Transcript slides - Winlab

ECE 544 Project3
Aayush Patidar
Ashwin Ramakrishnan
Manoj Juneja
Assumptions and Address Scheme


Assumptions
 End hosts can only connect to routers.
 Same content is available at multiple end nodes.
 Routers are statistically configured.
 Hosts store content on receiving other contents.
 Cost of the link between adjacent routers is 1.
Naming scheme and eventual address scheme
 Router -> 0-254
 End hosts ->0-255
 Content ID-> 0-255
Baseline Algorithm

Content routing algorithm
 Contents are advertised by hosts through their routers
which in turn advertise to neighboring routers. (Similar
to RIP)
Content Request
 To route a content request packet, the content id of
the packet is seen and the next hop is looked up on
the forwarding table.
 Best amongst the multiple hosts are decided by hop
count
 The content once found is delivered in a packet which
contains the content and the reverse of the list of
traversal.
Baseline Algorithm Contd.

Content Not Found

At some point in network, Request for content Ci
reaches a router that hosted it previously(just
deleted) will send a Content Not Found Packet in
the reverse direction and every node in the
reverse path will update it’s CRT and look for
alternative path and sends request over it.
Packet Format
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
Type
Length
CID
Hop
Count
Update Packet
Content Request Packet
Type Len
CID
Router ID (Stack)
Packet Format
Type Len

CID
Data Packet
Data
Router ID (Stack)

Content Not Found Packet
Type Len
CID
Router ID (Stack)
Content Routing Table
CID
Next Hop
TTL
Hop Count
C1
R1
20
1
C2
R5
30
1
C2
R3
22
2
C3
R5
30
1
C3
R3
25
2
C2
H2
C3
C1
C2
R5
C3
H1
R1
R2
R3
R4
H3
Data Transfer and Reliability


Message Forward
 Message forwarding used is Unicast.
 Types of Packets :
 Update Packet
 Content Request Packet
 Acknowledgement Packet
 Content Not Found Packet
 Data Packet
ARQ Scheme
 The ARQ scheme used is Hop by Hop and Stop
and wait protocol is used.
Advantages and Disadvantages

Advantages :







Reliable due to Stop-and-wait protocol and the Content Not
Found packet
Exhaustive search due to Content Not Found packet
NO IP : content based rounding
Simple Architecture
Stateless routers
Minimal Network Utilization
Disadvantages :

Slower than broadcasting every data request
Example Scenario

@host_H1: get (content_C2)
C2
H2
C3
C1
C2
R5
C3
H1
R1
R2
R3
R4
H3
Appendix: Network Architecture

Refer to the following example scenarios for
analysis purposes:
Scenario 1: @host_H2: get (content_C3)
H2
C1
C2
R5
C3
H1
R1
R2
R3
R4
H3
Appendix: Network Architecture
Scenario 2: @host_H1: get (content_C2)
C2
H2
C3
C1
C2
R5
C3
H1
R1
R2
R3
R4
H3
Appendix: Network Architecture
Scenario 3: @host_H1: get (content_C1)
H1
H2
H3
C1
H4
C1
C2
C1
C3