Slow WAN Performance is a Growing Business Challenge
It seems like only a few years ago that we were using analogue and ISDN dial-up connections for internet access and remote access. How things have changed; we all take fast, "always on" internet access for granted. And the availability of inexpensive Firewall/VPN appliances from suppliers like SonicWALL mean that any company which can afford two offices can afford a VPN connection between them and Mobile VPN access for their users while out of the office. And all the time these connections are getting faster and more widely available. If you had predicted today's technologies, speeds and prices 10 years ago, it would have sounded like nirvana. But guess what? We are not satisfied! This is nowhere more the case than among CAD users in the construction industry and other markets. The growth of 2D and 3D CAD data, the growth of visualisation, and the growth of digital photography have led to an explosion in volumes of data and individual file sizes. Whilst this does not cause a problem for users accessing data over a LAN, there has been a parallel growth in the need to share data across extended design teams spread across multiple locations.Users have no interest in the reasons why a WAN is slower than a LAN, and will complain vociferously about slow access to data. This is especially the case with users who roam between offices; who one day are in the office where the data resides and the next day accessing the same data remotely. For them, the performance difference is manifestly clear.
There might seem to be an obvious answer to a slow WAN connection; to buy more bandwidth. But increased bandwidth will not necessarily provide the anticipated performance improvement due to the hidden WAN performance killer - latency. Latency means the inbuilt delay in a system. In the context of a LAN or WAN, latency means the round trip delay between some data being requested and it being returned. Unfortunately computer networks don't work like plumbing systems. When you request a file from a server it is not like a tap being turned on and the data being transferred at full speed until completely transferred. In order to ensure that computer networks work reliably even when there is a lot of traffic, servers send a limited amount of data then wait for the receiving system to confirm that it has arrived. Once that happens then some more is sent. These "here is some data", "OK, I have received it", "here is some more data", stop-start transfers magnify the effect of latency many times over. The congestion-control incurred delays coupled with further queuing and processing delays accumulate to create noticeably slow WAN performance. And unfortunately increasing WAN bandwidth has little impact on them.
Managing Branch Office IT is a Growing Business
Challenge
Another challenge that has arisen with the growth of mass-computerisation is managing branch office IT. The majority of companies working out of more than on location have a large head office and one or more smaller branch offices, with IT staff concentrated in the head office. Branch office IT may be dealt with by
with Riverbed
How this revolutionary technology is improving WAN performance.
By Alex Dewar, Head of IT & IM Solutions, Excitech Ltd.
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Volume 4, Issue 4periodic visits, remotely, or delegated to a non-IT professional based in the branch office.
This leads to challenges and risks with regard to managing, securing and backing-up branch office data. In the absence of IT team members in the branch office, the diligence with which data is backed up may be less than that at the head office. To deal with these challenges there are various measures which business managers and IT departments may want to consider:
● Consolidate back-ups so that back-up tape drives and software in
the head office and branch offices are backed-up over the WAN.
● Enhance High Availability and Disaster Recovery capabilities by
implementing products like Double-Take to replicate servers in real time, so that offices can act as Disaster Recovery partners for each other.
● Set up branch and site offices quickly and inexpensively without the
cost of server hardware, Windows Server, Exchange Server, Tape drive and back-up software, etc.
Riverbed can help with all of these requirements!
Position Riverbed
This is where Riverbed comes in with their Steelhead family of WAN Acceleration products. Riverbed’s goal is to make the experience of working on a WAN as close as possible to working on a LAN. Riverbed are acknowledged market leaders in WAN Acceleration. For
the second year running they have been acknowledged by analysts Gartner as leaders in their WAN Acceleration Magic Quadrant. This means that both in terms of Completeness of Vision and Ability to Execute, Riverbed are ahead of all of their competitors.
Recognition and Customers
Riverbed is an established supplier in this market and has sold tens of thousands of Steelhead Appliances worldwide. Steelhead appliances are used in all market segments, in all regions worldwide, and in companies ranging from SMBs (small to medium sized businesses) to multi-national corporations.
Here is what some companies have said about Riverbed:
“Our files and data now move more than 70 times faster between offices, giving us the ability to complete projects more quickly. We’ve also reduced our WAN traffic overall by 75%.” – Gensler Architecture.
