3G Theory

Today I would like to discuss about 3G theory part and would like to correlate with data communication and connectivity options for Routers.

3G is third generation in mobile communication standards. Right now 3G is in launching phase in India. 3G is as comparatively superb than 2G. 3G, everybody knows we will get more downloading speed and fast access to internet.

What is use for 3G ? What a normal person can get benefit ? The simple answers everybody know are –

Video calling , watching youtube on phone,  good speed for downloading and using apps on phone..

Here you are.. When you are watching youtube on your phone, that means you are access internet at good speed. That means I can say, I can connect  my phone to my pc using nokia pc suite or any other software and access internet. Yes we can access internet using phone  as connectivity option with our laptop/PC.

                Here the idea comes in for one more connectivity option for ISP, Right now many of service provider are planning 3G as connectivity option and majorly , those ISP who have good coverage in metro cities are deployed  this as backup connectivity option for current customer to provide good SLAs.

I think , now it’s more clear that we can use 3G as media , it can anything USB or Simcard for connectivity.  As vendors saw this as new growing market, everybody came out with 3G products like SOHO routers, CPE routers, etc.

                These routers are compatible for 3G as connectivity option. In my previous post, I explained about 3G configurations. But I think I was suppose to write this theory part first , to make everyone understand about 3G configurations. It just a dialup media , same as you connect a USB to your laptop and dial it to ISP cloud and you get a IP and surf internet.Same process for router, Router also Dial first and get IP and access internet. Routers helps to share internet to local LAN users and can enable standard function using 3G as connectivity option.  

I can say, Now a days Router uses 3G as connectivity option like SIM card or USB to provide high speed internet connectivity for multiple
users over the 3G mobile phone networks. The widespread availability
of 3G networks and the reduced cost of mobile broadband has led to a revolution in the way that businesses and consumers connect to the internet. Many of ISP are using this as 3G as backup for MPLS customer also. Here using cellular media concern customer connect to ISP cloud in respective vrf and it can access other sites. ( we will discuss this in later posts)

Router uses a single 3G SIM card or USB and provides wired and wireless Wi-Fi connectivity as well as providing additional services such as IPsec VPN and VOIP over 3G network.One case study I already shared.

Some important facts –

3G has many flavours , WCDMA and CDMA 2000 is majorly used.

CDMA 2000 includes - 1xRTT-only, EVDO-only and hybrid.

WCDMA – its majorly gsm media.

Before doing configuration confirm the flavour, Then it will be easy to configure in routers. Since both has bit configuration difference. You can check in configurations examples –

I can brief you –

• WCDMA needs correct APN name, majorly no need of username and password. Authentication happens based on APN.
• CDMA2000 needs username and password must for authentication.

Here I want share some important information about 3 G interfaces  and its communication process, –

             

             The 3G interface consists of an external modem  that you plug into the router. The card provides two logical components from a routers point of view.First, there is a control channel used by the router to talk to the modem for device setup and call control. It appears as line x in IOS. You use a chat script and AT commands to talk to the modem.

           Second, there is the data interface, Cellular X. After a connection has been established, all IP-related information and data flow goes via this interface. Its is designed like a dial on demand interface (BrI, for example), so you can put dial related stuff directly there, or use a Dialer interface that gets bound to the Cellular interface. The latter provides the advantage of an always-on setup through dialer persistent.

            The modem itself acts as a ppp server to the router (there is no PPP between the modem and the 3G cloud). It attaches via a profile to the ISP, and the APN of the ISP assigns you the information required for Internet access. The router will talk to the modem via ppp and the modem supplies the information received from the ISP (IP address, gateway, name servers etc.).

You can check coverage with sh cellular 0 all

This explanation is about 3G connectivity process.  

I hope this post will help for beginners, who are new to 3G and want to setup 3G as connectivity option in Router.  Respective configuration examples are already posted in 3G label.

For any query and feedback, Plz comment using your Name and mail id.. for easy way use Name/URL option.. 

WCDMA Installation

Hi In this section, I want to focus on 3G - WCDMA deployments. In  these days I tested many WCDMA connectivity options using mobile sim cards. I want to share some important things which will be helpful for any engineer for WCDMA installations. 

Important things to remember in WCDMA configuration –

In WCDMA we need to configure proper APN name for connectivity.

You can check apn from – show cellular 0 all

I would like to explain you full process of testing -

Check the router and other components received with router for WCDMA testing.I will give example for Maipu 1800-22-AC router. I used that one for testing.You will get external module – RM2 – 3G- GSM. In which you can insert simcard.Then insert that module in 3/0 slot of Router.  Power on router , you can see the after booting …

It will show you like below -

 Cellular 3/0 is loading,please wait...

