3-3 TCP-HTTP Acceleration SE

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Acceleration & Spoofing with SkyEdge

Name and title of the presenter, Date

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TCP impairments over Satellite links

3-way-handshake to set a connection (3 satellite hops) - hosts constantly

open and tear TCP connections

Multiple TCP connections reduce efficiency because of contention

‘Slow start’ inefficiency (starting with a small window size)

Flow control ‘sliding window’ mechanism (limited maximum rate)

Congestion Avoidance inefficiencies (Each loss regarded as congestion)

Spurious retransmissions (retransmissions caused by long delay, when

no actual packet loss occurred)

TCP/IP headers are a high overhead, especially for small packets such

as ACKs and real-time traffic

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HTTP performance over Satellite links

a single HTML page usually initiates multiple HTTP requests

Each HTML page also initiates a new TCP connections

Hosts spend a long time waiting for TCP links to be established

While waiting, the satellite resources go underutilized

Each HTML page is comprised of multiple objects, each retrieved

separately – satellite delay is a major factor in bad HTTP performance

TCP

HTTP

IP

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SkyEdge Enhancements – TCP spoofingembedded solution

TCP packets are locally acknowledged by the VSAT and hub, respectively

Backbone tunnel:

A single backbone tunnel multiplexes TCP connections efficiently over the satellite

resource (eliminating contention and improving efficiency)

TCP/IP headers are compressed (improving efficiency)

Flow control is handled by the backbone tunnel (overcoming slow start, sliding

window, spurious retransmissions)

The implementation is transparent to the Hosts

20% - 80% improvement and better user experience20% - 80% improvement and better user experience

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Test Case: TCP Spoofing

Reduction in number of Packets (5M IB file)

TCP

Spoofing

TCP

Spoofing No Spoofing

No Spoofing

01,000

2,0003,000

4,0005,000

6,0007,000

8,000

OutboundInbound

Reduction in number of Packets (5M OB file)

TCP

Spoofing

TCP

Spoofing

No Spoofing

No Spoofing

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

OutboundInbound

95% reduction in number of packets !

Downloading 5MB file Uploading 5MB file

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SkyEdge HTTP Optimizationsimplified diagram

HTTP request

HTTP request

time

Browser RPA on VSAT IPA in hub WEB server

Reduce inbound

traffic

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SkyEdge Enhancements – HTTP acceleration

Internet

HubIPA Server

(proxy, load balancer)

Persistent LinkVSAT

Multiple links

Multiple TCP links

Transparent mode: Packets to the internet maintain the original source IP from the VSAT

Transparent Proxy mode: No configuration required on browser

Source=A Dest=B

IP packet

IP Add=A

IP Add=B

Source=A Dest=B

IP packet

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HTTP Acceleration - Principles

Totally transparent to the customer – no configuration required

HTTP acceleration by

One connection from VSAT to Hub versus many from PC to Website

Two tiered cache and pre-fetching of web-elements

Prefetching from the Internet to the hub

Prefetching from the hub cache to the VSAT

Reducing number of required end-to-end handshakes

DNS caching in the VSAT

Implementation principles

Simple installation

Scalable solution

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Reduction in number of Bytes

IPA5.0

No IPA

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Inbound

Reduction in number of Packets

IPA5.0

IPA5.0

No IPA

No IPA

0

5,000

10,000

15,000

20,000

25,000

OutboundInbound

Test Case: HTTP Acceleration

65% 35%

Browsing to WEB site

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HTTP Acceleration – VALUE

increasing link efficiency by ‘HTTP tunneling’ – the VSAT opens a single,

persistent connection to the IPA server after the first object request is received.

Element ‘Pre-fetching’ - reduces the number of object requests that are traveling

over the satellite link and hence - reduces overhead transmission. In addition it

increases the user experience

Up to 90% less traffic –

less packets and bytes on OB,

far less packets on Inbound, far less bytes on inbound

Far better user experience

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Summary

TCP and HTTP acceleration are mandatory for good user

experience and improve network efficiency

SkyEdge’s TCP and HTTP acceleration are the cutting-

edge in optimization solutions:

Improve user experience, thus increasing customer

satisfaction

Improve efficiency and reduce traffic, thus reducing the

cost of the space segment

Reduce IB traffic, thus enable improved QoS for other

(non-TCP/IP) applications

Gilat’s TCP and HTTP acceleration is a comprehensive

solution, scalable , and embedded in SkyEdge VSATs

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