Lecture 1: Autonomous Systems Flashcards
What is an autonomous system?
A group of routers under common administrative control
How are autonomous system uniquely identified by?
Autonomous System Number (ASN)
Relationships between autonomous systems are
typically sorted into ___ and ___ between two autonomous systems
- Peer relationships
- Transit relationships
What does a peered relationship between autonomous systems mean?
Traffic can be exchanged without cost
What does a transit relationship between autonomous systems mean?
One system sells access to another system at a price (an ISP)
What is a stub network?
An autonomous system that
is only connected to one other
autonomous system
What is a transit network?
An autonomous system that offers connections from one autonomous system to another
What does BGP handle?
The exchange of routing information
- What routes exist
- Their performance
- The types of traffic allowed on them
What are the 3 network tiers?
- Tier 1
- Tier 2
- Tier 3
What is a Tier 1 Network?
Networks are all peered to each other, and offer transit services to smaller Tier 2 networks
What is a Tier 2 Network?
Networks offer transit and peering between each other, as well as to Tier 3 networks
What is a Tier 3 Network?
Networks are usually stubs such as end users or small ISPs
What tier is typically considered part of the backbone of the WWW?
Tier 1
What tier is often provided by large ISPs or network resellers
Tier 2
Which network tier can reach ~100% of the network without paying anything?
Tier 1
