TweetFollow Us on Twitter

MacTech Magazine Article Archives

Volume Number: 23 (2007)
Issue Number: 01
Column Tag: Network Administration

Jumbo Frame Networks

Tap into extra Ethernet speed

By Steve Modica

Approximately one year ago, Apple introduced its first dual Ethernet G5 PowerMac. The system sported an internal Broadcom chip that provided the user with two high-speed Gigabit Ethernet ports.

Why would Apple include a second Ethernet port on their new PowerMac systems? One reason (probably the most obvious) is for Xsan support. To add a system to an Xsan storage network (or almost any clustered filesystem network), the system must be connected to the Fibre Channel based storage, its normal internet connection, and a dedicated "Meta-data" network.

On the previous generation of PowerMacs, this would require the customer to purchase an extra Gigabit Ethernet NIC (network interface card), which uses up one PCIX or PCIE slot and requires the user to open up the machine to install the device. When you consider the extra Fibre Channel card (which may have been ordered directly from Apple), you're now down to one free PCI slot to house your high-speed video capture or other application specific devices.

Given the minimal price premium for going to a dual port Gigabit Chip from a single port, adding that second connector was a no-brainer for Apple.

Xsan and clustered filesystems in general, have a lot of promise. Systems can be attached directly to the shared storage using Fibre Channel, and the Ethernet based "meta-data" network is used as the traffic cop. It assures that multiple systems aren't modifying the same filesystem structures simultaneously.

The problem with these new filesystem technologies is the entry point cost. Purchasing an Apple XRAID is quite economical given their cost per byte ratio (one of the lowest in the industry), but when you add in the cost of a Fibre Channel switch, Fibre Channel adapters for each machine, additional Ethernet ports for the meta-data network and the software licenses, the cost begins to approach $30,000 for even the smallest network. When compared to even high-end NAS storage devices, the choice is easy.

So assuming you are one of the many 5-10 system shops that simply can't justify a $30,000 entry point for storage, but you've paid for all of these great PowerMac and Mac Pro systems with second Gigabit Ethernet ports, what can you do to take advantage of them? There's nothing worse than buying something and leaving it sit idle, especially when shared network performance is one of the most common complaints at small shops.

One very common use of these extra ports is to create a dedicated storage network that uses Gigabit Ethernet's built-in "jumbo frame" technology to speed up the transfer of data, while reducing the amount of cpu overhead created when transferring that data.

A configuration like this can significantly improve network performance for file-transfers, captures and downloads, while freeing the "normal" office network for things like email, web browsing and DHCP services. This setup will also increase the amount of CPU cycles available on the server and the clients for local image processing -- a big win for everyone in the office.

What are Jumbo Frames? Seven years ago, when Gigabit Ethernet was just becoming available, processors were a lot slower than they are today. Vendors weren't crowing about how many Ghz their systems were clocked at. They were still working on hitting the 1Ghz mark! These new "high-speed" Gigabit adapters were expensive and quirky. Finding adapters (which typically ran $1500 or more) that worked with all your platforms and a switch that worked with all your adapters was no small task.

During this period, a typical Gigabit Ethernet adapter would easily eat up an entire CPU just for interrupt processing. It was rare to see a Gigabit adapter perform at "line rate" (IE 1 Gb). More typically, adapters would get between 400 and 600Mbits/sec. This is still plenty good, but it must be remembered that while maintaining these rates, your machine wasn't doing anything else.

Enter the notion of "Jumbo Frames"

Ethernet (and all of its add-on features) are defined as IEEE 802.3. This spec includes things like auto-negotiation, link aggregation, 10MbEthernet, 100Mb/Ethernet and even 10Gb/Ethernet. The spec defines the size of an Ethernet frame as 1500 bytes -- typically somewhere between 1488 and 1514 bytes depending on the platform.

Receiving 1 billion bits of data adds up to 83,333 packets per second. Theoretically, each one of these packets requires the CPU to stop what its doing, receive the packet from the Gigabit card, process the headers, and provide the data to the waiting application (you).

At 83,333 packets per second, most of the CPUs time is spent context switching. It's constantly saving and recalling what it was doing just prior to processing your last packet. No real work is getting done.

Vendors quickly realized that unless they wanted to wait for processor and bus speeds to catch up, they wouldn't sell many cards. They needed a solution that would allow their products to work on the slower processors available at that time. Jumbo frames provided one such solution.

Rather than moving data in 1500 byte chunks, they allowed their cards to use much larger packets. Some vendors supported 16384 bytes, others supported smaller numbers. The "de facto" standard was 9000 bytes.

