Repurposing a Cisco1921 for LTE networking

[fabios]

Hello everybody,

I just pulled from production an old C1921-k9 which onorably served for 14 years as main router terminating a PPPoE FTTC connection providing VPN services for a SOHO network. Now with FTTH the router has reached its limit and been upgraded to 1161-8P-X which is a ten fold throughoutput increase but the 1921 has still some life into it and I acquired a LTE card in order to have  connectivity available in a remote location.

Unfortunately I have no experience with wireless 4g networking (although I have with modems and dialers) and I did quite a bit of reading. I came up with a config which raises many doubts but doubts.

The main doubt concerns the RSSI value. While the router is in a well covered area, and I have even attached antennas, I get this:

sarlan1921#sh cell 0/1/0 all
Hardware Information
====================
Modem Firmware Version = SWI9600M_03.05.10.06ap
Modem Firmware built = 2012/11/12 15:07:45
Hardware Version = 10
Device Model ID: MC7750
Package Identifier ID: MC7750_03.05.10.06_00_vzw_033.010_000
International Mobile Subscriber Identity (IMSI) = 222101648857614
International Mobile Equipment Identity (IMEI) = 990000820188367
Integrated Circuit Card ID (ICCID) = 8939104520043236325
Mobile Subscriber Integrated Services
Digital Network-Number (MSISDN) =
Current Modem Temperature = 26 deg C
PRI SKU ID = 9900853, PRI version = 00.05

Profile Information
====================
Profile password Encryption level: 7


Profile 1 = INACTIVE* **
--------
PDP Type = IPv4
Access Point Name (APN) = mobile.vodafone.it
Authentication = None

Profile 2 = INACTIVE
--------
PDP Type = IPv4
Access Point Name (APN) = mobile.vodafone.it
Authentication = PAP
Username: none
Password: 000A1C0801

Profile 3 = INACTIVE
--------
PDP Type = IPv4
Access Point Name (APN) = cgp.vzwentp
Authentication = None

Profile 4 = INACTIVE
--------
PDP Type = IPv4v6
Access Point Name (APN) = vzwapp
Authentication = None

* - Default profile
** - LTE attach profile


Data Connection Information
===========================
Data Transmitted = 0 bytes, Received = 0 bytes
Profile 1, Packet Session Status = INACTIVE
Profile 2, Packet Session Status = INACTIVE
Profile 3, Packet Session Status = INACTIVE
Profile 4, Packet Session Status = INACTIVE
Profile 5, Packet Session Status = INACTIVE
Profile 6, Packet Session Status = INACTIVE

Network Information
===================
Current System Time = Sat Mar 27 3:17:24 2021
Current Service Status = No service
Current Service = Unknown
Current Roaming Status = Roaming
Network Selection Mode = Automatic
Network = "00014"
Mobile Country Code (MCC) = 65535
Mobile Network Code (MNC) = 65535
Packet switch domain(PS) state = Not attached
Cell ID = 0
Primary Scrambling Code = 65535

Radio Information
=================
Radio power mode = ON
Channel Number = 0
Current Band = Unknown
Current RSSI = -128 dBm
Radio Access Technology(RAT) Preference = AUTO
Radio Access Technology(RAT) Selected = AUTO

Modem Security Information
==========================
Card Holder Verification (CHV1) = Disabled
SIM Status = OK
SIM User Operation Required = None
Number of CHV1 Retries remaining = 3

GPS Information
==========================

GPS Info
-------------
GPS Feature: enabled
GPS Port Selected: Dedicated GPS port
GPS State: GPS disabled

SMS Information
===============
Incoming Message Information
----------------------------
SMS stored in modem = 0
SMS archived since booting up = 0
Total SMS deleted since booting up = 0
Storage records allocated = 25
Storage records used = 0
Number of callbacks triggered by SMS = 0
Number of successful archive since booting up = 0
Number of failed archive since booting up = 0

Outgoing Message Information
----------------------------
Total SMS sent successfully = 0
Total SMS send failure = 0
Number of outgoing SMS pending = 0
Number of successful archive since booting up = 0
Number of failed archive since booting up = 0
Last Outgoing SMS Status = SUCCESS
Copy-to-SIM Status = 0x0
Send-to-Network Status = 0x0
Report-Outgoing-Message-Number:
Reference Number = 0
Result Code = 0x0
Diag Code = 0x0 0x0 0x0 0x0 0x0

SMS Archive URL =

Error Information
=================

This command is not supported on 4G modems.


Modem Crashdump Information
===========================
Modem crashdump logging: off
sarlan1921#

As it is shown all profiles are inactive and RSSI is -128dbm.!

The following are the relevant bits of config, there is no route pointing to the cell interface, so if this should be a dial on demand interface it would see no traffic and stay down, but I would expect to see radio signal to a better value even if the dialing did not take place.

chat-script lte "" "AT!CALL" TIMEOUT 60 "OK"
!
controller Cellular 0/1
lte sim data-profile 1 attach-profile 1
lte modem link-recovery rssi onset-threshold -110
lte modem link-recovery monitor-timer 20
lte modem link-recovery wait-timer 10
lte modem link-recovery debounce-count 6
!
interface Cellular0/1/0
ip address negotiated
encapsulation slip
dialer in-band
dialer string lte
!

Am I correct in expecting to see a better signal value? Or the signal will stay at -128dbm until dialling?

