What is the Internet ? Simply speaking the Internet is inter connected networks sharing information using standard protocol stack. However the modern internet is much more than inter connected networks. The Internet has become platform rapid and accelerated human evolution. It has been invaded into every aspects of our lives making both positive and negative consequences.
In despite of advancement in technologies and impact on our lives, fundamentally speaking the Internet is an inter connected networks even after 30 years from its birth. Computer networks depend on two different kind of protocols for traffic propagation.
1. Routed Protocols
2. Routing Protocols
TCP/IP is the well known “routed protocol” used in modern networks. It is also responsible for majority of global Internet traffic. It can carry almost any kind of internet based services including but not limited to world wide web, electronic mail, secure connectivity and streaming media. On the other hand, “Routing Protocols” provide path to propagate TCP/IP and similar transports (e.g. UDP, ICMP).
Well known routing protocols are OSPF, IS-IS, EIGRP, RIP and BGP. All the routing protocols (except BGP, which we are going discuss later) provide reachability information for each other networking hop so end hosts can reach remote service at network address. RI or reachability information is passed to each networking hop so individual hop can take the decision on packet switching towards remote service.
So what is the uniqueness in the BGP? Instead of passing reachability information from hop to hop, BGP passes reachability information from network to network basis. BGP a.k.a Border Gateway Protocol is the de-facto routing protocol of the Internet. We can not have working Internet without BGP.
Individual network can consist of hundred of thousands of network devices. Each and every network is managed, administrated and operated by independent autonomous entities. These autonomous entities could be either ISP (i.e. Internet Service Provider) or Company/Organization/Government participate in data origination and trafficking.
Similar to network addresses are assigned to individual network hop, BGP introduces numbering mechanism for each independent network. These numbers are called “Autonomous System Number”. Worldwide ASNs are assigned by “Internet Assigned Numbers Authority” or IANA through “Regional Internet Registries” or RIR. The word “Autonomous” in ASN emphasizes autonomy in decision making inside individual network. However, Inter Autonomous System connectivity policies must be mutually agreed between connected parties.
In summary, the Internet is highly autonomous networks inter connected to create global information super highway. Absolute autonomy can be expected inside individual network in related to traffic propagation policies and paths. This autonomy secure the Internet’s distributed architecture while preserving freedom of the information propagation between networks.
Last but not least, Let’s look into few real world examples for Autonomous System interactions in the Internet.
All the links provided above are information/learning purpose only and accuracy is not guaranteed.