SIP Internet Protocol is the method of connecting voice over IP networks like the Internet itself. There are several advantages associated with SIP Internet Protocol. The major one is its simplicity, the fact that there is no need for any software to run on the computer that needs to communicate with the Internet. This saves costs and time and enables features like ‘always on’ functionality that may otherwise be unavailable.
An internet draft is a proposal that has not yet been formally approved as stable or final and is used as a testing ground for new service enhancements, protocol modifications and new standards. Internet Explorer and Firefox use SIP internet protocol to connect to websites, while Chrome and Safari use different transport protocols based on the one in the internet-draft. In order to test the proposed features of any new protocol, an internet-draft must be submitted to W3C for review and inclusion in the standard. At this point, people involved in SIP Internet Protocol development divide the process into two phases: drafting and testing.
One of the main considerations while designing SIP is to keep network traffic low and avoid overloads. To do this, the SIP header has to be small enough and easily understood. The SIP header can be broken into eight small sections called a hop by hop and contains the following fields: destination address, source address, non-network address, field indicating the reserved network block, the size of the buffer, the checksum, and last but not least the secret key. The header is then sent along with a SIP packet that starts with the SIP host name and port number.
SIP uses the IP protocol family named SIPv4. Unlike traditional IP networking where there is only one IP network per physical device, SIPv4 allows multiple IP networks to exist on a single physical network. Each network has unique IP addresses. For example, while a network called eth1 operates on the IPx format, every device connected to it will have its own IP address. To make matters worse, the traditional IP networks are not compatible with the newer SIP protocols, which is why it is difficult to access some of the features available in SIP like SIP packets with opaque IP addresses.
SIP packets have to be able to negotiate with routers and IP servers, since these IP servers and routers are exclusively allocated by the Internet Service Provider (ISP). To do this, they use standard protocols called IP Subnet unicast and IPv6 addresses. Standard IP networking is useful only for local area network (LAN) operation, where in the local area has to be reachable to all subscribers. On the other hand, SIP offers a global network with twelve different subjects, which means that each subscriber can have his or her own IP address within a bigger area.
The first part of the process starts with the IP prefix. This consists of seven bits that are used to uniquely identify the source network and each of the local subnet masks. The next part is the destination address that is used to forward or return these SIP packets. In the traditional IP networking, the routers have to search for the closest IP address that is close to the one being requested. However, since the majority of the SIP systems use different IP addresses for every client, such a process is rarely necessary.
Next, the IP checksum is used to authenticate and verify the incoming packets. It checks the IP addresses of every outgoing packet and creates a unique checksum. The checksum also includes the length of the outgoing packet as well as the number of unique IP addresses for each packet. The checksum is also used as a security check of the system. If an IP address checksum matches with the number of allowed IP addresses, the server determines if it can handle the request or not.
On a lighter side, during the ILS session, the session is controlled and maintained by the administrator. The system will check all the processes and determine the parameters needed for it to run smoothly. During this time, the system may also be susceptible to denial of service attacks due to too many clients connecting to the server at the same time. To prevent this from happening, the IP addresses of all the clients are submitted into the system. A Historic SERVER check, however, may also be set to run periodically for historical information.