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Cisco Bug: CSCuo54863 - Cable Modems online but unpingable, no IP address assigned to CPE

Last Modified

Jan 28, 2017

Products (1)

  • Cisco uBR10000 Series Universal Broadband Routers

Known Affected Releases


Description (partial)

1.After clear cable modem all delete, mass modem re-registration may result in modem(s) dropped into the CMTS Filter Group 255 due to missed IPC communication between RP and CLC.

One can detect this by "show cable modem access-group | inc 255"

If modem in the list is online(pt) and "show cable modem xxxx priv verbose" looks correct, this the issue. If modem is in any other state (e.g. reject(pk), *online, etc) this is expected and not a hit.

2.For multicast/DSG issue: Multicast / DSG use the same message queque to create service flow, so if IPC communication missed,  the Multicast/DSG service flow will be failed.  can be detect by "show interface XXX multicast-gcr" the SFID is 0.

1.This appears to happen in SCH2 and PRE4.  PRE5s properly are also affected.

Clear cable modem all delete or any mass-reregistration that results in high IPC flow may trigger this.

Normal reload and reboot of CMTS is less likely to hit this issue as modems already hit their timeout for re-ranging and the random backoff timers result in more uniform modem registration requests rather than a flood of requests resulting from a all modem clear command.

2.For multicast/DSG issue: appears to happen in SCH2 and PRE4.  PRE5s properly are also affected. If there are lots of static multicast /DSG configured and CM count is huge, the issue mostly happened during reload.
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