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Table Of Contents
Release Notes for Linksys WCM300
Cable Modem SoftwareResolved Caveats in Version 1.5
Resolved Caveats in Version 1.4
Resolved Caveats in Version 1.3
Resolved Caveats in Version 1.2
Resolved Caveats in Version 1.1
Obtaining Documentation and Submitting a Service Request
Release Notes for Linksys WCM300
Cable Modem Software
Revised: April 9th, 2009, OL-14624-04These release notes describe information about support for the Linksys WCM300 cable modem software, up to and including Version 1.5.
Contents
This release notes contains the following sections:
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Obtaining Documentation and Submitting a Service Request
Introduction
The Linksys WCM300-NA (for DOCSIS) and WCM300-JP (for J-DOCSIS) wideband cable modems support the acquisition of up to three wideband (bonded) channels:
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For each wideband channel, the Linksys WCM300 wideband cable modem supports the reception of one or more bonded Radio Frequency (RF) channels. The Linksys WCM300 software supports the receiving of a 50-MHz capture window of up to eight downstream channels at 6 MHz per channel or six downstream channels at 8 MHz per channel. The total of the RF channels in the primary and secondary bonded channels must comply with the 50-MHz capture window limitation.
For wideband, the Linksys WCM300 also supports reception of one primary downstream channel (traditional DOCSIS channel from the Cisco uBR10-MC5X20 line card) for MAC management and signaling messages, and uses the associated traditional DOCSIS upstream channel for return data traffic and signaling. The upstream channel works as it does in DOCSIS 2.0 cable modems.
System Requirements
Table 1 lists the Linksys WCM300 software to which these release notes apply.
Table 1 Linksys WCM300 Software
wcm300jp-mzs.1.5.img
Signed code file for Japan
wcm300na-mzs.1.5.img
Signed code file for North American DOCSIS
For the reception of wideband (bonded) channels, the Linksys WCM300 modem requires that the cable modem termination system (CMTS) is the Cisco uBR10012 router. The Cisco uBR10012 CMTS must have certain components installed, such as the Cisco 1-Gbps Wideband shared port adapter (SPA), Cisco Wideband SPA Interface Processor (SIP), and other associated modular CMTS components. For the complete CMTS component set that is required for the reception of bonded channels on the Linksys WCM300 modem, see the Cisco Cable Wideband Solution Design and Implementation Guide, Release 1.0.
The Linksys WCM300 modem is also compatible with DOCSIS 2.0 and will operate in that mode if the modem is connected to a non-wideband Cisco CMTS or to a non-Cisco CMTS. The modem is also backward-compatible with existing DOCSIS 1.x networks. The Cisco uBR10012 router is not required as the CMTS for DOCSIS 1.x/2.0 operation.
Limitations and Restrictions
Note
Caveats
Caveats describe unexpected behavior in Cisco IOS software releases. Severity 1 caveats are the most serious caveats; severity 2 caveats are less serious. Severity 3 caveats are moderate caveats.
Open Caveats in Version 1.5
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Symptom: Setting 0x40 and disabling the HTTP access from CPE side to the modemCmHTTPAccessEnable MIB with configuration file (TLV11) disables both RF and CPE side access.
Condition: The issue was caused by the TI 3-party library.
Resolved Caveats in Version 1.5
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Symptom: Modification of the Japanese frequency scanning plan for the Linksys WCM300.
Condition: Japanese customers wanted to have an extended Incremental Related Carrier (IRC) scanning frequency plan right after original Japanese scanning frequency plan.
Workaround: The new frequency scanning plan is as follows:
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2.
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4.
Open Caveats in Version 1.4
There are no open caveats in version 1.4 for Linksys WCM300 software.
Resolved Caveats in Version 1.4
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Symptom: The Linksys WCM300 suspends normal operation when the RF signal is terminated.
Conditions: This occurs when the RF signal recovers after several seconds.
Workaround: Reboot the Linksys WCM300.
Open Caveats in Version 1.3
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Symptom: The Linksys WCM300 software is not able to initialize after a switchover and disappears.
Resolved Caveats in Version 1.3
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The Annex-A cable modem failed to acquire the RF sync signal from the bonding group.
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The HTTP (WebUI) access is not enabled in the Linksys WCM300 original design after cable modem registration.
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The original Linksyssoftware had Power, Downstream, Upstream,Online, and Link/Activity LEDs function in accordance with section 10.1 of DOCSIS 2.0 OSSI specifications. In version 1.3, Linksys software has been changed as per requirements from the customer. The new software uses the LED scheme listed in Table 2.
