Transcript (slides ) - UCL Computer Science

Scalable Signalling Support for
Overlay Networks
Yangcheng Huang, Saleem N. Bhatti
Dept of Computer Science
University College London
01/12/2004
IEEE ICON 2004
Background
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Overlay Networks
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P2P Searching
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RON: Application-layer Policy Routing
X-Bone
Pier
Chord
Pastry & Bamboo
OverQoS: Offering Internet QoS Using Overlays
(HotNets 2002 by L. Subramanian et al)
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“an overlay network can indeed provide certain forms of
QoS”, without “any changes to data or control planes of IP
routers” between nodes
IEEE ICON 2004
Overlay Networks
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What overlays could do
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Easy to deploy
Providing application-layer control mechanisms to
allow flexibility
What overlays could not do
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No (enough) solutions to manage underlying
network resources
More complexity in data sharing and state
management
→ Towards a general distributed
information management plane
IEEE ICON 2004
Scalable Signalling Underlay
To find out mechanisms to manage underlying
network resources through exchanging state
information between nodes
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Applying a decentralized “peer-to-peer” style
searching and discovering engine into
management and control plane of the overlay
network
IEEE ICON 2004
Design Principles
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Scalability
Resilience
Decentralized architecture
Modularity and isolation
Data integrity
Security
IEEE ICON 2004
Entities
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Signaling Point (SP)
Signaling Forwarding Point (SFP)
Signaling Initiating Point (SIP)
Signaling Sink Point (SSP)
Signaling Path
Signaling Underlay
IEEE ICON 2004
Architecture
Signalling
Sink Tree in
AS1
Leaf
Signalling
Nodes
Decentralized
Cross-domain
Signalling
Root
Signalling
Nodes
Leaf
Signalling
Nodes
Signalling
Sink Tree in
AS2
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Signalling
Sink Tree in
AS3
Mechanisms
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DHT based Data Storage Network
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P2P query mechanism
IEEE ICON 2004
DHT Based State Storage
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In every signaling point (SP), there are one or
several DHTs. And network state information is
stored in these DHTs.
In the key field, it defines two types of data: IP pairs
and IP sub network.
In value field of DHT are
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values of link characteristics, if targeted link is in local
domain (Data Item);
other SPs’ IP address, which store the desired data of link
characteristics, if targeted link locates in other domains
(Pointer Item)
IEEE ICON 2004
DHT Based State Storage
In order to differentiate these two types of values
and also to label the content of value field
Data _ Type
1
0 0 0 0 0 11
Data _ Flag
Content _ Flag
IEEE ICON 2004
Mechanisms
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DHT based Data Storage Network
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P2P Query Mechanism
IEEE ICON 2004
State Query
Query Engine
IEEE ICON 2004
State Query
Query Dissemination
 Flooding based forwarding
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NodeID-approaching mechanism
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Costly
Suitable for “highly replicated items”
IP address as NodeID
Still very preliminary
Complex P2P Query Processing is on the
way
IEEE ICON 2004
Potential Problems
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Overload
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Seems huge, in order to keep network state
information up-to-date.
Can be reduced by query aggregation etc (on the
way)
Query Latency
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Acceptable in smaller networks
Large-scale networks with millions of nodes?
IEEE ICON 2004
Future Work
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Investigating the average delays in large
networks
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With increasing network nodes, the delay may
increase sharply
Investigating the overload-reducing
mechanism, and try to lower the updating
traffic
Architectural issues on how to fit the
proposed design
And much more …
IEEE ICON 2004
Thanks
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Any questions?
IEEE ICON 2004
Modularity and Isolation
Application Oriented Interface Definition
Signalling Kernel Function Definition
Host Specific Supporting Module Definition
Low
Bandwidth
Supporting
Module
(Ultra)
Broadband
Supporting
Module
IEEE ICON 2004
Wireless
Supporting
Module
Potential Problems
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Delay in state distribution/query
Signalling
Sink Tree in
AS1
Leaf
Signalling
Nodes
Decentralized
Cross-domain
Signalling
Root
Signalling
Nodes
Leaf
Signalling
Nodes
Signalling
Sink Tree in
AS2
Signalling
Sink Tree in
AS3
IEEE ICON 2004