Date post: | 10-Apr-2015 |
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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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