 %LINEPROTO-5-UPDOWN: Line protocol on Interface cellular3/0, changed state to up

 Cellular 3/0 Load OK

 %LINK-5-UPDOWN: Interface cellular3/0, changed state to up

Then you can see one cellular interface in router…

Then you can do below configuration to connect internet –

First configure APN name –

You need to configure this command in privilege mode

Router#cellular 3/0 wcdma apnconfig xxxxxx (eg.- airtelgprs)

Then do below configuration -

Router#

Router#conf t

Router(config)# ip access-list standard 1

permit any

exit

Router(config)# dialer-list 1 protocol ip permit

Router(config)# chat-script g3dia ATDT

Router(config)# int celluar 3/0

interface cellular3/0

 encapsulation ppp

 ppp chap password ^QVW

 ## you can configure any password like 123,no need to wait for any password from ISP###

 ppp ipcp dns request

 ip address negotiated

 bandwidth 384

 dialer in-band

 dialer idle-timeout 0

 dialer-group 1

 dialer string *99#

 script dialer g3dia

ui-control inaccessible telnet http

 exit

Router(config)# ip route 0.0.0.0 0.0.0.0 cell 3/0

Then for testing, you can ping 4.2.2.2 , it is global dns IP. Easy to remember 

As you will get ping response. Check cellular interface it will get some ip address from ISP. Since this is a dialup connection. As you will send request to LAC , it will forward to LNS and LNS will authenticate you using APN name. So apn name is important.

In this testing troubleshooting is very important part – As it is dialup connection, Need to know where exactly is problem. I think many of you remember ISDN installations. Many times we need to do debug to find exact issue.

Here also its same. But in this case it will be easy. Since we all know PPP well. Before doing ping again, you have to do shutdown and no shutdown under cellular interface.

Then under privilege mode

Router# debug ppp negotiation

Router# debug ppp packets cellular

### Make sure that your terminal monitor is enable or you are using console. ###

Then ping again 

Router# ping 4.2.2.2 

You can see some logs.

Check the process which is the wrong

PPP negotiation process is easy for you.

LCP-- authentication-- IPCP

Be careful about magic number , compare the sent and received magic numbers, It should be same and authentication is right or wrong.Then the very important is at least should be got local IP address with 32 bit network mask.

              And most of all ISP for the WCDMA not require the username and password . but why we need configure it ? Because they need the authentication process. So any password is ok like 123. To check the sim card is which type of the 3G technology, only confirm with ISP. Or check the brand on the USB .

For more detailed information about simcard  signal strength – you can check

Show cellular 0 all

In that you can check RSSI under radio information. The range of signal is from -11 dbm to -135 dbm.(-11 is best and -135 is worst).

Now I hope you are very clear with this WCDMA process. 

I done above configuration, Here are result outputs-

Before Pinging

router#sh ip int brief

Interface                   IP-Address      Status                Protocol Description

fastethernet0               unassigned      down                  down   

fastethernet1               unassigned      down                  down   

vlan1                       192.168.1.1       down                  down   

cellular3/0                 unassigned          up                      up     

null0                         unassigned          up                      up     

Pinging

router#ping 4.2.2.2

Press key (ctrl + shift + 6) interrupt it.

Sending 5, 76-byte ICMP Echos to 4.2.2.2 , timeout is 2 seconds:

!!!!!

Success rate is 100% (5/5). Round-trip min/avg/max = 283/303/366 ms.

router#

show cellular 0 all Output

router#sh cellular 3/0 all

Hardware Information

====================

Modem device name = EM770W

Modem manufacturer = huawei

Modem Firmware Version = 531.11.00.14.113

Hardware Version = MD32TCPU

International Mobile Subscriber Identity (IMSI) = 405801170048287

International Mobile Equipment Identity (IMEI) = 357030021728958

Modem Status = online(full functionality)

Profile Information

====================

Profile 1 = ACTIVE

--------

PDP Type = IP, Header Compression = OFF Data Compression = OFF

PDP address = 0.0.0.0

Access Point Name (APN) = xxxxxxgprs

Network Information

====================

Current Service Status = Normal, Service Error = None

Current Service = Combined

Packet Service = WCDMA(Attached)

Packet Session Status = active

Current Roaming Status = Home

Network Selection Mode = Manual

Location Area Code (LAC) = 196676

Cell ID = 65690823

Registered PLMN = , Abbreviated = , numeric  = 405801

Radio Information

====================

Current RSSI = -93dBm

Security Information

===================

Card Holder Verification (PIN) Disabled

SIM Status = OK

SIM Protection = Disabled

SIM User Operation Required = None

Number of Retries remaining = 3

router#

Extended ping 

router#ping

Protocol [ip]:

Target IP address or hostname: 4.2.2.2

Repeat count [5]: 500

Datagram size [76]:

Timeout in seconds [2]:

Extended commands [no]:

Sweep range of sizes [no]:

Press key (ctrl + shift + 6) interrupt it.

Sending 500, 76-byte ICMP Echos to 4.2.2.2 , timeout is 2 seconds:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!

Success rate is 100% (500/500). Round-trip min/avg/max = 249/286/1883 ms.

After pinging –  you can see now we got IP from ISP by ppp negotiation process.

router#sh ip int brief

Interface                   IP-Address      Status                Protocol Description

fastethernet0               unassigned      down                  down   

fastethernet1               unassigned      down                  down   

vlan1                         192.168.1.1     down                  down   

cellular3/0                 59.137.26.203   up                    up     

null0                            unassigned      up                    up     

router#

For internet sharing, we can configure NAT and share internet to local users. This I already explained in previous 3G post – http://startnetworks.blogspot.com/2011/04/maipu-1800-case-study-for.html

In previous  3G posts I shared CDMA2000 configuration details, But not much focused on WCDMA. This time I tried my best to explain you about WCDMA.

  

Hope this post will be helpful for you.

For any feedback and queries, Plz comment with your name and Mail Id. You can use Name/URL option for same.