At 9000 bytes per frame, the packet processing load is reduced by a factor of 6 (13,888 packets per second). The CPU has 1/6th the number of headers to process and theoretically, 1/6th the number of interrupts to handle.

Today, all but the very cheapest switches support jumbo frames and switch ports for Gigabit are well under $100 per port. This makes it extremely easy and economical to create a dedicated jumbo frame network.

Benefits

1. Having a separate network means less bandwidth contention for critical operations like captures or online editing.

2. Jumbo frames allow local systems to have more CPU cycles available for things like Final Cut Pro, improving the users experience running the application.

3. A jumbo frame network can support a larger class of systems including Apple Macbook, Macbook Pros, Mac Minis and iMacs.

4. Jumbo frames can be used to access "storage over Ethernet" devices like iSCSI and AoE RAIDS, such as those designed by companies like 2 Degrees Frost. These products eliminate typical bottlenecks found in client/server networks.

Conclusion

Having extra Gigabit ports on your machines makes using jumbo frames easier than ever and the benefits are tremendous. All small video capture and post houses, audio and pre-press shops should consider this simple, elegant solution to improve their network without breaking the bank.


Steve Modica is the Chief Technical Officer of Small Tree Communications. Mr. Modica brings over 15 years of experience in the field of high performance operating systems to the company. Prior to founding STC, he worked at Silicon Graphics Inc. managing a group of device driver engineers and managing third party vendor relationships. For the four years prior to joining SGI, he owned and operated HPC Consulting; a company specialized in customizing corporate networks. Mr. Modica attended Wayne State University in Detroit on a Merit Scholarship and received his degree in Electrical Engineering in 1992.

 
AAPL
$96.32
Apple Inc.
-1.83
MSFT
$43.17
Microsoft Corpora
-0.41
GOOG
$578.29
Google Inc.
-9.13

MacTech Search:
Community Search:

Software Updates via MacUpdate

OmniPlan 2.3.6 - Robust project manageme...
With OmniPlan, you can create logical, manageable project plans with Gantt charts, schedules, summaries, milestones, and critical paths. Break down the tasks needed to make your project a success,... Read more
Command-C 1.1.1 - Clipboard sharing tool...
Command-C is a revolutionary app which makes easy to share your clipboard between iOS and OS X using your local WiFi network, even if the app is not currently opened. Copy anything (text, pictures,... Read more
Knock 1.1.7 - Unlock your Mac by knockin...
Knock is a faster, safer way to sign in. You keep your iPhone with you all the time. Now you can use it as a password. You never have to open the app -- just knock on your phone twice, even when it's... Read more
Mellel 3.3.6 - Powerful word processor w...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
LibreOffice 4.3.0.4 - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
Freeway Pro 7.0 - Drag-and-drop Web desi...
Freeway Pro lets you build websites with speed and precision... without writing a line of code! With it's user-oriented drag-and-drop interface, Freeway Pro helps you piece together the website of... Read more
Drive Genius 3.2.4 - Powerful system uti...
Drive Genius is an OS X utility designed to provide unsurpassed storage management. Featuring an easy-to-use interface, Drive Genius is packed with powerful tools such as a drive optimizer, a... Read more
Vitamin-R 2.15 - Personal productivity t...
Vitamin-R creates the optimal conditions for your brain to work at its best by structuring your work into short bursts of distraction-free, highly focused activity alternating with opportunities for... Read more
Toast Titanium 12.0 - The ultimate media...
Toast Titanium goes way beyond the very basic burning in the Mac OS and iLife software, and sets the standard for burning CDs, DVDs, and now Blu-ray discs on the Mac. Create superior sounding audio... Read more
OS X Yosemite Wallpaper 1.0 - Desktop im...
OS X Yosemite Wallpaper is the gorgeous new background image for Apple's upcoming OS X 10.10 Yosemite. This wallpaper is available for all screen resolutions with a source file that measures 5,418... Read more

