Cable Modem Error Correction
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Inc. OverviewBlogDOCSIS Basics TutorialDOCSIS 3.0 Tutorial SeriesServicesDOCSIS CMTS Expert Support and ServicePNMDOCSIS Security & Capacity PlanningOn Site System AuditRemote System AuditProduct DevelopmentBroadband ImplementationMATLAB Design ServicesMATLAB DOCSIS Bonded uncorrectable codewords cable modem Upstream Impairment SimulationSeminarsEPONSIP Trunking and VoIPWhite PapersDigital Library DOCSIS Codeword Errors codeword error rate definition | What you should know Post 108 of 186‹‹›› 09/17/2012Brady VolpeTroubleshooting DOCSIS12 comments Calculating... Calculating... DOCSIS Codeword cable modem correctables uncorrectables Errors - You will likely see them DOCSIS correctable codeword errors and uncorrectable codeword errors are available as a metric in most cable operator monitoring tools and
Fec Errors Causes
Operations Support Systems (OSS). The monitoring tools and OSS generally provide data and dashboards for users to monitor overall network health and then identify a problem when it occurs. Metrics like codeword errors are extracted directly from DOCSIS CMTSs using Simple Network Management Protocol (SNMP) or Internet Protocol Detail Records (IPDR), the later being upstream fec errors preferred due to its reduced CMTS CPU utilization. What many people struggle with are what are those codeword errors, what do they mean, and how bad is bad? This artical will answer those questions and discuss Reed Solomon forward error correction including how it corrects bit errors in the DOCSIS network. Where Codeword Errors Come From When someone is using a device, such a PC or iPad, and transmits data over a DOCSIS cable modem that larger than 16 bytes of data, an error protection algorithm kicks in called Reed-Solomon (RS) forward error correction (FEC). There are two parts to RS FEC, one is the encoder, which is in the cable modem and the second is the decoder, which is in the CMTS. As an example, the RS encoder creates an 18 byte codeword from an original 16 bytes of data transmitted by you, the user. The two extra bytes of data are added for error correction. The 16 bytes of
My Cisco Radio Frequency (RF) Hybrid Fiber-Coaxial (HFC) Upstream FEC Errors and SNR as Ways ccer cable to Ensure Data Quality and Throughput Hierarchical Navigation HOME SUPPORT TECHNOLOGY
Upstream Cer
SUPPORT BROADBAND CABLE RADIO FREQUENCY (RF) HYBRID FIBER-COAXIAL (HFC) TECHNOLOGY INFORMATION TECHNOLOGY WHITE PAPER Upstream FEC Errors
Unerrored Codewords
and SNR as Ways to Ensure Data Quality and Throughput Contents Introduction Signal-to-Noise Ratio How to Obtain SNR and CNR Readings How to View the Noise Floor http://volpefirm.com/docsis-codeword-errors/ Upstream Carriers in Zero-Span Forward Error Correction How to Obtain FEC Counters through SNMP Per-Modem FEC Counters Upstream Packet Counters Conclusion Appendix Upstream Correctable FEC Percentage Upstream Uncorrectable FEC Percentage Upstream SNR Example of How to Pull OIDs for Per-Modem FEC Counters on an MC28U or 5x20 Linecard Related Information Introduction To operate a http://www.cisco.com/c/en/us/support/docs/broadband-cable/radio-frequency-rf-hybrid-fiber-coaxial-hfc/49780-return-path-monitor.html high speed data (HSD) network over a hybrid fiber/coaxial (HFC) cable plant requires a significant level of quality control to ensure data integrity and the highest level of data throughput. The two generally accepted means by which cable operators can measure data quality is by monitoring either the bit error rate (BER) or the packet error rate (PER). The Data Over Cable Service Interface Specification (DOCSIS) outlines requirements that each cable operator must maintain in order to reliably transport IP data traffic. An important feature of DOCSIS addresses the need to protect IP data against radio frequency (RF) noise impairments. The feature DOCSIS uses to help maintain IP data integrity over HFC cable plants is Reed-Solomon Forward Error Correction (FEC) encoding. Essentially, FEC encoding protects IP data and DOCSIS Management messages against symbol errors caused by noise and other impairments. The unique feature of FEC is that it can detect symbol errors and also correct them. Thus, DOCSIS specifies that all IP
IP isWhoisCalculatorTool PointsNewsNews tip?ForumsAll ForumsHot TopicsGalleryInfoHardwareAll FAQsSite FAQDSL FAQCable TechAboutcontactabout uscommunityISP FAQAdd ISPISP Ind. ForumsJoin Search similar:[Cable] Erratic speeds with upgrade to 45/4 on Bloor POIAlready posted in the direct forum but what can u tell me?[Cable] Cable modem and version autorised[Signals] correctables,uncorrectables[IA] Modem Reboots[Speed Issues] Has anyone else had http://www.dslreports.com/forum/r26626606-Signals-Uncorrectable-codewords-too-high this problem with 60 Mbps upgrade?? Forums → US ISPs cable → Comcast XFINITY → [Signals] Uncorrectable codewords too high? uniqs18483 Share « [Connectivity] Homestead Florida outage??? • [Signals] Which attenuator to buy?? » dorkinoPremium Memberjoin:2004-02-22Atlanta, GA1 edit dorkino Premium Member 2011-Dec-6 3:54 pm [Signals] Uncorrectable codewords too high?CM SignalsI was looking over another post when I noticed someone mentioned that the total # of uncorrectable cable modem codewords should never exceed the # of correctable. Is this true? If so, do I have a significant problem with my connection? Other than the occasional slowness or lag in a game, I haven't noticed too much in the way of problems. Sometimes it seems some sites are slower than others, but I just attribute that to the load on their servers at the time or just cable modem error the general state of the connections between me and them.Curious what you guys think. Thanks.BTW, I have a Motorola SB 6120 running SB612X-1.0.3.3-SCM00-NOSH firmware w/ Comcast Blast 20Mbps service. The modem has been online for 11 days. · actions · 2011-Dec-6 3:54 pm · andyrossMVMjoin:2003-05-04Schaumburg, ILkudos:2 andyross MVM 2011-Dec-6 3:59 pm How long have your modem been up? The 6120 tends to log 1000-2000 errors during it's initial connection. What's most important is to keep an eye on it and see how often and fast it increases. Mine tends to be fairly constant once booted, but may jump up, usually accompanied by a T3 or other error in the log. It's not very often.On the other hand, ever since they changed to 8 channels here, the correctable codewords increases constantly, even though signal levels and SNR are the same as before. · actions · 2011-Dec-6 3:59 pm · ctgreybeardOld dogs can learn new tricksPremium Memberjoin:2001-11-13Bethel, CTARRIS SB6183Asus RT-AC66 ctgreybeard to dorkino Premium Member 2011-Dec-6 4:00 pm to dorkinoI don't think you have a problem. In my experience there are a thousand or so uncorrectables that occur immediately after modem startup. I think that's what you see t
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