Module 5: IP Routing II Flashcards
Describe Exterior Gateway Protocol (EGP)
AS (Autonomous System)
collection of routers under same technical / administrative domain
local traffic
traffic within an AS
stub
a single connection to one other AS
multihomed AS
connections to > 1 AS, may refuse to carry transit traffic
transit AS
connections to > 1 AS, may refuse to carry transit traffic
Some facts about AS
A collection of routers under the same administrative domain
Can be large global ASPs or small regional networks
An AS can connect to more than one other AS
Tier 1 Networks
Tier 2
peers with some networks, but still purchases IP transit to reach at least some portion of the internet
Tier 3
Solely purchases transit from other networks to reach the internet
Who speaks BGP?
What is the purpose of BGP?
To share connectivity information across ASes so that at the AS level you know how to send traffic from one AS to another
What are two constraints of BGP?
Scaling
Autonomy (policy and privacy)
Why is LS not ideal for the BGP protocol?
requires sharing of complete network information
information exchanges doesn’t scale
all policies exposed
Why is DV better for BGP?
scales and retains privacy
BUT –
cannot implement policy (only know next hop)
cannot avoid loops if shortest path not taken
What do we run over BGP?
Path Vector Protocol
Advertising Routes
What are the basic messages in BGP?
Issues with BGP
BGP runs over what protocol?
TCP
What are some addressing protocols?
Getting an IP Address with Dynamic Host Configuration
Describe the Address Resolution Protocol (ARP)
How to scale internetwork Routing?
Describe class-based addressing schemes
what is the problem with the class-based addressing approach?
Classless Interdomain Routing (CIDR)
What does CIDR allow us to do?
a more flexible way of reducing the routing table size
What are two effects of CIDR?
- reduce the routing table size
- reduce the routing advertisement
Router forwards packet according the most specific forwarding information, _________________.
What is the motivation of the transport protocol?
what are the services provided by TCP?
What are other services provided by TCP?
how does UDP contrast to TCP?
what are the advantages of UDP?
disadvantages of UDP
where do we use UDP?
headers!
UDP Service & Header
TCP Header