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The modem failed to come to w-online state. Plant condition variations might cause locking problems on the WB Downstream.
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For a physical configuration that has different fiber nodes containing separate RF channels that use the same frequency, Cooper CM randomly selects a downstream service group (DS-SG), sometimes making the wrong DS-SG selection.
Open Caveats in Version 1.2
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Symptom: The flash memory is erased when the Annex A Cooper cable modem (CM) attempts to download an Annex B image and a Code Verification Certificate (CVC) failure is seen while programming the flash. Consequently, the Cooper CM ends up with no image in that sector of flash.
Condition: This problem occurs with the Annex B Cooper CM (downloading the Annex A image) and the Annex A Cooper CM (downloading the Annex B image).
Resolved Caveats in Version 1.2
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Symptom: The Linksys WCM300 modem channel synchronization is too robust.
Workaround: A positive lock is required to avoid "false positive lock" indication.
Open Caveats in Version 1.1
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Symptom: The Linksys WCM300 fails to complete a sweeping ping of the CPE device when the CPE uses a Gigabit Ethernet interface that does not support Pause flow control.
This is a known design limitation. The upstream buffering for the Customer Premies Equipment (CPE) interface is only 8 KB. The TCP slow start mechanism ensures that data is sent at a low rate when sending from a higher speed network into a slower speed mechanism. Due to the slow upstream rates, a single TCP client can be expected to send only a single Maximum Transmission Unit (MTU) at a time. Therefore, the 8-KB buffer limit should only be exposed if six or more clients happen to be sending MTU-sized packets simultaneously. Statistically, many more than six clients would have to be sending in order to have their MTU-sized packets line up. When the 8-KB buffer limit is hit, packets will be dropped resulting in retransmission.
Workaround: Use a CPE Gigabit Ethernet interface that supports Pause flow control, or if bandwidth requirements permit, use a Fast Ethernet CPE interface instead of a Gigabit Ethernet interface.
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Symptom: When the Linksys WCM300 sees two identical secondary bonding group configurations from two different CMTS routers, it is possible that the Linksys WCM300 modem will lock on to a primary bonded channel from one CMTS and secondary bonding channels from the other CMTS.
Currently, there is no mechanism defined for the Linksys WCM300 modem to detect when a bonding group is coming from a different CMTS.
Workaround: There is no known workaround.
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Symptom: The Linksys WCM300-JP modem running the J-DOCSIS software image does not operate in the extended downstream region 70 to 88 MHz.
Workaround: There is no known workaround.
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Symptom: The ccmwbRFChannelDownPower (CISCO-CABLE-MODEM-WIDEBAND-MIB object), which reports power on wideband channels, shows power that is 10 times greater than the actual power.
Workaround: Divide the power reported by 10.
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Symptom: The SysDescr (SNMPv2-MIB object) does not report the appropriate model number/SKU for the Linksys WCM300 modem.
Workaround: There is no known workaround.
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Symptom: In the Linksys Web User Interface, the StatusLog.htm page does not reload in the Netscape browser when the Reload button is clicked.
Workaround: There is no known workaround.
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Symptom: The CMTS does not allow the Linksys WCM300 to come to the w-online state if the total number of channels provisioned for the modem in the primary and secondary bonding groups exceeds eight because channels overlap between the groups.
Workaround: Overlapping channels can be used, but the total number of channels provisioned for a WCM300 must not exceed eight.
Resolved Caveats in Version 1.1
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When ifAdminStatus (IF-MIB object) is set to the down state for one index, all indexes are shown as down.
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The ifSpeed (IF-MIB object) for the CPE interface shows 100 Mbps when actual speed is 1000 Mbps.
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The ccmwbBundleBSID (CISCO-CABLE-MODEM-WIDEBAND-MIB object) does not correctly display wideband channel IDs.
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The Linksys Web User Interface needs to be implemented on Linksys WCM300 modem.
Related Documentation
Refer to the following documents for additional information about the Linksys WCM300 modem and the Cisco Cable Wideband Solution:
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http://www.cisco.com/en/US/docs/cable/cmts/wideband/solution/guide/release_1.0/wb_solu.html
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http://www.cisco.com/en/US/docs/cable/cmts/ubr10012/roadmap/u10krdmp.html
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http://www.cisco.com/en/US/docs/cable/cmts/ubr7200/roadmap/7200rdmp.html
Obtaining Documentation and Submitting a Service Request
For information on obtaining documentation, submitting a service request, and gathering additional information, see the monthly What's New in Cisco Product Documentation, which also lists all new and revised Cisco technical documentation, at:
http://www.cisco.com/en/US/docs/general/whatsnew/whatsnew.html
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