Routing%20in%20Multiple%20Layers:%20Opportunities%20and%20Challenges

1
Routing in Multiple Layers Opportunities and
Challenges

• Mostafa Ammar, Srinivasan Seetharaman
• Networking and Telecommunications Group
• College of Computing
• Georgia Institute of Technology

2
Overlays

• P2P Nets
• Service Overlays
• Application Layer X (X multicast, QoS, )
• Virtual Networks (a la PlanetLab, VINI, GENI)

3
Overlays like to do routing!

• Their raison detre
• Performance reasons
• Fault recovery reasons
• Resource management
• To battle lower layer

4
Multi-Layer Routing
C
OVERLAY2 LAYER
E
B
C
OVERLAY1 LAYER
F
E
H
G
A
D
B
A
C
E
F
H
B
NATIVE IP LAYER
D
G
5
Multi-layer Dynamic Routing

• Hello-intervals Native 5 secs
• Failure detection time Native 3 x 5 secs

• Hello-intervals Native 5 secs / Overlay 3
  secs
• Failure detection time Native 3 x 5 secs /
  Overlay 3 x 3 secs
• ? Overlay will detect first

A
D
C
B
6
Challenge 1 Objective Mismatch

• Conflict in objective between the two layers

AS policy violation
C
OVERLAY1 LAYER
F
E
H
G
A
D
B
A
C
PROVIDER
E
F
H
B
NATIVE IP LAYER
D
CUSTOMER
G
7
Challenge 2 Functionality overlap

• Each layer performs rerouting, with no knowledge
  of which layer leads to optimal restoration

Overlay rerouting
C
OVERLAY1 LAYER
F
E
H
G
A
D
A
B
A
C
E
F
H
X
Failure
B
NATIVE IP LAYER
D
G
Native rerouting
8
Challenge 3 Coexistence issues

• In reality, coexistence is required between
• overlay and legacy apps.
• overlay and other overlay apps

C
OVERLAY1 LAYER
F
E
H
G
A
D
B
A
C
E
F
H
B
NATIVE IP LAYER
D
G
9
Challenge 4 Unconstrained Design

• Higher level of perceived freedom as you go up
• No knowledge of physical constraints optimal
  placement

Essential nodes
C
F
OVERLAY1 LAYER
E
H
G
A
D
B
A
C
E
F
H
B
NATIVE IP LAYER
D
G
10
Virtual network assignment (VNA)

• Problem Statement
• Allowing virtual networks (VNs) to be assigned to
  the substrate network efficiently and on-demand

• Tasks
• Assign VNs to the substrate
• Achieve low and balanced load on both substrate
  nodes and links
• Importance
• Allows for accommodating more VNs with limited
  resources
• Helps to handle dynamic situation

11
Research Opportunities

• Layer-aware design of protocols in all layers
• Sufficient incentive for inter-layer awareness
• Level of awareness and cooperation needs to
  determined
• Improves co-existence/resource sharing
• Virtual network (resource) assignment
• Resource management
• Intelligent placement
• Efficient reconfiguration
• Multi-layer testbed
• that allows control of multiple layers
• That helps meter actual user experience