General Packet Radio Service is a radio technology forGSM networks that adds packet-switching protocols,shorter set-up time for ISP connections, and offer thepossibility to charge by amount of data sent rather thanconnect time. GPRS promises to support flexible data transmissionrates typically up to 20 or 30 Kbps (with a theoreticalmaximum of 171.2 Kbps), as well as continuousconnection to the network. A 2.5G enhancement to GSM, GPRS is the mostsignificant step towards 3G, needing similar businessmodel, and service and network architectures.
Inefficient use of the radio interface resources. The call establishment time is too long Download takes too long. Only text SMS is supported GSM is too expensive for serving in the Internet andsometimes the user had to pay for a connection for whichhe didn’t get any data at all (data losses).
Efficient utilization of radio resources where in achannel can be shared by multiple user. User pays for the volume of data transmitted.
Packet Control Unit (PCU) Serving GPRS Support Node (SGSN): The MSC ofthe GPRS network Gateway GPRS Support Node (GGSN): Gateway toexternal networks Border Gateway (BG): Gateway to other PLMN
Intra-PLMN backbone: an IP based network inter-connecting all the GPRS elements Charging Gateway (CG) Legal Interception Gateway (LIG) Domain Name System (DNS) Firewalls: Used for security reasons wherever aconnection to an external network is required.
IP stands for Internet Protocol. It specifies the format of packets, also calleddatagrams, and the addressing scheme. IP by itself is something like the postal system. Itallows you to address a package and drop it in thesystem, but there’s no direct link between you andthe recipient.
IP when combined with a higher- level protocolcalled Transport Control Protocol (TCP) enables toestablishes a virtual connection between adestination and a source. The virtual connection so formed with thecombination of TCP and IP ( and hence TCP/IP),enables the two hosts to send messages back andforth for a period of time.
Identifies host uniquely on a TCP/IP network. Consist of 32 bits arranged in 4 octets. Can be represented in decimal notation as A.B.C.Dwhere A,B,C,D can be any decimal number between0 to 255. Overall 232 = 4295 million IP addresses IP address consist of two parts:Network Id and Host Id Subnet Mask identifies the Net Id and Host Id. Internet Assigned Number Authority (IANA) assignsIP Addresses to companies
Public IP addresses are range of IP addressesrecognised by Internet for routing data traffic. Private IP addresses are range of IP addresses usedto create separate islands of network following sameIP schema. The pool of Private IP addresses are:From 10.0.0.0 to 10.255.255.255From 172.16.0.0 to 172.31.255.255From 192.168.0.0 to 192.168.255.255
Static IP Host configuration means that the IPaddress remains with the host forever until manuallychanged. Dynamic IP Host Configuration means same ordifferent IP address allocated to the host every timeit logs on to the network.
DHCP stands for Dynamic Host ConfigurationProtocol Dynamic IP Host Configuration is done with thehelp of DHCP protocol and the server running thisservice is called DHCP Server.
Used to provide connectivity between differenthost with in a same network. The same network means the Network Id of allthe host must be same.
Used to provide connectivity between hosts whichare part of different network. Host belonging to different network are identifiedby different Net Id.
Once a packet is delivered to a host, the questionarises to which application process should thetransport layer deliver it. TCP and UDP provide an addressing method toseparate different application processes inside the IPcapable devices, and this is referred to as PortNumbers. Each application running on the IP capable device isallotted one port number. Port number runs from 0 to 65536.
A socket is simply a combination of IP address andPort number.
NAT stands for Network Address Translation. It is a way of translating a range of IP addresses todifferent range of IP address(es). Often used for saving public IP address and isimplemented in routers/ firewall connected to theexternal network.
Domain name system is an application layerprotocol which is used to convert difficult toremember 32 bit IP address to more easilyremembered symbolic names.examplewww.google.com <-> 188.8.131.52 The DNS in GPRS network helps to find the correctGGSN IP address based on the Access Point Name(APN) supplied by the MS.
A firewall is simply a program or hardware devicethat filters the information coming through theInternet connection into your private network orcomputer system. If an incoming packet ofinformation is flagged by the filters, it is notallowed through. Firewalls use one or more of three methods tocontrol traffic flowing in and out of the network:- Packet filtering- Proxy service
Packets (small chunks of data) are analysed againsta set of filters. Packets that make it through the filters are sent tothe requesting system and all others are discarded.
Information from the Internet is retrieved by thefirewall and then sent to the requesting system andvice versa.