The Volpe Firm, Inc.

Advanced Troubleshooting in a • DOCSIS 3.0 Plant • Brady Volpe Walter Miller The Volpe Firm, Inc. JDSU

Advanced Field Troubleshooting • Why is DOCSIS 3 Troubleshooting Different? • Multiple Bonded Channels • Downstream • Not that different. • The channels are constant carrier • Multiple downstream channels have been around forever • Upstream • Still most vulnerable portion of plant • The modem is no longer limited to a single upstream transmit path • In some ways this is actually easier with DOCSIS 3.0

Partial Service • One or more upstream or downstream channels become unusable • Partial service does not necessarily impact subscriber • Can be viewed as an advantage from a network operations POV • Hard to detect after CM registration • If the channel is down when the modem registers: • Will not cause performance issues, unless US is at maximum utilization • The errors for the “down” channel(s) are reported to the CMTS in the REG-ACK • D3.0 test equipment will show fewer channels bonded that expected • If the channel is down after the modem registers: • Data loss until CMTS realizes that Ch is unusable (~1 min – 15xT3 timeouts) • T4 Timeout > CMTS stops granting transmit opportunities • CMTS vendors handle re-acquisition differently (it is a SHOULD requirement)

Impaired Service • One or more channels are experiencing RF channel impairments • Presence of codeword errors is one way to identify an impaired channel • Channel impaired when ranging ok, but data becomes corrupted • What would we say about impaired service: • Impaired service impacts subscriber performance and quality of experience (QoE) • It is easy to detect impaired service • Throughput can be a good test for this, but not in all cases • High volume Packetloss is the most effective test to detect impaired service • Customer complaints likely to generate a ticket: • VoIP issues (robo-voice, dropped words, dialing issues, dropped calls, etc.) • VOD – cannot retrieve movie, cannot interact with Guide • Gaming issues – latency, interactivity issues • VPN issues – calling, two-way video, desktop sharing, VPN dropping, etc. • File Sharing/Transfer/FTP Upstream – very slow upstream transfers

Advanced Field Troubleshooting • Evaluating the Downstream Quality • Use traditional PHY attributes • MER • BER • DQI • Use traditional Service Layer attributes • PacketLoss • Throughput

Advanced Field Troubleshooting • Evaluating the Upstream Quality • To troubleshoot the field, • look in the headend!

Partial Service Troubleshooting • Partial Service manifests as missing channels. • Does not demonstrate Packetloss or Throughput

Impaired Service Troubleshooting • An impaired service may or may not exhibit codeword errors and packetloss • When troubleshooting impaired service, it is critical to view the performance of the individual upstream channels.

Impaired Service Troubleshooting

Impaired Service Troubleshooting • Obviously there is an issue with the channel at 19 MHz • Utilize this method to traverse the network and find the impairment causing this issue

Summary • Partial Service • Tremendous Operational Advantage • Can go unnoticed • Impaired Service • Can be difficult to troubleshoot without the right tools • Many Impairments not detectable with • Packetloss • Throughput • Best Practice • Utilize tools that allow the simultaneous testing of bonded upstream channels at a PHY layer

Q&A

The Volpe Firm, Inc.