CS716
Advanced Computer Networks
By Dr. Amir Qayyum
1
Lecture No. 44
2
Overlay Networks
3
Overlay Network Layered on Top of
a Physical Network
4
Overlay Nodes Tunnel Through
Physical Nodes
IHdr
...
...
IHdr
A
IHdr
B
OHdr
IHdr
...
C
OHdr
IHdr
...
5
...
A
5
R1
B
Multicast
Trees
Mapped
Onto a
Physical
Topology
50
5
C
5
D
R2
5
(a)
A
C
R1
R2
B
D
(b)
A
C
R1
R2
B
D
(c)
A
C
R1
R2
B
(d)
6
D
Multicast Tree Embedded in an
Overlay Mesh
A
C
B
D
A
C
B
D
7
Triangular Inequality in Networks
10
70
125
8
Peer to Peer Network
9
128bit Nodes and Objects ID Space
2128
1 0
objid
nodeids
10
Locating Object by Routing
d471f1
d46a1c
d467c4
d462ba
d4213f
d13da3
65a1fc
locate(d46a1c)
11
Routing Table at Nodes
12
Adding Node to the Network
d471f1
d467c4
d462ba
d46a1c
d4213f
addnode(d46a1c)
d13da3
65a1fc
13
Content Distribution Network
Site A
Site B
Site C
aaa.com
bbb.com
ccc.com
Backend
servers
Cache
Geographically
distributed
surrogate
servers
Redirectors
Clients
14