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3G Wireless Overview
Figure 26illustrates a basic setup for 3G wireless connectivity for two branch offices. Branch Office A has a T1 leased line as the primary wide area network (WAN) link and a 3G wireless modem connection as the failover link. Branch Office B uses the 3G wireless modem connection as the primary WAN link.
Figure 26: Wireless WAN Connections for Branch Offices
Supported Devices and 3G Wireless Modem Cards
Juniper Networks supports 3G wireless modem cards that you can install into the ExpressCard slot in SRX210 devices. When used in a branch office, the SRX210 device can provide dial-out services to PC users as well as forward IP traffic onto the service provider’s cellular network.
Juniper Networks supports the following 3G wireless modem cards:
- Sierra Wireless AirCard Global System for Mobile Communications (GSM) High-Speed Downlink Packet Access (HSDPA) ExpressCard
- Sierra Wireless AirCard Code-Division Multiple Access (CDMA) 1xEvolution-Data Optimized (EV-DO) rev. A ExpressCard
GSM and CDMA are competing digital cellular phone technologies. GSM is used by AT&T, T-Mobile, and by cellular networks in countries other than the U.S., Japan, India, and Korea. CDMA is used by Sprint and Verizon.
3G Terms
Before configuring 3G wireless modems, become familiar with the terms defined in Table 60.
Table 60: 3G Terms
Term | Definition |
|---|---|
Access point name (APN) | Provides routing information for GPRS. The APN consists of two parts: the Network ID, which identifies the external service requested by a user of the GPRS service, and the Operator ID, which specifies routing information. |
AT | A set of modem commands, preceded by AT, originally developed by Hayes, Inc. for their modems. The structure (but not the specific commands, which vary greatly from manufacturer to manufacturer) is a de facto industry standard for modems. |
Base Transceiver Station (BTS) | Located at the cellular service provider network, BTS provides the radio or the Physical Layer connectivity between the mobile user and the mobile network. |
Code-Division Multiple Access (CDMA) | Multiplexing protocols used in wireless communications. CDMA is used by Sprint and Verizon cellular networks. |
Control and Status (CNS) message | These messages are used to:
|
Diagnostic Mode (DM) | Qualcomm Diagnostic Mode is the protocol specification and mechanism that is used to allow collection of debug logs from Sierra 3G wireless modem firmware. |
dial backup | Feature that reestablishes network connectivity through one or more backup dialer interfaces after a primary interface fails. When the primary interface is reestablished, the backup is disconnected. |
dialer interface | Logical interface for configuring properties for a 3G wireless modem connection. |
dialer pool | One or more physical interfaces that are associated with a dialer profile. |
dialer profile | Set of characteristics configured for the 3G wireless modem interface. Dialer profiles allow the configuration of physical interfaces to be separated from the logical configuration of dialer interfaces required for 3G wireless modem connectivity. This feature also allows physical and logical interfaces to be bound together dynamically on a per-connection basis. |
Evolution Data Optimized (EV-DO) | Standard for transmitting data through radio signals. |
Electronic Serial Number (ESN) | Number that is printed on the 3G wireless modem card itself. You can also use the show modem wireless interface firmware command to display this number. |
General Packet Radio Services (GPRS) | Packet-based wireless service used in GSM networks. |
Global System for Mobile Communications (GSM) | Standard used by AT&T and T-Mobile cellular networks. |
High Speed Downlink Packet Access (HSDPA) | 3G mobile communications protocol. |
Internet-based Over the Air (IOTA) | Activation method used by cellular network providers such as Sprint for CDMA EV-DO 3G wireless modem cards. |
Over the Air Service Provisioning (OTASP) | Activation method used by cellular network providers such as Verizon for CDMA EV-DO 3G wireless modem cards. |
Preferred Roaming List (PRL) | File that contains information for accessing the device's home network, as well as the service provider's roaming partners. |
Subscriber Identity Module (SIM) | Detachable smart card on the GSM HSDPA 3G wireless modem. |
