User:TK at HU: Difference between revisions

From
Jump to navigation Jump to search
No edit summary
(Split-TCP)
 
Line 2: Line 2:


=== Introduction ===
=== Introduction ===
A protocol concept to improve Data transfer rates over mobile wireless Ad-Hoc networks. "Split-TCP" or "TCP with proxies" was developed at the University of California Riverside and describes the possibility to improve efficiency with more than 2 connections. It reduces the problems of suppression of connectivity and unnecessary efforts in finding new network routes. The protocol is understood as further development of the TCP network protocol. Generally it is a service with proxys installed in the network.
A protocol concept to improve Data transfer rates over mobile wireless Ad-Hoc networks.


⚫
Proxys: are network nodes, a connecting piece, which receive IP-packets from Source and deliver to the destination.
"Split-TCP" or "TCP with proxies" was developed at the University of California Riverside and

describes the possibility to improve efficiency with more than 2 connections. It reduces the

problems of suppression of connectivity and unnecessary efforts in finding new network routes.

The protocol is understood as further development of the TCP network protocol. Generally it is a

service with proxys installed in the network.

⚫
Proxys: are network nodes, a connecting piece, which receive IP-packets from Source and deliver

to the destination.


=== current problems of TCP ===
=== current problems of TCP ===
The nodes devide the data bandwidth into unfair pieces. If more than one connection is
The nodes devide the data bandwidth into unfair pieces. If more than one connection is established at one node, then this connection is preferred, which:

established at one node, then this connection is preferred, which:
# established first
# established first
# sends more data packets per second
# sends more data packets per second
# has a shorter way from source.
# has a shorter way from source.
The effect is a suppression of the first connection, which is as long suppressed as the second
The effect is a suppression of the first connection, which is as long suppressed as the second one delivers packets and use the bandwidth.

one delivers packets and use the bandwidth.


=== How it works ===
=== How it works ===
Line 35: Line 19:
# A packet through a hop is delivered like in a normal TCP-Packet
# A packet through a hop is delivered like in a normal TCP-Packet
# A hop becomes a proxy, when the IP-Packet went through a certain number of hops
# A hop becomes a proxy, when the IP-Packet went through a certain number of hops
# A proxy is a proxy only for one connection. Even when it delivers IP-packet of a second
# A proxy is a proxy only for one connection. Even when it delivers IP-packet of a second connection, it behaves like a normal hop simultanously.

connection, it behaves like a normal hop simultanously.
# A proxy sends a local acknowledgement (LACK) to the previous proxy or source.
# A proxy sends a local acknowledgement (LACK) to the previous proxy or source.
# Another Acknowledgement (ACK) is sent from the destination to the source.
# Another Acknowledgement (ACK) is sent from the destination to the source.
Line 48: Line 30:


=== efficiency ===
=== efficiency ===
It was shown, that an improvement of 10% to 20% data transfer rate is possible. This number
It was shown, that an improvement of 10% to 20% data transfer rate is possible. This number varies with different settings and data traffic.


The Split-TCP protocol specially improves connectivity over network with high mobility.The last proxy connected to a fast mobile nod has to handle the situation, not the source far away.
varies with different settings and data traffic.

The fairness between TCP sessions is given by adjusting the bandwidth fastly.


=== reference ===
=== reference ===
[1] http://www.cs.ucr.edu/~krish/splittcp.pdf, University of California, 19.9.2002
[1] http://www.cs.ucr.edu/~krish/splittcp.pdf, University of California, 19.9.2002


== German ==

=== Einführung ===
Ein Konzept mit dem Datenübertragungsraten bei mobilen wireless Ad-Hoc Netzwerken verbessert werden sollen. "Split-TCP" oder "TCP with proxies" wurde an der Universität von Kalifornien Riverside entwickelt und beschreibt die Möglichkeit mit einem neuen "Split-TCP" Protokoll die Effizienz bei mehreren gleichzeitigen Verbindungen zu verbessern und Problemen wie Verbindungsunterdrückung oder unnötigen Aufwand beim Finden einer neuen Route vorzubeugen. Es versteht sich als Weiterentwicklung von TCP. Grob gesehen funktioniert es so wie bei herkömmlichen Proxys. Das sind Zwischenstationen von denen IP-Pakete weiter zum Empfänger gesendet werden.

