Overview
This lecture introduces exterior gateway protocols, autonomous systems, and the roles of IANA and ASNs in internet routing.
Exterior Gateway Protocols (EGPs)
- EGPs are used to transfer data between routers at the edges of different autonomous systems (AS).
- Unlike interior gateway protocols (IGPs), EGPs operate between organizations, not within a single organization's network.
- EGPs are essential for the internet to function by enabling network interoperability.
Autonomous Systems & Internet Routing
- The internet is composed of many interconnected autonomous systems (AS), each a defined collection of networks.
- Core internet routers focus on forwarding traffic to the correct edge router of the destination AS.
- Autonomous systems are identified by unique Autonomous System Numbers (ASNs).
IANA and Address Assignment
- The Internet Assigned Numbers Authority (IANA) manages global IP address and ASN allocation.
- Centralized allocation prevents conflicts and chaos in IP address usage.
Autonomous System Numbers (ASNs)
- ASNs are unique 32-bit numbers assigned to autonomous systems for routing purposes.
- Unlike IP addresses, ASNs are usually represented as a single decimal number.
- ASNs do not need to be segmented into parts like IP addresses, as ASN structure does not denote network/host portions.
Key Terms & Definitions
- Exterior Gateway Protocol (EGP) — Protocol for routing data between different autonomous systems.
- Autonomous System (AS) — A group of networks under a single organization's control, with a unified routing policy.
- IANA (Internet Assigned Numbers Authority) — Organization that oversees global IP address and ASN assignment.
- Autonomous System Number (ASN) — A unique 32-bit identifier for an autonomous system.
Action Items / Next Steps
- Review the basics of IP addresses, ASNs, and routing for further understanding of internet infrastructure.