104 4 Software-Defined Networks Principles and Applications
Region 7
Region 6
Level 1
Level 2
Level 3
HS5
HS1
HS2
S1
Region 5
Region 1
Region 2
Region 3
Region 4
cN5
cN1
cN2
cN3
cN4
cN6
cN7
Control nodes (cNodes)
HiRE/physical switch
Abstraction
App (AbsApp)
Optimization
App (OptApp)
TE enforcer
App (EnfApp)
Basic services
Parent cNode
a) Hierarchical control logic structure
(b) Control node (cNode) design
1: Flows and logical fabrics
2: TE results
S2
S3
S4
Figure 4.16 SdnTE network architecture.
is a new software abstraction over a physical/logical switch topology.
In Figure 4.16, switches in region 2 are abstracted as hSwitch HS2 in
region 5. hSwitch ports are logical, each corresponding to one or more
border switch ports in the constituent physical topology.
4.6.1.2 Control Node Design
The software architecture of cNodes are illustrated in Figure 4.16
that consists of three applications: Abstraction App (AbsApp), Flow
optimization App (OptApp), and TE enforcer App (EnfApp). AbsApp
is responsible for communicating with the parent cNode by building
and through the abstract hSwitch. TEOpt makes local TE decisions
for flows appearing in its region. Although SdnTE is flexible to
support different TE techniques (e.g., greedy, linear, and nonlinear),
we focus on a designing multipath flow optimization using LP: TEOpt
iteratively collects flow requests in the next interval from its region