BGP and inter-domain routing in Computer Networks - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does BGP stand for and what is its primary purpose?

BGP stands for Border Gateway Protocol. Its primary purpose is to exchange routing information between different autonomous systems (AS) on the internet, enabling inter-domain routing.

beginner

What is an Autonomous System (AS) in the context of BGP?

An Autonomous System is a collection of IP networks and routers under the control of a single organization that presents a common routing policy to the internet.

intermediate

How does BGP differ from interior routing protocols like OSPF?

BGP is used for routing between different autonomous systems (inter-domain), while OSPF is used within a single autonomous system (intra-domain). BGP focuses on policy and path selection, not just shortest path.

intermediate

What is the role of BGP attributes in route selection?

BGP attributes like AS_PATH, NEXT_HOP, and LOCAL_PREF help routers decide the best path to a destination by applying policies and preferences.

intermediate

Why is BGP considered a path vector protocol?

BGP is called a path vector protocol because it maintains the path information (sequence of AS numbers) that data must traverse to reach a destination, helping prevent routing loops.

What does BGP primarily manage?

A Routing within a single network

B Switching data packets inside a LAN

C Routing between different autonomous systems

D Encrypting internet traffic

BGP manages routing between different autonomous systems, enabling inter-domain routing.

Which of the following is NOT a BGP attribute?

A LOCAL_PREF

B TTL

C AS_PATH

D NEXT_HOP

TTL (Time To Live) is not a BGP attribute; it is a field in IP packets.

An Autonomous System is best described as:

A A group of networks under one administrative control

B A single router on the internet

C A type of firewall

D A protocol for encrypting data

An Autonomous System is a group of networks managed by one organization with a common routing policy.

Which protocol is used for routing inside an autonomous system?

A BGP

B FTP

C HTTP

D OSPF

OSPF is an interior gateway protocol used for routing within an autonomous system.

Why does BGP keep track of the AS_PATH?

A To prevent routing loops

B To speed up packet delivery

C To encrypt data

D To assign IP addresses

AS_PATH helps BGP prevent routing loops by tracking the sequence of ASes a route has passed through.

Explain how BGP enables communication between different networks on the internet.

Think about how different organizations connect their networks.

Describe the difference between BGP and interior routing protocols like OSPF.

Consider where each protocol is used and what problems they solve.