Configuring HWIC-3G-GSM

HWIC-3G-GSM is an awesome WAN interface card. With this card, the router can access internet via a cellular 3G network, its uses the same technology as accessing internet over your mobile phone. A SIM has to be inserted in the HWIC card. The card goes in a HWIC slot on an ISR router and since it is not hot-pluggable, the router has to be switched off before it is inserted. This card works only on Cisco ISR routers 1841 and above (2800/3800 Series) with HWIC slots. The number of HWIC-3G-GSM cards that can go on a router is limited to the number of HWIC slots the router has.

Typically HWIC-3G-GSM is used as a backup connection in most scenario's, mainly because it is a DDR (Dial on Demand Routing) connection. i.e., the connection is established only when traffic through the cellular inteface is present. The cellular interface goes down when there is no traffic. The Cellular card has an internal modem. First a profile has to be created which can done by entering the following command in priviledge mode

cellular 0/0/0 gsm profile create APN_Name chap username password

The APN Name and CHAP username and password will be provided by the 3G service provider. Some service providers do not use CHAP and in those cases they can be left blank. But you will still need to configure a dummy CHAP hostname and password on the cellular interface.

cellular 0/0/0 gsm profile create 7 webnet

Here webnet is the APN name and profile number is 7. To verify if the profile is active use the following command.

show cellular 0/0/0 profile

This command shows all the profile created on the cellular card modem. A "*" next to the profile shows that it the default profile. A chat-script need to be entered for the modem to initialize connection and the profile to be used also has to be mentioned.

chat-script gsm "" "ATDT*99*#7" TIMEOUT 60 "CONNECT"

Here 7 is the profile number. If the required profile is the default profile - then this can be left out (like in the below example).

What I really like about this card is that, If you have this card put on a 1841 ISR router, you can take it to any remote site where 3G network coverage exists and connect your Laptop to it and access Internet (Ofcourse, you will need power for your router). The RSSI indicator on the card shows the signal strength. A value greater than -90dBm is good enough. To verify the signal strength, do

show cellular 0/0/0 radio

If the signal strength is good, the cellular interface will get a public IP.

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Configuration

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do cellular 0/0/0 gsm profile create 1 web.isp

!

chat-script gsm "" "ATDT*99*#" TIMEOUT 60 "CONNECT"

!

interface FastEthernet0/1

ip address 172.28.16.1 255.255.255.0

ip nat inside

ip virtual-reassembly

duplex auto

speed auto

no keepalive

!

!

interface Cellular0/0/0

ip address negotiated

ip nat outside

ip virtual-reassembly

encapsulation ppp

load-interval 30

dialer in-band

dialer string gsm

dialer-group 2

async mode interactive

ppp chap hostname 123@dummy.isp

ppp chap password 123

ppp ipcp dns request

max-reserved-bandwidth 100

!

ip route 0.0.0.0 0.0.0.0 Cellular0/0/0

!

!

ip nat inside source list 1 interface Cellular0/0/0 overload

!

access-list 1 permit any

dialer-list 2 protocol ip list 1

!

line 0/0/0

exec-timeout 0 0

script dialer gsm

login

modem InOut

no exec

speed 384000

!