Caching and Mobility Support in a Publish-Subscribe Internet - - PowerPoint PPT Presentation

caching and mobility support in a publish subscribe
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Caching and Mobility Support in a Publish-Subscribe Internet - - PowerPoint PPT Presentation

Caching and Mobility Support in a Publish-Subscribe Internet Architecture George Xylomenos, Xenofon Vasilakos, Christos Tsilopoulos, Vasilios A. Siris, and George C. Polyzos Presented by Max Nicosia Motivation Need for Mobility


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SLIDE 1

Caching and Mobility Support in a Publish-Subscribe Internet Architecture

George Xylomenos, Xenofon Vasilakos, Christos Tsilopoulos, Vasilios A. Siris, and George C. Polyzos Presented by Max Nicosia

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SLIDE 2

Motivation

  • Need for Mobility
  • Change in usage model

○ From sharing Resources -> Info (regardless of end-point hosting it) PSI claims:

  • Scaling not affected by addressing or

routing assumptions

  • Supports native multicasting
  • Asynchronous nature and caching help with

MN handoff

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SLIDE 3

Architecture Overview

Naming:

  • Scope Identifier (SID)
  • Rendezvous Identifier (RID)

Network Primitives:

  • Publish
  • Subscribe
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SLIDE 4

Architecture Overview (cont)

Functions (3):

  • Rendezvous
  • Topology Management
  • Forwarding
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SLIDE 5

Example Retrieval

Steps:

  • 1. Producer publishes item
  • 2. Consumer subscribes
  • 3. Subscription is propagated to the

Rendezvous Function

  • 4. Topology Manager constructs forwarding

path -> Forwarding Identifier (FID) and returns it to Publisher (notification)

  • 5. Publisher starts transmission
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SLIDE 6

Network Design

4 Types of Elements:

  • 1. Hosts
  • 2. Forwarding Nodes (FNs)
  • 3. Rendezvous Nodes (RNs)
  • 4. Topology Managers (TNs)

Key Benefits (Hosts behind gateway RN):

  • Increased security and privacy
  • Reduced control overhead and rendezvous traffic
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SLIDE 7

Forwarding

  • Using LIPSIN

○ On-path links encoded in fixed size bit string

(Bloom Filter) -> FID

○ Included in packet

  • Packets can be delivered over multicast

trees by adding tree links to the FID

○ No extra state in the network is required

  • Topology Managers can enforce routing

policies

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SLIDE 8

RENE and Topology Management

  • Made out of multiple RNs

○ Built from FNs and RNs talking to TMs ○ Link State Announcements (LSA)

  • Topologies built used for intra-domain

routing

  • TMs send FIDs with paths
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SLIDE 9

Transport

  • RNs maintain list of subscribers (state)
  • New subscribers are added to FID
  • Documents (reliable delivery)

○ TMs compute bidirectional FIDs

  • Push-based
  • Pull-based
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SLIDE 10

Caching and Replication

  • On-path Caching
  • Off-path Caching
  • Content Replication
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SLIDE 11

On-path Caching

  • Requests can be served by FNs on the path
  • Prevent feedback implosion of multicast errors
  • Possible to use on the Internet at the Application layer

○ Requires proxy server for Browser

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SLIDE 12

Off-path Caching

  • Take advantage that any node can serve request
  • RENE can decides to cache or not to cache info
  • Additional overhead -> announce to local RENE
  • Hard to achieve on the Internet as it needs coordination

between various application-level caches

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SLIDE 13

Content Replication

  • Used to minimise inter-domain traffic and improve user

experience

  • Does not rely on DNS tricks like on the Internet
  • Can also exploit off-path caching
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SLIDE 14

Mobility and Caching

  • Decoupling from Time and Space
  • Re-issue subscriptions for missed data

○ RENE takes care of redirection to caches

  • Micro-mobility:

○ Use off-path caches to support MNs -> requests forwarded after handoff to cache ○ Assigned based on topology or forecasting

  • Macro-mobility:

○ Set caches in neighbouring networks (expensive)

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SLIDE 15

Conclusions

  • Information-centric architecture
  • Individually identified items can be cached

at Network Layer

  • Asynchronous nature of PSI make it

mobile-ready

  • Constantly evolving architecture
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SLIDE 16

Critique

  • No performance analysis about the

impact on the network on various conditions

○ Possibly not very applicable in many cases

  • Privacy concerns about data being

replicated without any control

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SLIDE 17

Questions?