There are of two types:

1. Intra-domain protocol :

• communication happens within the autonomous system

• RIP, OSPF
  1. Inter-domain protocol :

• communication between two or more autonomous system

• BGP

Unicast Routing Protocols

1. RIP (Routing Information Protocol)
   • uses distance vector algorithm (Bellman-Ford)
2. OSPF (Open Shortest Path First)
   • uses link state algorithm (Dijkstra’s Algorithm)
3. BGP (Border Gateway Protocol)
   • uses path vector algorithm

OSPF

• We use Dijkstra’s algorithm to find out the cost
• Maintains a database called as Link State Database (LSDB)
• Large networks are divided into small areas to avoid traffic (main area is Backbone area
• has WAN connection, and is 0)

BGP

• Embedded in the borders of the autonomous systems
  1. iBGP
• internal
  1. eBGP
• external
• Determines the best path in a network
• Path attributes
• determines the cost or the next network through the next host and forwarding table (its the associated cost)
• path at which data has to be transmitted

Messages :-

• Hello message (Type 1)
• Database description (Type 2)
• Link-state request (Type 3)
• Link-state update (Type 4)
• Link-state (Type 5)

[! imp for third unit]

• HTTP request and response

• DNS and FTP