WAN-accelerators, How they work

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1 WAN-accelerators, How they work By: Fred Geerlings Version: 1.0 Date: April 1 st 2015

2 table of contents 1 Introduction IPknowledge Management Summary TCP protocol Latency reduction Data reduction compression Data reduction caching Optimal link utilization (TCP acceleration) Application acceleration CIFS (SMB) (Outlook Exchange) Quality of Service Practice Results Accountancy organisation Dutch Defense Datacenter replication Government organization Riverbed More information

3 1 Introduction This paper provides insight into the operation of the WAN Accelerator. 2 IPknowledge IPknowledge was founded in 2004 by a number of staff of well-known system integrators in the Netherlands. Soon KPMG (one of our 1 st clients) tipped us about WAN accelerators. IPknowledge became in 2004 one of the first Riverbed Partners. IPknowledge is Riverbed Elite Partner and Riverbed Riverbed Professional Services Partner. 3 Management Summary WAN-accelerators optimize traffic by: Eliminating the adverse effects of latency; Data compression; Data caching, even with modified data; Optimimal fill of the Pipe Application acceleration; Quality of Service. More extensive and easier than Routers. Note: The information in this document has been simplified to make it more readable. In practice, the TCP algorithms are more complex. 3

4 4 TCP protocol Almost all networks make use of the TCP/IP protocol. Because the working of the TCP mechanism has an impact on the performance of a network, we will first look into this. When we save a file on a Server, this file is divided into small parts, which we call Packets. Why? TCP/IP is developed in the era of 300Baud modems. When you get some interference during a file transfer, you have to resent the whole file, now you have only to resent the lost Packet. Ethernet Packets are about 1.5Kb in size. Sending a packet from one location to another takes time. This time is called latency. This time is usually expressed in milliseconds (ms). As a rule, regardless of the amount of bandwidth a "file transfer" slows as latency increases. The available bandwidth is not used in many cases because of the limitations of the TCP protocol. 4

5 Note: Latency is often confused with the so-called Round-Trim Time (RTT), the RTT is the time that a packet back and needs back and is generally equal to two times the latency. See Wikipedia for more information. Examples of latency: From To Latency (ms) The Netherlands The Netherlands (fibre optic) 3-5 The Netherlands The Netherlands (copper) The Netherlands US The Netherlands Asia Pacific Satellite link Latency reduction Off course we can t eliminate latency, but we can eliminate the adverse effects of latency. How does that work? WAN-accelerators divide the link into 3 parts: 1. PC WAN-accelerator 2. WAN-accelerator - WAN-accelerator 3. WAN-accelerator Server By modifying the parameters between both WAN-accelerators, there is on the WAN a continuous and uninterrupted flow of packets. A File Transfer will go so much faster because the available bandwidth can be fully utilized. 5

6 6 Data reduction compression A WAN accelerator uses (where possible) compression (like WinZip). This will in the case of Office documents often reaches 2x reduction, allowing a file also loads 2x as fast! 7 Data reduction caching WAN Accelerators cache once transmitted data and provide it with a unique tag (label). When the same file is sent again, the WAN Accelerators sent only the tag. A hunderd Kb File suddenly becomes a label (5 to 8 bytes)! But caching goes further! Each file is divided into two equal parts, both of which also get their own label. These pieces are halved again, which also get their own label. This process continues until the pieces are about 100 to 300 Bytes. Why? Imagine you are working in MS-Word and save a file on the central server. Then it turns out a "d" should be a "t". You change it and save the file again. In this case, only the piece of the file in which the "d / t" is sent again, the rest is a handful of labels'! 6

7 8 Optimal link utilization (TCP acceleration) Because the 'sender' of data (for example, a PC or Server) is not aware about the speed of the network in-between it starts to send data at an average speed. If this goes well, the speed is increased, until it receives a signal (Router: Line-full) that it goes too fast. The speed than is halved, and slowly increased, until it gets again the Line-full signal from the router. The chart below shows: The link speed (Green) Reality (Red) Reality with WAN accelerators (Blue) 7

8 9 Application acceleration Especially chatty applications (applications that ask many questions, for example a server) use a lot of Round Trips FILE WHICH FILE? For international connections the latency is often mS, for satellite connections, this is 500ms or more CIFS (SMB) A good example is the CIFS (or SMB) protocol, Microsoft's standard for almost all networks. With CIFS there are as many as 30 to 70 questions back and forth before the 1st data is sent. At a SatCom link this means 30-70x 600ms, so it takes at least 20 to 40 seconds, before the 1 st packet of data is sent! With WAN accelerators the remote WAN Accelerator acts as the server and ask all questions at the PC with LAN speed and (almost) no latency. The collected answers are sent to the central WAN Accelerator, who now acts as the PC and communicates with the Server (with LAN speed and latency). Already after 1 Roundtrip the 1st data is sent! Your win in case of a Satellite link is 20 to 40 seconds! 8

