.
Link Aggregation
Refer to the configuration section of this document for a thorough discussion.
Chapter 10: Troubleshooting
General
A great deal of diagnostic information is available by accessing the HTTP management interface of the
converter. Refer to the management section of this document for additional information.
The converter's
front panel lights can provide useful information
but are often under-utilized. They are
simple to read and can indicate where a data connection is being lost. It can be very helpful to learn their
meaning and monitor flashes as a packet is received at each port.
Incoming Circuit ID is shown at the top of the converter's HTTP management page for C-Bit DS3 links,
facilitating confirmation of the remote data transmitter when presented with a pair of unlabeled BNC cables.
The Ethernet networks to which the converter connects are complex and may contain thousands of devices,
each of which requires proper configuration and performance. As such, network configuration and
topology issues dominate when problems arise. When troubleshooting, solutions can be reached more
rapidly by remembering that
the most frequent cause of problems arises from improper network
configurations
.
The next most frequent source of problems can arise from the E3, T3/DS3
link configurations
or faults – in
other words, the microwave radio or fiber optic link or the interface and associated configuration settings
between such equipment and the converter. It is important that the telecom link is operating in
unchannelized mode and that the circuit provider has not mixed C-Bit with M13 or auto-detect framing
among the various intermediate pieces of equipment.
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