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Wednesday, October 23, 2013

4G HWIC Roaming After Inactivity

We are using the 4G HWIC in the cisco 2900 ISR routers for backup WAN connectivity via VPN tunnel. We have built EEM scripts that enable the cellular interface when the primary ISP (interface) fails.

working cellular status......

Radio Information
=================
Radio power mode = ON
Current RSSI = -64 dBm
LTE Technology Preference = LTE
LTE Technology Selected = LTE


After around 7-10 days the cellular card startsto roam as if the card is hibernating.

Radio Information
=================
Radio power mode = ON
Current RSSI = -125 dBm
LTE Technology Preference = LTE
LTE Technology Selected = LTE


The only way to fix the problem so far that I found is to power cycle the router. This will not work as a solution. we have tried shutting down the cellular interface but that does not work and you can not reset the radio from the IOS commads. we called Verizon to see if the 4G network was blocking me due to inactivty and they pointed to the cellular card as the problem.

This is a bug with the modem firmware that runs onthe HWIC itself. Luckily new firmware has been released which you must get from Cisco. Once you load the firmware in flash, the command is- microcode reload cellular 0 0 modem-provision flash:MC7750_VZW_03.05.10.06_00.cwe  (assuming your HWIC is in slot 0)


After you upgrade the modem to the new firmware you can get rid of all those EEM scripts. It should run great after this upgrade. We had the exact same problem you have and it fixed issues with a number of sites. The modem will power cycle after the upgrade so you will loose connectivity but if the upgrade is successful the connection should nail back up after the power cycle. This problem has plagued us since day one of these LTE HWICs. The minimum IOS to support the new modem firmware is 15.2(4)M3. Make sure you upgrade the IOS first, then the modem.

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