implementation and evaluation of a performance enhancing proxy for wireless tcp scenarios and...

Implementation and Evaluation of a Performance Enhancing Proxy for Wireless

TCP

Scenarios and Architecture

Scenarios of interest

Definition Scenario:Every time, hardware changes (including configurations) have to be

done, a new scenario is created.

Meta-Modell for Scenarios

• ??????

Classification

Classify Scenarios in different Classes:

• Wired

• Wireless– Local (fixed IP)– Mobile

• Handover Access Points• Handover Access Techniques

Standard Wired Scenarios

Possible Scenarios:• Server & Client in same net (LAN), client-server-

path known and traffic „stable/static“• Wired World = Internet, Client & Server in

different subnets, path unknown, traffic variable, more congestion

ClientServer

(e.g. HTTP, FTP)

”Wired World”

Fixed wireless Scenario

Possible Scenarios:• Server in same/different subnet as Client• High BER• Signal loss, reconnect

Wired World

WLAN AP Server (e.g. HTTP, FTP)

Mobile Wireless Scenario (Access Points)

Possible Scenarios:• AP‘s same/different subnet• Server & Client same/different subnet

Wired World


WLAN APHandover

Mobile Wireless Scenarios (Access Techniques)

Possible Scenarios:• WLAN -> GPRS -> WLAN• WLAN -> UMTS -> WLAN• WLAN -> Bluetooth -> WLAN• .....

Wired World


GPRS APHandover

Current Network Architecture

IP LAB: Current Architecture

E

A

B

C

DInternet

GPRS

Network

Server (e.g. Video application)

WLAN (802.11)

Wired access(Ethernet)

Cellular access(GPRS)

RouterSwitch

WLAN AP

WLAN AP

WLAN AP

WLAN AP

Router

Router

Router

Router

Meta-modell for Network Architectures

Meta-Network-Modell

TCP ProxyServer

(e.g. HTTP, FTP)

”Wireless World” ”Wired World”

Possible Network Architectures

Classification of Architectures

• Intercepting– In-Path– Router-Config– Gartious ARP

• Forced (Terminologie??)– IP-Tunneling– IP-Header-Modification

Full Intercepting Proxy Network Design

Internet

GPRS

Network

Server (e.g. HTTP, FTP)


A

RouterSwitchWLAN AP 1

WLAN AP 3

B

Router

DRouter

ERouter

C

Router

TCP Proxy

TCP Proxy

TCP Proxy

Intranet

StudNetTerminalWLAN AP 2

Client

SwitchWLAN AP 4

TCP Proxy

Wireless World

Wired World

Possible Scenarios in Full Intercepting

• Server -> Switch -> Client• Server -> Switch -> TCP Proxy -> WLAN

AP 3-> Client• Server -> Switch -> Routers -> Switch ->

TCP Proxy -> WLAN AP 1 -> Client• Server -> Switch -> Routers -> TCP Proxy

-> Internet -> Intranet -> Terminal• Handover WLAN AP 1 -> WLAN AP 2• Handover WLAN AP 2 -> WLAN AP 3• Handover WLAN AP 3 -> WLAN AP 4• Handover WLAN AP -> GPRS

Problems of Full Intercepted Proxy Scenario

• Hardware efforts (4 Proxies) -> reduction to max. 2 proxy PC‘s for handover possible => reconfig for every Scenario needed

• Internal Server access by Port-Forwarding

• How to realize GPRS handover (Server IP change from internal to external IP needed, use Mobile IP??)

Improved Intercepting Proxy Network Design

Internet


GPRS

NetworkCellular access

(GPRS)

A

Router

SwitchWLAN AP 1

WLAN AP 3

B

Router

DRouter

ERouter

C

Router

TCP Proxy

Intranet

StudNetTerminal

WLAN AP 2

Client

Switch

WLAN AP 4

Switch

Switch

Wireless World

Wired World

IMPOSSIBLE

Forced Proxy Scenarios

Internet

GPRS

Network


A


WLAN AP 3

B

Router

DRouter

ERouter

C

Router

Intranet


Client

SwitchWLAN AP 4

TCP Proxy

Wireless World

Wired World

Problems of Forced Proxy Solution

• How to implement forced Proxy? Possible Solutions:– „TCP packet in TCP packet“-solution (IP-

Tunneling)– Modifying TCP packet: Target IP in Optional

field, Proxy IP in Dest. Field

• How to access internal Proxy from outside world (New TCP Proxy protocol on new port + port forwarding)?

• More network traffic, evtl. More hops• GPRS problem not resolved (MobileIP)

Router Config Proxy Scenarios

Internet

GPRS

Network



A


WLAN AP 3

B

Router

DRouter

ERouter

C

Router

Intranet


Client

SwitchWLAN AP 4

TCP Proxy

Wired World

Mixed World

Wireless World

Mixed World

Automated Forced Proxy Network Design

• Idea:– Categorize every port on router in „wireless,

wired, (evtl. Mixed?)“ – Force router to send packets from wireless to

wired over TCP Proxy ( send from Mixed or to Mixed always over TCP proxy)

• Problems:– Is this possible?– How to force WLAN AP 3 & 4 to use Proxy?

Functional Architecture

„Implementation Plan“

Functional Implementation

• Router Config• ARP to catch all packets

Internet

GPRS

Network



WLAN AP 3

DRouter

ERouter

Intranet

StudNetTerminal

Client

Switch

WLAN AP 4TCP Proxy

implementation and evaluation of a performance enhancing proxy for wireless tcp scenarios and...

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