1. Chapter 1 Introduction
Networking Architecture Overview

2. Networking Architecture Overview
A Generic Network:
node: switch/router
end-host: telephone/computer/server
More intelligent at the edge nodes
Higher speed at the core nodes
: edge node
: core node
: end-host

3. Networking Architecture Overview
It is all about how to send information/packets between end-hosts:
Routing Protocol
Build the network topology/map
Find one or multiple routes/paths from any node to any other nodes
Build a routing/forwarding table
Two forwarding paradigms
Connection-oriented: set up a virtual path and forward packets along the path
Connectionless: forward packets and let each node downstream figure out how to forward the packets further downstream, known as hop-by-hop forwarding

4. Networking Architecture Overview
More on forwarding paradigms :
Connection-oriented
Build the network topology through a routing protocol: each node tells its neighbors about its connectivity by flooding
Based on the destination end-host’s global address, the routing protocol in the first-hop node finds a route/path to the last-hop node, e.g., a shortest path
The first-hop node uses a signaling protocol to install state information along the path. The state information include incoming and out-going labels with local significance (known as label swapping table) and resources reserved for the path.
The information is sent in the form of labeled packets. At each intermediate node, the incoming label in the packet is matched against the label swapping table to find the outgoing label and output interface to the downstream node.
The incoming label is replaced by the outgoing label before the packet is sent to the output interface downstream, known as label swapping.

5. Networking Architecture Overview
More on forwarding paradigms :
Connectionless
Build the network topology through a routing protocol: each node tells its neighbors about its connectivity by flooding; every node finds a path to every other node and for each destination node, record only the next-hop node along the path to the destination node, resulting in a destination-node-to-next-hop-node mapping table, known as routing/forwarding/longest prefix match (LPM) table. More on LPM later
The information is sent in the form of packets with destination host’s global address attached
At each intermediate node, the destination host’s global address is matched against the LPM table to find the next-hop node and the packet is sent to the next-hop node

6. Networking Architecture Overview
IP internetworking basics: Networks
Shared medium: broadcast domain
e.g., Ethernet and token ring
Use MAC (multiple access control) address to forward frames, known as layer 2 forwarding
Point-to-Point
e.g., packet over SONET (POS)

7. Networking Architecture Overview
IP Internetworking is connectionless
To go from one IP network to another, hop-by-hop forwarding based on the destination IP address is performed, known as layer 3 forwarding
one hop

8. Networking Architecture Overview
Layering concept and addressing schemes:
Internet protocols are designed in layers; the lower layer provides service to its immediate upper layer:
Application L5
Transport L4
Internetworking L3
Data link/MAC L2
PHY L1

9. Networking Architecture Overview
Addressing schemes:
Local address:
VPI/VCI
MPLS labels
Layer 2/MAC address:
A global 48-bit flat address
Cannot scale to large networks
Layer 3/IP address:
A global 32-bit two layer hierarchical address: network part and host part
Network address host address

10. Networking Architecture Overview
Two level routing hierarchies
Intradomain: OSPF, IS-IS, and RIP
Interdomain: BGP
LPM: select the one with the largest number of matched bits
interdomain
intradomain
2.2.3.*
2.2.2.*