EE555 – Broadband Network Architectures (Spring 2009)
Homework 3  Optical Networking
Due: Feb 27, 2009
Q1.
The logical topology shown is implemented on an eight
node passive star optical network. Each link represents the
ability to transmit in either direction, i.e., there is a (logical) link
from 000 to 001 AND a (logical) link from 001 to 000.
a)
For a uniform traffic matrix (every node sends to every
other node at the same rate), what is the average path
length in the virtual topology?
b)
How many wavelengths are needed to implement this
network?
c)
Each wavelength can carry an OC48 (2.5 Gbps)
channel. What is the maximum endto end traffic that
the network can handle for a uniform traffic pattern?
Q2.
Consider a 5 node unidirectional optical ring network. A SONET OC192 framing structure over a
single wavelength is in used between adjacent nodes in the ring. There is a SONET ADM and a router
attached to each node. There are two options for configuring the network.
A: The virtual topology is a bidirectional 5 node ring (so there are 10 circuits.)
B: The virtual topology is a fullyconnected mesh, i.e., a dedicated circuit is provisioned between each
source and destination (a total of 20 circuits.)
a)
If all circuits have the same capacity and assuming all partitionings of OC192 (e.g. OC3, OC7,
etc) are possible, what is the maximum capacity that can be assigned to circuits in each design?
b)
Given the assignment in a) and assuming a uniform traffic matrix, find the “network average
delay” for the two networks. Plot your result as a function of the total network traffic
γ
.
Q3.
Consider a unidirectional 4 node ring network (1
→
2
→
3
→
4
→
1) that uses a CWDM system
where each lambda carries an OC48 SONET payload. The traffic requirement matrix is given
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 Spring '08
 Silvester
 Ring network, Network topology, SONET ADM, uniform traffic matrix, node ring network

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