W7 L1 - Link-State Routing & OSPF

Dynamic Host Configuration Protocol (DHCP)

Goal: Dynamically obtain IP address from network server when it joins a network

Process:

1. Client broadcasts for DHCP until it receives ACK and usable IP address

2. Client accepts IP address

Network Address Translation (NAT)

All datagrams leaving local network have the same source NAT ip address, but different source port numbers.

• In a network, NAT hides private IPs behind one public IP

• NAT translates the internal IPs and Ports to a public IP port for outgoing traffic

• Maintains “translation table” for routing replies back to the correct device

OSPF routing

Uses Dijkstras and adds to it for a real-world application for routing

1. Each router learns about its neighbors

2. Routers flood link-state advertisements (LSAs)

3. Each router builds a full map of network

4. Dijkstras algoithm runs

5. Routing table updated

Hierarchical OSPF

Two-level hierarchy - local area, backbone

• LSAs only flooded in one area

• Each node has detailed area topology