The Wunet Protocol

History of Wunet

The Wunet protocol is a paired-down version of the Forest Protocol. Like Forest, Wunet is an overlay network that supports unicast and multicast traffic. But Wunet only supports only a rudimentary form of multicast and there is no provision for error control (e.g., dropped bits). It was developed primarily for educational purposes during the Fall 2009 semester for a course in the Computer Science and Engineering Department at Washington University in St. Louis.

Wunet Concepts

A Wunet network consists of a set of nodes consisting of hosts and router nodes. Each node has a 32-bit virtual node address (vaddr). By convention hosts have virtual node addresses between 1 and 99, and routers have addresses that are typically multiples of 100 (e.g., 300). A multicast address is any 32-bit address with its high-order bit set (i.e., any decimal number greater than 2^31-1 = 2,147,483,647).

• Virtual Node
  • Vaddr (Virtual address)
• Vnet (Virtual Network)
  • Vlink (Virtual Link)
• Subscribe/Unsubscribe

Wunet Features

• UDP Encapsulation:
  • Each packet is encapsulated in UDP packet
• Virtual Addresses:
  • There are unicast addresses(e.g., 21, 200) and
  • Multicast addresses(e.g., 2200110011 = x832303BB) addresses.
    • Any address with high-order bit set is mcast addr; i.e., any decimal number greater than 2^31-1 = 2,147,483,647.
• Packet Types: DATA, SUBSCRIBE, UNSUBSCRIBE
• Routing:
  • Packets are routed by (vnet, vaddr)
• Route Learning:
  • A router will add a reverse route for any incoming packet with a source address not found in the routing table
• Joining/Leaving Multicast Group:
  • A host joins/leaves a multicast group using SUBSCRIBE/UNSUBSCRIBE
• Multicast tree is formed for each vnet through SUBSCRIBE packets that travel up the multicast tree
• Missing Routes:
  • Unicast Data: Flood all downstream links when there is no route.
  • Multicast Data: Send subscriptions upstream when there is no route.