How to configure 2 cellular interfaces as Primary & Backup links to connect to the internet

Publication Date:  2016-08-29 Views:  790 Downloads:  0
Issue Description

Customer has an AR169FGWL router with firmware version V200R005C32SPC200 and he is trying to configure interfaces cellular 0/0/0 and 0/0/1 with PPP authentication.
He wants to use them as two links for internet connection.


On the cellular interface 0/0/1 he successfully activated PPP authentication mode:


#
interface Cellular0/0/1
link-protocol ppp
ip address ppp-negotiate
dialer enable-circular
dialer-group 1
dialer timer idle 3600
dialer timer autodial 10
dialer number *99# autodial
qos lr pct 2
nat outbound 3900
zone untrust
#


On the cellular interface 0/0/0 for some reason the activation doesn't work:
[TPGTPG-S1-ELI-AR169FGWL-AR-01-Cellular0/0/0]link-protocol ppp
Info: This Cellular interface does not support PPP protocol.
[TPGTPG-S1-ELI-AR169FGWL-AR-01-Cellular0/0/0]dis this
#
interface Cellular0/0/0
timer hold 20
ip address ppp-negotiate
dialer enable-circular
dialer-group 1
dialer timer idle 3600
dialer timer autodial 10
dialer number *99# autodial
qos lr pct 2
nat outbound 3900
zone untrust
#


The customers is asking for a solution in case the router capabilities fulfill his needs. Customer didn't encountered this issue on AR1220.

Moreover, customer claims that on interface cellular 0/0/1 cannot be performed sim switch:
[TPGTPG-S1-ELI-AR169FGWL-AR-01-Cellular0/0/1]sim switch to 1
Info: The interface does not support switch sim card.

 

Handling Process
Considering all the informations provided by the customer and the fact that he said he could easily perform this configuration on AR1220, it was obviously to notice the big difference between AR169FGWL and AR1220 regarding cellular interfaces.
In the following points is the explanation for the behaviour of the interfaces:

1. On the AR169FGWL there is only one 3G USB modem port (1- in the picture below) and two SIM slots, which work as main/backup, so they can be considered as one (15- in the picture below). 


2. Cellular interface 0/0/0 is used for the two SIM slots and it can be performed SIM switch, meanwhile the 0/0/1 is used for the external USB 3G modem. Having only one SIM you cannot do SIM switch on 0/0/1.

3. On the other hand, on cellular interface 0/0/0 PPP cannot be used because it is an LTE modem (ME906E). It uses DHCP to get IP address. All interfaces except Ethernet and LTE cellular interfaces run PPP at the link layer.
[TPGTPG-S1-ELI-AR169FGWL-AR-01-Cellular0/0/0]dis cel 0/0/0 all
Modem State:
Hardware Information.
=====================
Model = ME906E
Modem Firmware Version =  11.234.46.02.00
Hardware Version = MD1ME906EM
Integrate circuit card identity (ICCID) = 8961025716404556208
International Mobile Subscriber Identity (IMSI) = 505025700416879
International Mobile Equipment Identity (IMEI) = 866714010654597
Factory Serial Number (FSN) = E2HBY15605009513
Modem Status = Online

 

Solution

Unlike on AR1220 were there are available two 3G USB Modem ports, on AR169FGWL we have only one 3G USB Modem port and an internal SIM slot.
The following workaround should be applied for an internet connection on both cellular interfaces:


1. Cellular interface 0/0/0 (internal slot) uses DHCP to get IP address. So is necessary to input under it the command ip-address negotiate
[TPGTPG-S1-ELI-AR169FGWL-AR-01-Cellular0/0/0]ip address negotiate
#
interface Cellular0/0/0
dialer enable-circular
dialer-group 1
apn-profile lteprofile
dialer number *99# autodial
qos lr pct 2
nat outbound 3900
zone untrust
ip address negotiate
#


2. Cellular interface 0/0/1 (3G USB Modem). Here the customer must have an 3G modem where he can insert the SIM card and use this configuration as an example:
#
interface Cellular0/0/1
link-protocol ppp
ip address ppp-negotiate

dialer enable-circular
dialer-group 1
dialer timer idle 3600
dialer timer autodial 10
dialer number *99# autodial
qos lr pct 2
nat outbound 3900
zone untrust
#

END