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Google Global Cache (GGC) Operations for
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Netmanias Tech-Blog Google Global Cache (GGC) Operations for YouTube (Part 1. KT)

1. The KT subscriber enters www.youtube...
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Google Global Cache (GGC) Operations for YouTube (Part 1. KT)

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Google Global Cache (GGC) Operations for YouTube (Part 1. KT)

  1. 1. NETMANIAS TECH-BLOG Please visit www.netmanias.com to view more posts Google Global Cache (GGC) Operations for YouTube (Part 1. KT) April 16, 2012 | By Chris (tech@netmanias.com) | Netmanias Tech-Blog | www.netmanias.com We are going to present you workflow that shows how a YouTube video is downloaded to a subscriber device via Google Global Caches installed in LG U+ IP network. Below, we will look at downloading over the KT IP network, which has no Google Global Cache installed in it. In the subsequent post, downloading procedures in the LG U+ IP network, which has Google Global Caches installed in it, will be discussed using two different cases - on a Cache Hit and on a Cache Miss (i.e. when a Google Global Cache has a video requested and when it does not). YouTube Downloads over the KT IP Network We assumed a network configured as follows for the purposes of this post:  On the grey board in the left [Google Server (USA)]: YouTube server (www.youtube.com) and Google Global Cache (o-o.preferred.lax04t01.v1.lscache6.c.youtube.com) located in US  On the grey board in the right [KT Network (Korea)]: A KT subscriber connected to KT IP network in Korea  On the grey board in the middle [Transit]: Transit network that connects KT IP network to a IP network in US 1 DNS Query www.youtube.com 2 DNS Response 74.125.71.136 4 HTTP GET 3 Click “Avatar” in YouTube page Request Video = Avatar 6 HTTP Response Download Server Hostname = o-o.preferred.lax04t01.v1.lscache6.c.youtube.com 5 Check User IP address: 7 DNS Query If (User IP addr is LG U+ range) Assign “LG U+ Google Cache” else Assign “Google Cache in USA” o-o.preferred.lax04t01.v1.lscache6.c.youtube.com 8 DNS Response 74.125.215.176 9 HTTP GET Request Video = Avatar 10 Video (Avatar) Download RTT = 200ms ... www.youtube.com KT DNS o-o.preferred.lax04t01.v1.lscache6.c.youtube.com PC KT Subscriber Google Cache Google Server (USA) Transit KT Network (Korea) 1
  2. 2. Netmanias Tech-Blog Google Global Cache (GGC) Operations for YouTube (Part 1. KT) 1. The KT subscriber enters www.youtube.com into his browser to access a YouTube server. The subscriber device sends a DNS query to a KT DNS server (the DNS server doesn't have to be a KT DNS server) to obtain the IP address of the YouTube server. 2. The KT DNS server gives the subscriber device the IP address of the YouTube server (i.e. 74.125.71.136). 3. The subscriber accesses the YouTube server and clicks "Avatar" on YouTube. 4. The subscriber device sends a HTTP GET message to the YouTube server to request an Avatar video. 5. This is the most important step of the process. The YouTube server checks the IP address of the subscriber device when it receives the HTTP GET message. This step is to check whether or not the IP address of a device is within the range assigned to an operator who has Google Global Caches installed in its network. In this example, KT has no Google Global Cache in its network. 6. Therefore, the YouTube server gives the hostname of a Google Global Cache located in US (i.e. oo.preferred.lax04t01.v1.lscache6.c.youtube.com) to the subscriber device. 7. The subscriber device performs a DNS query about hostname = oo.preferred.lax04t01.v1.lscache6.c.youtube.com. 8. As a result of the query, the subscriber device receives an IP address of 74.125.215.176, which is the IP address of the Google Global Cache located in US. 9. Now, the subscriber device sends a request for the video to the server at 74.125.215.176. 10. The subscriber downloads the video from the Google Global Cache (presumably located in LA since the hostname has "lax"). The RTT between two countries is very high - about 200 ms. Besides, if there is heavy traffic (e.g. in the evening), buffering will be severe. Severe enough to keep the subscriber from watching the video. 2
  3. 3. Netmanias Research and Consulting Scope 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 eMBMS/Mobile IPTV CDN/Mobile CDN Transparent Caching BSS/OSS Services Cable TPS Voice/Video Quality IMS Policy Control/PCRF IPTV/TPS LTE Mobile Network Mobile WiMAX Carrier WiFi LTE Backaul Data Center Migration Carrier Ethernet FTTH Wireline Network Data Center Metro Ethernet MPLS IP Routing CDN Transparent Caching Analysis Networks eMBMS LTE IMS Infrastructure Services Analyze trends, technologies and market Report Technical documents Blog One-Shot gallery Concept Design DRM POC Training Wi-Fi We design the future protocols IP/MPLS We design the future Carrier Ethernet We design the future Consulting Visit http://www.netmanias.com to view and download more technical documents. Future About NMC Consulting Group (www.netmanias.com) NMC Consulting Group is an advanced and professional network consulting company, specializing in IP network areas (e.g., FTTH, Metro Ethernet and IP/MPLS), service areas (e.g., IPTV, IMS and CDN), and wireless network areas (e.g., Mobile WiMAX, LTE and Wi-Fi) since 2002. Copyright © 2002-2013 NMC Consulting Group. All rights reserved. 3

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