“Riverbed was able to optimize our bandwidth capacity by more than 3 times, and the back-up and recovery window was reduced by 98%, reducing 4 hour back-ups to just 5 minutes.” – Little Diversified Consulting
“Riverbed Appliances are being successfully used by companies sharing large Revit building information models – allowing disparate workers to more easily collaborate on a building project.” – Autodesk
How Riverbed works
Riverbed Steelhead products are available as hardware appliances and as mobile software; Steelhead Mobile is discussed later. To use Riverbed Steelhead appliances you need one at each end of the WAN link to be optimised. They can sit between the LAN and the firewall, or in larger installations a router may be used to route traffic through the Steelhead. They automatically detect each other’s presence and immediately start to optimise the traffic which passes between them. And crucially they are transparent; they require no client or server re-configuration and no agent installation. Riverbed believe that in order to effectively address WAN performance issues, the three main causes all need to be addressed, these are:
●Bandwidth Limitations ●Transport Protocol Chattiness ●Application Protocol Inefficiencies
If you only deal with one of them then all that will happen is that the next bottleneck will become apparent and only a modest performance improvement will be achieved.
Riverbed’s approach is to deal with all of these causes of slow WAN performance with the counter-measures below:
Cause of WAN Slowness Riverbed Feature
Bandwidth Limitations Data Streamlining Transport Protocol Chattiness
and Latency Transport Streamlining
Application Protocol Chattiness
Data Streamlining
Data Streamlining is the technology which people most usually associate with Riverbed. All the data passing over a Riverbed optimised link is broken down into small chunks and stored in a data store on each Steelhead end with a reference. If the sending Steelhead ever sees the same data again instead of re-sending the data it sends the reference thus greatly reducing the volume of traffic transmitted. So, only changed or new data is transmitted over the WAN, and even that new data is sent compressed. This is much more efficient at reducing WAN traffic than old-fashioned file caching. When a file is edited it may be that only a small portion is changed so the Steelheads continue to offer a performance improvement. The beauty of this approach is that it does not matter if a file is opened or copied from Windows Explorer, opened from an application or opened from an email; even if it has been re-named, the bit patterns it contains are the same so Riverbed will optimise the traffic. Riverbed Data Streamlining allows much better use to be made of the available WAN bandwidth because it can reduce WAN traffic by 60-90%.
Transport Streamlining
As described earlier, sending data over a TCP/IP network is not like turning on a tap. There are numerous round trips and delays inherent in TCP/IP network traffic and Riverbed utilises two main techniques to overcome these TCP protocol inefficiencies.
The first is to re-size the TCP Window. The TCP Window is the amount of data which the sending system will transmit without receiving an acknowledgement. Re-sizing the TCP Window means significantly fewer delays while the server waits for client acknowledgement. Second, Riverbed re-packages the TCP "payload" with a combination of compressed new data and references to previously stored data in a technique called Virtual Window Expansion to create virtual Windows of 1MB and over compared to typical TCP Windows of 16KB. These two Transport Streamlining techniques combined can lead to a net reduction in round trips of 60-98%.
Application Streamlining
Riverbed Steelhead has been designed to be application-independent and will optimise all traffic over a TCP/IP WAN. But there are certain applications which Riverbed recognises are particularly important and provide direct application optimisation for. These are applications which are both widely used and inefficient. This Application Streamlining provides performance improvement over-and-above Riverbed's Data and Transport Streamlining.
These applications which are directly accelerated are:
Without Riverbed the chatty nature of these application protocols exacerbates the delays caused by limited bandwidth and TCP Protocol inefficiencies. Riverbed has invested a great deal of time in understanding the traffic between client and server when, for example, a user opens a file from a server share, or when a user starts Microsoft Outlook. These communications are predictable so ripe for optimisation. Using two techniques Riverbed offers significant acceleration of these application protocols. These two techniques are Transparent Pre-population and Transaction Prediction.
Transaction Prediction means the head office Steelhead appears to the server as the client and the client-side Steelhead appears to the client as the server. All the application protocol chattiness is contained on the two LANs and Riverbed optimised traffic passes between the two Steelheads.
Transparent Pre-population means that after a client starts to open a file, the server-side Steelhead continues to request and receive subsequent packets of data before the client has requested them. And also, in the case of the MAPI protocol, when a user closes down their Outlook session the client-side Riverbed keeps the server connection open so that as new emails arrive in their inbox the contents are updated on the client-side Steelhead ready for when the user next logs in.
Protocol Application
CIFS Windows File Sharing
NFS Unix File Sharing
MAPI Exchange Server to Outlook
HTTP & HTTPS Web and Secure Web
Applications
MS-SQL and Oracle Database Driven Applications Backup and Replication Simplified replication of remote
servers.
WAN
Data Centre Remote Office
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Volume 4, Issue 4Steelhead Mobile
In addition to the Riverbed Steelhead appliances which are available in sizes to suit all businesses, Riverbed also have a Steelhead Mobile solution. The way that this works is that the head office runs a Steelhead appliance and a Steelhead Mobile Controller. Then Steelhead Mobile software would be installed on roaming PCs so that when they are out of the office their connection to head office servers would be optimised. The Steelhead Mobile software is derived from the RiOS operating system that runs the Steelhead appliances and offers similar exceptional performance. It is ideal for two scenarios; firstly, home or mobile users making mobile connections to their office files and mailboxes, and secondly, in very small offices you might chose to install the Steelhead Mobile software on each PC instead of purchasing a Steelhead appliance.