Thanks for any useful pointers.

Fabio

[Flavio Miranda]

@fabios 

 Is this router in open area ? It has antennas properly attached?

-128 seems to be very bad.

[fabios]

Hello Flavio and Thanks.

Yer the router wa also moved from intended location to an open location in order to ensure was in good coverage. A small 4g/wifi router with a sim of same carrier and an iphone connect to the network with 4/5 bars.

Signal is there, I am not sure if I am doing things right .... Proper carrier selection/proper controller config ....

Thank you

Fabio

[Flavio Miranda]

Probably this is not working. 

Current Service Status = No service

This guide can be useful for you. 

Configuring 4G Wireless WAN - Cisco

[fabios]

Flavio, thanks again. That is the document I studied. I will re-read an experiment more with the config. But!

What I am wondering is if I should see indication of presence of signal no matter what (since signal is there for the carrier of the inserted SIM card) or I see no signal until the card is completely and correctly configured.

In the first situation not having a signal might mean that the WWIC card is not working/broke radio unit. In the second case that I need to keep working on the config. This effort would be futile in case of a non functioning WWIC.

Regards

Fabio

[Giuseppe Larosa]

Hello @fabios ,

the   SNR should be  far better then  -128dBm  as  noted .

is  a    SIM inserted  in the  LTE  module,  what floor   is  going  to  be  mounted? 

you   may need  coax cable to reach  the ground floor

Note:  the chat   script   and  firmware   version have to be checked  wth   mobile  LTE ISP

Hope  to  help

Giuseppe

[fabios]

Hello Giuseppe, thanks for your reply. The router has coverage other devices with internal antennas works with 4/5 bars of service. And yes there is a working SIM card in the EHWIC which communicates with the EHWIC (unlock and PIN change).

I am afraid the EHWIC card is not compatible with service in Italy .... According to:

https://www.cisco.com/c/en/us/td/docs/routers/access/interfaces/software/feature/guide/ehwic-4g-ltesw-book.html

The EHWIC-4G-LTE-V is for the North America. I am now sourcing a EHWIC-4G-LTE-G which should be globally compatible.

I will keep updating the post but I guess I learned something today (or last night since epiphany happened at 3 in the morning as it usually happens in software development and network configuration!

Have a nice weekend!

Fabio

[Giuseppe Larosa]

Hello Fabio,

thanks for your feedback

have a nice weekend you too

Best Regards

Giuseppe

[liviu.gheorghe]

@fabios , you should not forget about the two antennas required for the EHWIC-4G-LTE-G to function properly. I have a similar setup - a EHWIC-4G-LTE-G module on a Cisco 1921 - with both antennas (main and AUX) connected and the radio performance is very good:

c1900#sho cellular 0/1/0 radio
Radio power mode = online
Channel Number = 6175
Current Band = LTE
Current RSSI = -63 dBm
Current RSRP = -91 dBm
Current RSRQ = -14 dB
Current SNR = -4.3 dB
Physical Cell Id = 345
Number of nearby cells = 3
Idx PCI (Physical Cell Id)
--------------------------------
1 385
2 345
3 384
Radio Access Technology(RAT) Preference = AUTO
Radio Access Technology(RAT) Selected = LTE

The router is doing DMVPN over the cellular network and I have no issues with it.

HTH

[fabios · Accepted solution]

Good morning every one,

As I said the issue here was that the Card was intended for North America and non Europe, therefore the lack of signal was due to the fact there was no NorthAmerican frequencies coverage in Italy ... Duh! Acquired a global card now I have signal:

sarlan1921#sh cellular 0/1/0 radio
Radio power mode = ON
Channel Number = 525
Current Band = LTE
Current RSSI = -85 dBm
Current RSRP = -114 dBm
Current RSRQ = -10 dB
Current SNR = 5.0 dB
Radio Access Technology(RAT) Preference = AUTO
Radio Access Technology(RAT) Selected = LTE
sarlan1921#

An also I was able to configure it and get an IP and forward traffic:

sarlan1921#sh cellular 0/1/0 connection
Data Transmitted = 4506 bytes, Received = 4802 bytes
Profile 1, Packet Session Status = ACTIVE
IP address = 100.xxx.xxx.84
Primary DNS address = 10.133.47.246
Secondary DNS address = 10.128.28.16

So now everything is up and rnning, leaving trace here in order for others running in same issue to be able to address it. One lst thing is I get a modem mismatch warning but everything is fine and works. The router is expecting a 7710 modem (which is the one I see on the card ...) complains but it is up and running. If it works .... don't fix it

*Feb 6 17:37:42.419: %CELLWAN-4-CELLULAR_MODEM_SKU_MISMATCH: Cellular0/1/0: Mismatch detected between installed modem Unknown modem on SKU type EHWIC-4G-LTE-G. Expected modem for this SKU is MC7710
Feb 6 17:37:59.027: %CELLWAN-2-MODEM_UP: Modem in HWIC slot 0/1 is now UP

sarlan1921#sh ver
Cisco IOS Software, C1900 Software (C1900-UNIVERSALK9-M), Version 15.4(3)M2, RELEASE SOFTWARE (fc2)

Thanks for your time ...

Fabio

[Giuseppe Larosa]

Hello @fabios ,

this is good news, the modem choice is really important because North America mobile operators use different frequencies but also different modulation tecniques when compared to European standards.

Best Regards

Giuseppe