9 9.2 (Outlook Exchange) Especially global companies are working "follow-the-sun' and therefore receiving around the clock! Suppose your employees work from 09:00 to 17:00 hours. 17:00 When the PC is switched-off, Outlook tells Exchange to hold the until the next morning. 09:00 The PC is turned on again and Outlook is started. Outlook asks for new - , who promptly is sent by the Mail Server. This causes a noticeable peak on the WAN, slowing down other applications. The new also arrives slowly Now with WAN-accelerators: 17:00 When the PC is switched-off, Outlook doesn t tell Exchange to hold the (this signal is blocked by the WAN-accelerator). Incoming is so just sent across the WAN. WAN Accelerators tag (cache) this . Because there is no PC is to receive the incoming , it will be deleted. 09:00 The PC is turned on again and Outlook is started. Outlook asks for the new , which is promptly sent by the Mail Server. Because the central WAN accelerator recognizes the , only the tag is sent. is so much faster within and doesn t cause a peak on the WAN! The above examples (CIFS SMB and Outlook Exchange) are just two examples. Modern WAN Accelerators can recognize and accelerate more than 400 applications! 9

10 10 Quality of Service Many organizations have Quality of Service (QoS) in place to prioritize business critical applications. Configuration is not easy (programming Routers) and needs frequent consultation of the provider. This is in practice often a continuous process because the application-mix changing continuously... WAN accelerators are also capable to handle QoS. Configuration is very simple (GUI) and can be done from a central management console (CMC) and pushed to all locations with just one mouseclick. Many applications use http, which is recognized by a router as port-80 traffic. A router can t distinguish between SAP (with http frontend) and Browsing on the Internet. A WAN-accelerator can, using Deep Packet Inspection (DPI). WAN-accelerators also provides information about QoS. This makes managing of Quality of Service services very simple and clearly so administrators saves time. 10

11 11 Practice Results Some realistic acceleration values:: 11

12 11.1 Accountancy organisation A European leader in the field of accountancy, strong presence in France, Italy, Spain, Belgium and Great Britain. The network in the Netherlands has already been optimized with Riverbed accelerators. The 10Mbps connection to the Headquarters in Paris caused problems. A Proof-of-Concept (PoC) gave 6-8x reduction! 12

13 11.2 Dutch Defense After the Dutch troops left Uruzgan (Afghanistan), the Compounds were taken over by the US Army, including the Welfare connections. In practice, a 20Mbps connection SatCom was accelerated 10 to 15x!, The 20Mbps Satellite links now peaks up to 600Mbps! 13

14 11.3 Datacenter replication This organization creates lasting solutions to the growing demand for scarce resources such as energy and water by striving to care for wellbeing at optimum efficiency. Headquarter is located in Westland. In the east of the Netherlands, they had also had a location. For the replication of the NetApp storage the custome chooses for a 20Mbps KPN-line, in conjunction with WAN accelerators. WAN Accelerators gave them an average 20x reduction, with peaks >100! 14

15 11.4 Government organization This organization registered jobseekers, unplug jobseeker CVs to vacancies and employers through the "exhibition" at the sites and job coaches. Meanwhile, this organization was incorporated into a larger whole. The Office automation of this organization was contracted in 2006 to Atos (then Atos Origin). Because they had long-term contracts for the WAN, Atos Origin asked IPknowledge whether it was possible to use these existing links with WAN accelerators. A PoC has shown that this was possible! Some results: WAN Data MB LAN Data 11.5 GB Total Data Reduction % Over Last Week 92,00% Peak Data Reduction % Over Last Week 98,00% Peak Data Reduction Occurred At :00 Capacity Increase 13.8X Port Reduction LAN WAN Traffic % Total Traffic FTP (21) HTTP (80) CIFS:NetBIOS (139) CIFS:TCP (445) SQL:TDS (1433) MAPI (7830) Other (Optimized) Passed Through (Unoptimized) GB 1.2 GB -- 0,00% 0 Bytes 0 Bytes 0,00% 98,90% 15 MB KB 0,30% 91,20% 61.7 MB 5.4 MB 1,30% 93,30% 2.9 GB MB 66,90% 0,00% 0 Bytes 0 Bytes 0,00% 92,50% MB 17.5 MB 5,30% 91,80% MB 9.6 MB 2,60% 0,00% 1 GB 1 GB 23,30% 15

16 12 Riverbed According to Gartner (and IPknowledge), the US-based company Riverbed is the Market Leader for WANaccelerators: 13 More information

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