ECE 544 Project3

Amith V.S

Pavan Kulkarni

Suneet Dixit

Assumptions and Address Scheme Assumptions

Routers do not fail in the life time of the Network. Router to Router Links do not fail in the life time of the

Network. IPs of all the Routers are preassigned. Routers assign IPs to all the hosts in the Network.

Naming scheme and eventual address scheme Edge routers are assigned IPs in the form X.X.n.0 where n

ranges from 1-254. End hosts are assigned IPs in the form X.X.n.h where n is the

subnet number as assigned above and h ranges from 1-254 (since no. of hosts connected to network N < 255).

Content files are identified by their content ID ranging from 1-254 (since no. of contents in the network K < 255).

Bootstrapping and Discovery

Modified Link State Algorithm - MLSF Extends the functionality of Link state algorithm

to support the functionality of Content Provider Network.

Initially each of the edge router sends the contents that are available in their subnet along with the distance vector to their adjacent routers.

After the convergence of the network each of the router will have a table as shown below:

Time Stamp

Destination Cost Next Hop Contents

Bootstrapping and Discovery Discovery

Routers discover other routers with Hello Packets as shown Below :

Edge routers discover their hosts and contents present in them with Hello Packets as shown below :

Router Source IP Content Indicator Array

32 Bits 256 Bits

Host IP address Content ID array

32 bits Variable Length

Baseline Algorithm

Content routing algorithm Once the Modified Distance Vector Algorithm – Routing

Table is established in each of the Router, the network is now ready to respond to the get(ContentID) request.

How to route a content-request packet? For each of the request issued by a host, the packets are

generated in following format:

The edge router receives this packet and converts it into

Router-Router request packet as shown below:

Host Source IP Flag Content ID

32 Bits 8 bits 8 bits

Host Source IP Destination Router IP

Flag Content ID

32 Bits 32 Bits 8 Bits 8 Bits

Baseline Algorithm How to route a content-request packet(cont..)?

This packets traverses the network through the shortest path and reaches the edge router which is connected to the host which has the content.

Each edge Router has a table mapping the Hosts IP address to the contents the host has.

Referring to this table the packet is forwarded to the appropriate host.

The host extracts the packet and gets the content ID requested and generates the response packet as shown

Host Destination IP

Flag Content ID Content

32 Bits 8 Bits 8 Bits Upto 1466 Bytes

Baseline Algorithm How the content is actually delivered?

While the request packet traverses through the network it updates the bread crumbs table as shown below present in each router :

The response packet refers the bread crumbs table to get the next hop.

How network is updated when a host has a new content? When a host has a new content, a new content packet is

generated as shown and forwarded to the edge router:

Destination IP address Next Hop IP address

32 Bits 32 Bits

Host Source IP

Flag Content ID Time Stamp

32 bits 8 bits 8 bits 32 Bits

Baseline Algorithm How network is updated when a host has a new

content(cont..)? The edge router gets this packet replaces the

host IP address with its own IP address and broadcasts the packet to all the connecting Routers.

This is continued as Spanning tree algorithm with Time Stamp as the update parameter. Thus all the router's MDVA table is updated.

How network is updated when a host deletes a content(cont..)? The same procedure is followed as above with

the flag set to delete content.

Data Transfer and Reliability

Message Forward Host – Router is Unicast Hello Packets and Update Packets between

Routers is Multicast

ARQ Scheme Hop-by-hop acknowledgement scheme is being

used at every router

Advantages

Algorithm: A modified version of the Distance Vector Table is being used which efficiently calculates the shortest path to the host which has the required contents

Scalability: The method employed can be extended by using the unused bits of the IP address making the system scalable

Latency: The method employs bread crumbs to send data back to the requesting host. In this way a low latency is maintained

Disadvantages

As Distance Vector Algorithm is a decentralized routing algorithm, it takes time to converge the table

Hop-by-hop acknowledgement scheme may introduce latency

Appendix: Network Architecture

Example scenarios for analysis purposes:

H1

H2

H3

C1C1 C2C2

C3C3

R1 R2 R3 R4

R5

Scenario 1: @host_H2: get (content_C3)

Appendix: Network Architecture

H1

H2

H3

C1C1

C2C2

C2C2

C3C3

C3C3

R1 R2 R3 R4

R5

Scenario 2: @host_H1: get (content_C2)

Appendix: Network Architecture

H1

C3C3

Scenario 3: @host_H1: get (content_C1)

H2 H3 H4

C1C1 C1C1C2C2

C1C1