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Cisco Meraki Documentation

APN Selection

APN Selection

To initiate a data session with the cellular network, the device (MG) requires the configuration of an Access Point Name (APN). There are three distinct methods through which an APN can be configured on the modem:

 

  1. APNs Loaded by Modem Firmware:

Some modem vendors provide specific modem firmwares tailored to major Service Providers (SPs) such as Verizon, AT&T etc. During the boot-up process, when the modem detects the SIM card and identifies the carrier associated with it, it loads the corresponding modem firmware required by that carrier. The firmwares linked to major SPs include a repository of APNs specific to those carriers. 

For instance, the Verizon firmware loads the 'vzwinternet' APN, while the AT&T firmware loads 'broadband'. By default, the host platform should utilize these APNs to establish the data session when operating on the networks of these specific service providers. This ensures seamless compatibility and optimal performance in alignment with the carriers' network configurations.

 

  1. Program manual APN by User:

Some customers like to use custom created APN’s.  This usually happens when they want to use a custom APN other than the generic APN associated with a carrier.  This could be to restrict inbound access to devices behind a firewall with a virtual Private network (VPN) and route traffic through VPN tunnel, or to create a second layer of data encryption.  User can configure this APN via dashboard or LSP. 

  • Via Dashboard

Click on the Uplink Tab of the MG and scroll down to Configuration.  Click on the edit button as shown below

sim_card.png

 

edit_sim.png

    The fields to be filled are explained below

  • Name - This field is to enter the APN provided by the carrier

  • IP type - The user can specify the preferred IP type for the devices connecting through that APN.  The different IP types are IPv4, IPv6 and IPv4v6.

  • Authentication - This field is used to specify the authentication method for the MG to establish a successful connection.  The different types of authentication are PAP(Password Authentication Protocol), CHAP(Challenge Handshake Authentication Protocol) and None.

  • Username - This field is used to specify the associated username

  • Password -  This field is used to specify the associated password

Note : If incorrect information is entered for any or all of the parameters mentioned above, it will prevent the establishment of a data session over the cellular network, thereby causing the MG to remain offline.


 

  • Via LSP

 

Once you open the LSP of the MG, click on the “Configure” Tab.  Under Cellular Settings check mark the “Override SIM1 data session setting” ( if active sim is SIM1) or else “Override SIM2 data session setting “ ( if active sim is SIM2)

Enter the APN Name , IP type and Authentication if any.

LSP_cellular.png

 

The fields to be filled are explained below

  • APN Name - This field is to enter the APN provided by the carrier

  • IP type - The user can specify the preferred IP type for the devices connecting through that APN.  The different IP types are IPv4, IPv6 and IPv4v6.

  • Authentication - This field is used to specify the authentication method for the MG to establish a successful connection.  The different types of authentication are PAP(Password Authentication Protocol), CHAP(Challenge Handshake Authentication Protocol) and None.

  • Username - This field is used to specify the associated username

  • Password -  This field is used to specify the associated password


 

  1. APN’s created by AutoAPN Process:

With the exception of a few major Service Providers (SPs), the majority of other SPs lack a dedicated modem firmware for their network. In instances where the modem identifies a SIM card from these service providers, it loads a generic firmware to facilitate compatibility and connectivity. Generic firmwares do not have any default APN’s in its repository.  This is when the “ AutoAPN Management Process” will create a data APN based on a certain algorithm.


 

 Common FAQ’s regarding APN:

 

How does the MG determine which APN to use?

The MG behavior by default, when you first power it on, will be to scan the SIM card, determine which carrier APN it could be, and then initiate a connection. The APN assumed is fetched from a combination of SIM card and operator MCC (Mobile Country Code) and MNC (Mobile Network Code). From this combination, it selects that APN from the firmware APN list as mentioned in point 1.

Depending on the user’s order of operations, the MG may attempt the first connection using an APN from the internal list we built. If the user powers it on and does not enable override settings for the APN, we should expect it to use a match against an existing entry in the APN list. This behavior tackles the problem of manually entering in dynamic IP APNs and allows for quick deployment. Users can then insert SIMs into the unit (when powered down) and ship it off to their site after testing for connectivity.

Subscribers who opt for a static IP APN, often referred to as a private APN, usually need to manually adjust the settings on the Local Status Page (LSP). Most carriers do not permit the use of both a private APN and a dynamic APN concurrently for their service plans. Consequently, users must configure the appropriate bearer parameters, including the APN and username/password, to ensure connectivity as explained in point 2 Failure to adhere to these bearer requirements may result in the device being unable to access the internet, particularly if an incorrect APN string is entered.

 

Will the MG test connectivity from the APN list and the override?

No, once the override settings are configured in the local status page, the MG will only use the override configurations. There is no logic in the firmware at this time to try a fallback if the LSP configurations are incorrectly inputted by the user. We recommended users to test and validate configurations by checking for connectivity after setting overrides.

 

Where is this APN list located in the firmware? 

The full APN list in the firmware can be found in /usr/lib/iccid.json and /usr/lib/operator-id.json. These files can be cat’d via the web console and shows the entire list of known carriers with their ‘public’ APNs. Since the MG detects the APN through matching on the MNC and MCC, basically the ICCID, the values you see in the JSON file are used to automatically match to the existing values in the APN.

 

Why are private APNs not on the list? 

With some familiarity with the questions above regarding APNs, since we detect based on MNC/MCC, we would match on known public APNs. Private APNs are ‘private’ and thus are a special override value that should be unknown to the general public. The logic also would be unable to tell when a SIM requires a private APN. The ICCIDs of the SIM cards are the same for both private APNs and public APNs.



 

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