CAD Specifics
Riverbed accelerates all WAN traffic but DPJ users will want to know how well it works with CAD data.
Testing Method:
All trials were performed on a live network between two offices, each with a 2Mb leased line internet connection. And where possible, all tests were done with the Riverbed off, cold, warm and a test performed against a local server for comparison.
In this context “cold” means that the Steelheads have never seen the data before so there are no Data Streamlining benefits, but we still see performance improvements as a result of Transport and Application Streamlining. “Warm” means that the Steelheads have seen the data before so we are seeing the full Riverbed benefit.
This is what we have found:
9.8MB AutoCAD 2004 DWG:
9.2MB 2007 DWG Files (same files as above but saved in 2007 DWG format):
2007 DWG with X-refs, same file as above split into three DWG files, each of 5.9MB:
AutoCAD Conclusions
With release 2007 Autodesk optimised the file format to make it more compact and stable. But paradoxically this makes it harder for Riverbed because when the file is saved the bit patterns within it change extensively compared to the 2004 file format. So the warm times to save a 2007 file are not as fast as a 2004 file. However, warm opens and re-opens offer really significant performance increases and genuinely approach the speed of working from a local server. Splitting the 9.2MB file into three and X-referencing them, even through the sum of the three split files was 17.7MB was much faster because only one file was open for editing so only one file got saved back to the server.
For many companies it will not be realistic to standardise on the 2004 DWG file format in order to enjoy better Riverbed optimisation. But using the 2007 DWG file format, especially when files are split into multiple X-refs (which is recommended practice on large projects and in design teams), Riverbed still offers significant performance improvements.
Revit
Revit 2008, 14MB, Opened from server, no Worksets: No
Riverbed
Cold Warm Local
Server
Open 1m 50s 1m 30s 24s 21s
Save 2m 30s 2m 25s 1m 53s 1m 35s
Re-open 1m 30s 24s 24s 20s
No Riverbed
Cold Warm Local
Server
Open 1m 25s 1m 45s 24s 20s
Save 1m 25s 2m 20s 2m 14s 18s
Re-open 1m 20s 18s 18s 18s
No Riverbed
Cold Warm Local
Server
Open 2m 3s 20s 19s 19s
Save 1m 10s 1m 45s 1m 36s 9s
Re-open 2m 0s 20s 19s 18s
No Riverbed Warm
Open Central File 1m 52s 1m 27s
Revit 2008, 32MB, with Worksets:
Revit Conclusions
Clearly with Revit there are significant savings to me made when saving models and saving to central servers. Even in Save to Central operations which by their very nature involve primarily new data which the Steelhead appliances will not have seen before, Riverbed offers significant performance improvements.
Other Benchmark results
Other applications show significant performance improvements using Riverbed, here are some examples of further Excitech tests:
15.5MB Excel 2007 Spreadsheet:
6.8MB Word 2007 Document:
5.6MB PowerPoint 2007 Presentation:
2.0MB Acrobat File:
15.4MB AVI:
CRM System:
Conclusion
Riverbed offers the opportunity to significantly improve the performance of both site-to-site and remote user VPN connections. For companies struggling to work productively over slow broadband connections, Riverbed offers a cost-effective and viable alternative to massive increases in WAN bandwidth.
For more information about Riverbed please see the Excitech web site at www.excitech.co.uk/dpj447.
No Riverbed Warm Local
Open Central File 4m 04s 55s 51s
Copy Central File to Local
3m 26s 10s 7s
Save to Central 2m 32s 24s 17s
No Riverbed
Cold Warm Local
Server
Open 3m 55s 50s 5s 5s
Save 5m 35s 43s 21s 20s
Re-open 4m 0s 6s 7s 6s
No Riverbed
Cold Warm Local
Server
Open 1m 25s 40s 5s 4s
Save 1m 45s 7s 7s 5s
Re-open 1m 55s 6s 7s 4s
No Riverbed
Cold Warm Local
Server
Open 1m 20s 33s 7s 5s
Save 1m 20s 10s 8s 8s
Re-open 1m 10s 6s 7s 5s
No Riverbed
Cold Warm Local
Server
Open 8s 13s 3s 2s
No Riverbed
Cold Warm Local
Server
Open 1m 15s 35s 3s 3s
No Riverbed
Cold Warm
Local Database 32s 21s 19s
Find Record 15s 12s 4s
Create Quote 3s 3s 2s
For more information, see inside back cover 4418 or to ask a question, email: [email protected]