=== Funktionsweise ===
Das Protokoll schreibt vor, das nach einer bestimmten Anzahl von Hops (Verbindungsknoten im Ad-Hoc Netzwerk) ein Proxy sich um die Weitergabe des IP-Paketes kümmert.

'''Die Regeln'''

# Paket wird über normale Hops wie beim TCP Protokoll weitergeleitet.
# Ein Hop wird zum Proxy, wenn IP-Paket schon bestimmte Anzahl Hops durchlief
# Ein Proxy ist nur für eine Verbindung Proxy, sonst gleichzeitig normaler Knoten (Hop)
# Ein Proxy schickt lokale Bestätigung (LACK) zurück an vorhergehenden Proxy oder Quelle.
# Der Proxy ist selbst dann für Weitergabe des Datenpaketes verantwortlich
# Die lokale Bestätigung (LACK) wird nur zum Nachbarproxy versendet, nicht weiter.
# Es wird noch eine Bestätigung (ACK) auf die gleiche Weise vom Ziel zur Quelle zurückversendet
'''Regeln zum Puffer'''
# Datenpakete, von allen Verbindungen speichern, die noch nicht bestätigt sind.
# Bestätigungen ACK

Die Bestätigung (ACK) von Quelle zum Ziel ist eine End-2-End Kontrolle, die es so bei dem herkömmlichen TCP auch gibt.


=== Probleme von TCP (herkömmlich) ===
Die Knoten können die Bandbreite von Verbindungen "unfair" aufteilen. Wenn mehrere Verbindung durch einen Knoten gehen, wird die bevorzugt die:
* sich zuerst aufgebaut hat
* mehr Datenpakete durchschickt
* kürzeren Weg zur Quelle hat
Die Wirkung ist eine Unterdrückung von einer 2. Verbindung, die z.B. quer zur 1. Verbindung läuft. Die 2. Verbindung bleibt solange unterbrochen, bis die 1. weniger Datenpackete durchschickt.


=== Effizienz von Split-TCP ===
Es wird ein einer Studie von [1] gezeigt, dass es eine Verbesserung der Performance von rund 10-20 % gibt je nach Auslastung des Netzes und weiteren Faktoren.

=== Referenz ===
[1] "Departmentof Computer Science and Engineering, University of California, Riverside, Riverside, CA,92521"

Latest revision as of 05:04, 28 August 2006

Split-TCP

Introduction

A protocol concept to improve Data transfer rates over mobile wireless Ad-Hoc networks. "Split-TCP" or "TCP with proxies" was developed at the University of California Riverside and describes the possibility to improve efficiency with more than 2 connections. It reduces the problems of suppression of connectivity and unnecessary efforts in finding new network routes. The protocol is understood as further development of the TCP network protocol. Generally it is a service with proxys installed in the network.

Proxys: are network nodes, a connecting piece, which receive IP-packets from Source and deliver to the destination.

current problems of TCP

The nodes devide the data bandwidth into unfair pieces. If more than one connection is established at one node, then this connection is preferred, which:

  1. established first
  2. sends more data packets per second
  3. has a shorter way from source.

The effect is a suppression of the first connection, which is as long suppressed as the second one delivers packets and use the bandwidth.

How it works

The protocol lays down a proxy after a certain number of hops (network nodes).

The rules

  1. A packet through a hop is delivered like in a normal TCP-Packet
  2. A hop becomes a proxy, when the IP-Packet went through a certain number of hops
  3. A proxy is a proxy only for one connection. Even when it delivers IP-packet of a second connection, it behaves like a normal hop simultanously.
  4. A proxy sends a local acknowledgement (LACK) to the previous proxy or source.
  5. Another Acknowledgement (ACK) is sent from the destination to the source.
  6. Even the ACK needs a LACK every proxy.

the buffer

  1. store every data packet of every connection until it is acknowledged with LACK
  2. every ACK until delivered.


efficiency

It was shown, that an improvement of 10% to 20% data transfer rate is possible. This number varies with different settings and data traffic.

The Split-TCP protocol specially improves connectivity over network with high mobility.The last proxy connected to a fast mobile nod has to handle the situation, not the source far away.

The fairness between TCP sessions is given by adjusting the bandwidth fastly.

reference

[1] http://www.cs.ucr.edu/~krish/splittcp.pdf, University of California, 19.9.2002

Retrieved from "https://sarwiki.informatik.hu-berlin.de/index.php?title=User:TK_at_HU&oldid=5863"