The Wunet Protocol

History of Wunet

The Wunet Protocol is a simplified 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.

This page describes the features of Wunet and gives several examples. These features include:

• Network Virtualization
• Unicast and Multicast Packets
• Virtual Link Rate Guarantee
• Virtual Link Weighted Fair Sharing
• Route Learning
• No-Route Flooding
• Upstream Packet Propagation
• Spoofing Protection

A version of Wunet that is targeted at conventional processors has been implemented in C++. We plan to implement a GPE-only version of Wunet on the GENI deployment of the SPP as a precursor to implementing a fastpath verion involving the NPR.

A Wunet Virtual Network

File:Wunet-simple.png

A Simple Network

labels:  hosts, routers, links

             H11 H12 H13     H21 H22 H23    ...
             | ^ | ^ | ^     | ^ | ^ | ^
             v | v | v |     v | v | v |
               1   2   3       1   2   3

                  R1 4-----------> R2
                     <-----------4
                 6| 5\            6/|5
                  v   \           / v
...
                  R4 ------------> R3
                     <------------

             | ^ | ^ | ^     | ^ | ^ | ^
             v | v | v |     v | v | v |
             H11 H12 H13     H21 H22 H23    ...

A Wunet network contains host nodes, router nodes and links that interconnect the nodes. The figure (right) shows four virtual routers directly connected to each other and each router is directly connected to three hosts.

Each host has one virtual link, and each router has six virtual links. A link between two nodes is virtual in the sense that it is actually a path in the underlying actual network. An example of the actual network might be an IP network where a virtual link is a communication path between two UDP endpoints (i.e., an IP address and UDP port number).

File:Wunet-simple-overlay.png

The Overlay Network

In the figure shown right, XXX

Virtual Links

LT: lnum --> (peerEP, type, padr, bitRate, pktRate)

R1 LT:

lnum	peerEP	type	padr	bitRate	pktRate
1	192.168.1.64:0	host	11	30000	15000
2	192.168.1.65:0	host	12	30000	15000
3	192.168.1.66:0	host	13	30000	15000
4	192.168.2.32:30123	router	200	30000	15000
5	192.168.2.80:30123	router	300	30000	15000
6	192.168.1.32:30123	router	400	30000	15000

Wunet Packet Encapsulation

File:Wunet-encap.png

Wunet Packet Encapsulation

Wunet is a virtual network overlayed over an IP network in which each Wunet packet is carried inside a UDP packet. Although the underlying network need not be IP, we assume in all of our discussion that each Wunet packet is encapsulated in a UDP packet. XXX

A Wunet Packet

File:Wunet-pkt-hdr.png

Wunet Packet Header

A Wunet packet header is four words (16 bytes) long. Note that this version of Wunet has no field for detecting packet or packet header corruption. Damaged packets are silently lost if the underlay network is unreliable (e.g. UDP).

The first word of a Wunet header has XXX fields XXX

There are unicast and multicast DATA packets and multicast SUBSCRIBE and UNSUBSCRIBE multicast packets.

Basic Unicast DATA Packet Routing

RT: (vnet, dst) --> (qnum, quantum, links)

R1					R2					R3					R4
vnet	dst	qnum	link		vnet	dst	qnum	link		vnet	dst	qnum	link		vnet	dst	qnum	link
1	11	0	1		1	21	0	1		1	31	0	1		1	41	0	1
1	12	0	2		1	22	0	2		1	32	0	2		1	42	0	2
1	13	0	3		1	23	0	3		1	33	0	3		1	43	0	3
2	11	0	1		2	21	0	1		2	31	0	1		2	41	0	1
2	12	0	2		2	22	0	2		2	32	0	2		2	42	0	2
2	13	0	3		2	23	0	3		2	33	0	3		2	43	0	3

Basic Multicast DATA Packet Routing

RT: (vnet, dst) --> (qnum, quantum, links)

R1					R2					R3					R4
vnet	dst	qnum	link		vnet	dst	qnum	link		vnet	dst	qnum	link		vnet	dst	qnum	link
1	11	0	1		1	21	0	1		1	31	0	1		1	41	0	1
1	12	0	2		1	22	0	2		1	32	0	2		1	42	0	2
1	13	0	3		1	23	0	3		1	33	0	3		1	43	0	3
2	11	0	1		2	21	0	1		2	31	0	1		2	41	0	1
2	12	0	2		2	22	0	2		2	32	0	2		2	42	0	2
2	13	0	3		2	23	0	3		2	33	0	3		2	43	0	3

Basic SUBSCRIBE/UNSUBSCRIBE Routing

VT: vnet --> (plnk, qnum, quantum, links)

R1				R2				R3				R4
vnet	plnk	qnum	link	vnet	plnk	qnum	link	vnet	plnk	qnum	link	vnet	plnk	qnum	link
1	0	1	1-6	1	x21	1	1-6	1	x31	1	1-6	1	x41	1	1-6
2	4	2	1-4	2	x22	2	1-4	2	x32	2	1-4	2	x42	2	1-4

Route Learning

A router will add a reverse route for any incoming packet with a source address not found in the routing table.

Flooding

A unicast packet with no matching route table entry is forwarded by flooding.

Upstream SUBSCRIBE Packet Propagation

A multicast SUBSCRIBE packet with no matching route table entry is propagated toward the root of its multicast tree.

XXX

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).