The cache-and-forward network architecture for efficient mobile content delivery services

in the future internetSanjoy Paul, Roy Yates, Dipankar Raychaudhuri, Jim Kurose

Jang, Donghyun2011/4/4

dhjang@mmlab.snu.ac.kr

1/21

Introduction System overview CNF Protocol details Performance summary Conclusion

2/21

Table of contents

Representative Future Internet research project◦ NSF FIND and GENI in the U.S.◦ FP7 Future Networks and FIRE in Europe

This paper presents the initial results of an NSF FIND project

The initial results focus on designing a clean-slate network architecture for efficient delivery of media content to mobile users

3/21

Introduction

~2.5 billion cell phones vs. ~500 million wired PC

Smart phones and PDA proliferate rapidly The number of Internet transactions from

mobile devices may be expected to surpass those from wired network PC’s over the next 5-10 years◦ Shift of end-users from wired to mobile

4/21

Why should we focus onmobile contents?

VS

Internet usage pattern◦ Communication => contents service (delivery of

large file) Need next-generation Internet protocol

service optimized to support media content delivery to mobile user

5/21

Why should we focus onmobile contents?

Existing Internet protocols (e.g., TCP/IP) are not well-suited for mobile content services

TCP model assumes a contemporaneous source-to-destination path◦ Mobile users experience intermittent and

unreliable access over wireless channels TCP model was originally designed to

support point-to-point data services◦ It is not suitable for multipoint content

dissemination

6/21

Why do we need new architecture?

To solve the problems of TCP/IP architecture◦ Facilitate opportunistic transport on a hop-by-hop

basis rather than end-to-end streaming of data Hop-by-hop transport model implies large

in-network storage (cache) of content files This is basic idea of the cache-and-

forward (CNF) network architecture

7/21

Main idea

Each node has a large storage cache CNF router may either be wired or wireless,

also mobile (especially, mobile CNF router refer to Cache and Carry (CNC) router)

8/21

System overview –CNF and CNC router

CNC

Network serves two functions◦ Pull: Mobile end-user can request contents◦ Push: Content provider can push the content to

one or more end-users

9/21

System overview –Pull & Push contents

When mobile end-user can request contents◦ Contents Discovery

copies of the same content can be cached in multiple CNF routers in the network

Discover the CNF router with the desired content that is “closest” to the requesting endpoint

10/21

System overview –Pull contents

SContent

Content

• When content provider can push the content Post Office (PO)

Edge of the wired core network Holding and forwarding point for content to mobiles

11/21

System overview –Push contents

PO

1. The sender contacts a name resolution service that resolves the name of the mobile host to a set of PO nodes

2. The sender will forward the file to one or more PO’s using conventional point-to-point routing

3. These PO’s will “hold” the file until contacted by the mobile host to arrange delivery

12/21

System overview –The steps of pushing contents

Each query and content file is carried as a CNF packet data unit or package in a hop-by-hop fashion

13/21

System overview –package

Implemented as overlay network on IP network

14/21

CNF protocol details

A link in the CNF architecture is a logical link between two adjacent CNF nodes

Consists of two components◦ Link Session Protocol (LSP)◦ Link Transport Protocol (LTP)

The choice of LTP will depend on the characteristics of the link

15/21

CNF protocol details –Link layer

Content discovery◦ Content-aware routing based on a content

identifier (CID) Routing content after content was

discovered◦ Conventional (IP) address-based routing

16/21

CNF protocol details –Network layer

Fragment very large files (10’s of GB) into smaller chunks (~100MB-1GB) before transporting

17/21

CNF protocol details –Transport layer

End-host

Name Resolution Service (NRS)◦ Map the name of an endpoint to its

corresponding POs File Name Resolution Service (FNRS)

◦ Map a CID (content identifier) to corresponding attributes of the content Attributes of the content

Content Hash, Content Creator, Content Access Rights, etc

18/21

CNF protocol details –NRS & FNRS

19/21

Conceptual Flow Diagram

Simulation by using ns2 Hop-by-hop vs. TCP performance

◦ TCP is better than hop-by-hop in low load◦ Hop-by-hop is better than TCP in high load

Wireless multi-hop performance◦ The results show that significant throughput gains

are possible with customized link layer protocols like CLAP instead of TCP

Content routing gains◦ Reduction of content retrieval time and traffic

load

20/21

Performance summary

New approach to network design in response to growing needs for improved support for both mobility and content in the future internet

The design presented here is clearly preliminary and will be further refined

21/21

Conclusion