Latest Forum Discussions

See All

Despicable Me: Minion Rush is One Year O...
Despicable Me: Minion Rush is One Year Old, Gets its Biggest Update Yet Posted by Jennifer Allen on July 31st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Plants vs. Zombies 2 Enters the Second H...
Plants vs. Zombies 2 Enters the Second Half of the Dark Ages Posted by Ellis Spice on July 31st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Why Does It Spin? (Games)
Why Does It Spin? 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: THERE'S ONLY ONE RULE: DON'T TOUCH THE WALLS! Do you think you're able to follow this simple rule even if you would have to... | Read more »
Ice Wings Plus (Games)
Ice Wings Plus 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: THE GREAT ENDLESS RUNNER OF COMBAT JETS IS BACK !! With more than 680.000 downloads in the App Store, Ice Wings: Skies of Steel... | Read more »
Murl the Squirrel (Games)
Murl the Squirrel 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Meet Murl. He is teased by a group of flying squirrels because he can't fly. Determined to show them he's can fly, he meets... | Read more »
Celleste (Games)
Celleste 0.1 Device: iOS Universal Category: Games Price: $2.99, Version: 0.1 (iTunes) Description: Lots of cute action with amazing 3D graphics and a new type of gameplay! Take control over the forces of the universe to help a group... | Read more »
Super Heavy Sword (Games)
Super Heavy Sword 0.0.1 Device: iOS Universal Category: Games Price: $.99, Version: 0.0.1 (iTunes) Description: Get Ready to Get HEAVY! Monster Robot Studios presents SUPER Heavy Sword! The sequel to the smash hit HEAVY sword which... | Read more »
Angels In The Sky (Games)
Angels In The Sky 1.00 Device: iOS Universal Category: Games Price: $6.99, Version: 1.00 (iTunes) Description: - A.I.S will only run smoothly on iPhone 5s. It's NOT compatible with iPad, iPhone 5 or earlier devices.- In order to... | Read more »
80 Days (Games)
80 Days 1.0.2 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.2 (iTunes) Description: 1872, with a steampunk twist. Phileas Fogg has wagered he can circumnavigate the world in just eighty days. Choose your own route... | Read more »
Micromon (Games)
Micromon 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: 130+ Animated Monsters to Catch & Battle! No waiting, play at your own pace! Embark on an epic monster capture RPG like none... | Read more »

Price Scanner via MacPrices.net

iPad Cannibalization Threat “Overblown”
Seeking Alpha’s Kevin Greenhalgh observes that while many commentators think Apple’s forthcoming 5.5-inch panel iPhone 6 will cannibalize iPad sales, in his estimation, these concerns are being... Read more
Primate Labs Releases July 2014 MacBook Pro P...
Primate Labs’ John Poole has posted Geekbench 3 results for most of the new MacBook Pro models that Apple released on Tuesday. Poole observes that overall performance improvements for the new MacBook... Read more
Apple Re-Releases Bugfixed MacBook Air EFI Fi...
Apple has posted a bugfixed version EFI Firmware Update 2.9 a for MacBook Air (Mid 2011) models. The update addresses an issue where systems may take longer to wake from sleep than expected, and... Read more
Save $50 on the 2.5GHz Mac mini, plus free sh...
B&H Photo has the 2.5GHz Mac mini on sale for $549.99 including free shipping. That’s $50 off MSRP, and B&H will also include a free copy of Parallels Desktop software. NY sales tax only. Read more
Save up to $140 on an iPad Air with Apple ref...
Apple is offering Certified Refurbished iPad Airs for up to $140 off MSRP. Apple’s one-year warranty is included with each model, and shipping is free. Stock tends to come and go with some of these... Read more
$250 price drop on leftover 15-inch Retina Ma...
B&H Photo has dropped prices on 2013 15″ Retina MacBook Pros by $250 off original MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.3GHz Retina MacBook Pro: $2249, $250 off... Read more
More iPad Upgrade Musings – The ‘Book Mystiqu...
Much discussed recently, what with Apple reporting iPad sales shrinkage over two consecutive quarters, is that it had apparently been widely assumed that tablet users would follow a two-year hardware... Read more
13-inch 2.5GHz MacBook Pro on sale for $999,...
Best Buy has the 13″ 2.5GHz MacBook Pro available for $999.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $100 off MSRP. Price is... Read more
Save up to $300 on an iMac with Apple refurbi...
The Apple Store has Apple Certified Refurbished iMacs available for up to $300 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free. These are the best prices on... Read more
WaterField Unveils 15″ Outback Solo & 13″...
Hard on the heels of Apple’s refreshed MacBook Pro Retina laptops announcement, WaterField Designs has unveiled a 15-inch version of the waxed-canvas and leather Outback Solo and a 13-inch version of... Read more

Jobs Board

Sr. Product Leader, *Apple* Store Apps - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
Sr Software Lead Engineer, *Apple* Online S...
Sr Software Lead Engineer, Apple Online Store Publishing Systems Keywords: Company: Apple Job Code: E3PCAK8MgYYkw Location (City or ZIP): Santa Clara Status: Full Read more
Sr Software Lead Engineer, *Apple* Online S...
Sr Software Lead Engineer, Apple Online Store Publishing Systems Keywords: Company: Apple Job Code: E3PCAK8MgYYkw Location (City or ZIP): Santa Clara Status: Full Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Sr. Product Leader, *Apple* Store Apps - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.