Telecommunications Signaling
Highlights the conventions of signalling systems and provides a detailed assessment of their architecture.
TABLE OF CONTENTS Telecommunications Signaling
18.4: Internet Protocol (IP)
18.4 Internet Protocol (IP)
18.4.1 IP Service
The Internet Protocol (IP)2 fits within the Internet Layer of the IP Model, as illustrated in Fig. 18.3. IP makes use of the Link Layer to provide suitable media, etc. IP offers a routing service to the higher layers, routing data between nodes in a connectionless manner. IP is kept simple and it does not guarantee a quality of service to its users. For example, the users of IP have to determine if IP packets are corrupted or mis-sequenced and take appropriate actions.
18.4.2 IP Formats
The format of an IP Packet consists of a Header followed by data. The header format is based on 32-bit fields and is illustrated in Fig. 18.5.
| Version (4) | Traffic Class (8) | Flow Label (20) | |
| Payload Length (16) | Next Header (8) | Hop Limit (8) | |
| Source Address (128) | |||
| Destination Address (128) |
Figure 18.5: IP Packet Header Format
( ) = number of bits
The Version Number indicates the form of IP Protocol that is being used, e.g. Version 6. Thus, hosts and routers can discriminate between old and newer versions of the IP Protocol.
The Traffic Class is used by hosts and routers to determine the priority of the IP Packet. The value of the Traffic Class is selected by a higher-layer function at the originating host, but the value can be changed by routers as the packet is transferred through the network.
A 'flow' is a sequence of packets that an originating host wishes to be...
Copyright The Institution of Electrical Engineers 1999 under license agreement with Books24x7
