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.


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.


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.


Community Search:
MacTech Search:

Software Updates via MacUpdate

Mellel 4.1.0 - The word processor for sc...
Mellel is the leading word processor for OS X and has been widely considered the industry standard for long form documents since its inception. Mellel focuses on writers and scholars for technical... Read more
ScreenFlow 7.3 - Create screen recording...
ScreenFlow is powerful, easy-to-use screencasting software for the Mac. With ScreenFlow you can record the contents of your entire monitor while also capturing your video camera, microphone and your... Read more
Dashlane 5.9.0 - Password manager and se...
Dashlane is an award-winning service that revolutionizes the online experience by replacing the drudgery of everyday transactional processes with convenient, automated simplicity - in other words,... Read more
ForkLift 3.2 - Powerful file manager: FT...
ForkLift is a powerful file manager and ferociously fast FTP client clothed in a clean and versatile UI that offers the combination of absolute simplicity and raw power expected from a well-executed... Read more
Cocktail 11.5 - General maintenance and...
Cocktail is a general purpose utility for macOS that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Hazel 4.2.4 - Create rules for organizin...
Hazel is your personal housekeeper, organizing and cleaning folders based on rules you define. Hazel can also manage your trash and uninstall your applications. Organize your files using a familiar... Read more
Skype - Voice-over-internet pho...
Skype allows you to talk to friends, family, and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
Backup and Sync 3.40.8921.5350 - File ba...
Backup and Sync (was Google Drive) is a place where you can create, share, collaborate, and keep all of your stuff. Whether you're working with a friend on a joint research project, planning a... Read more
Dashlane 5.9.0 - Password manager and se...
Dashlane is an award-winning service that revolutionizes the online experience by replacing the drudgery of everyday transactional processes with convenient, automated simplicity - in other words,... Read more
Cocktail 11.5 - General maintenance and...
Cocktail is a general purpose utility for macOS that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more

Latest Forum Discussions

See All

How PUBG, Fortnite, and the battle royal...
The history of the battle royale genre isn't a long one. While the nascent parts of the experience have existed ever since players first started killing one another online, it's really only in the past six years that the genre has coalesced into... | Read more »
Around the Empire: What have you missed...
Oh hi nice reader, and thanks for popping in to check out our weekly round-up of all the stuff that you might have missed across the Steel Media network. Yeah, that's right, it's a big ol' network. Obviously 148Apps is the best, but there are some... | Read more »
All the best games on sale for iPhone an...
It might not have been the greatest week for new releases on the App Store, but don't let that get you down, because there are some truly incredible games on sale for iPhone and iPad right now. Seriously, you could buy anything on this list and I... | Read more »
Everything You Need to Know About The Fo...
In just over a week, Epic Games has made a flurry of announcements. First, they revealed that Fortnite—their ultra-popular PUBG competitor—is coming to mobile. This was followed by brief sign-up period for interested beta testers before sending out... | Read more »
The best games that came out for iPhone...
It's not been the best week for games on the App Store. There are a few decent ones here and there, but nothing that's really going to make you throw down what you're doing and run to the nearest WiFi hotspot in order to download it. That's not to... | Read more »
Death Coming (Games)
Death Coming Device: iOS Universal Category: Games Price: $1.99, Version: (iTunes) Description: --- Background Story ---You Died. Pure and simple, but death was not the end. You have become an agent of Death: a... | Read more »
Hints, tips, and tricks for Empires and...
Empires and Puzzles is a slick match-stuff RPG that mixes in a bunch of city-building aspects to keep things fresh. And it's currently the Game of the Day over on the App Store. So, if you're picking it up for the first time today, we thought it'd... | Read more »
What You Need to Know About Sam Barlow’s...
Sam Barlow’s follow up to Her Story is #WarGames, an interactive video series that reimagines the 1983 film WarGames in a more present day context. It’s not exactly a game, but it’s definitely still interesting. Here are the top things you should... | Read more »
Pixel Plex Guide - How to Build Better T...
Pixel Plex is the latest city builder that has come to the App Store, and it takes a pretty different tact than the ones that came before it. Instead of being in charge of your own city by yourself, you have to work together with other players to... | Read more »
Fortnite Will Be Better Than PUBG on Mob...
Before last week, if you asked me which game I prefer between Fortnite Battle Royale and PlayerUnknown’s Battlegrounds (PUBG), I’d choose the latter just about 100% of the time. Now that we know that both games are primed to hit our mobile screens... | Read more »

Price Scanner via

Back in stock: 13-inch 2.5GHz MacBook Pro (Ce...
Apple has Certified Refurbished 13″ 2.5GHz MacBook Pros (MD101LL/A) available for $829, or $270 off original MSRP. Apple’s one-year warranty is standard, and shipping is free: – 13″ 2.5GHz MacBook... Read more
Apple restocks Certified Refurbished 2017 13″...
Apple has Certified Refurbished 2017 13″ MacBook Airs available starting at $849. An Apple one-year warranty is included with each MacBook, and shipping is free: – 13″ 1.8GHz/8GB/128GB MacBook Air (... Read more
8-Core iMac Pro on sale for $4699, save $300
Amazon has the 8-core iMac Pro on sale for $4699 including free shipping. Their price is $300 off MSRP, and it’s the currently lowest price available for an iMac Pro. For the latest up-to-date prices... Read more
10″ 512GB WiFi iPad Pros on sale for $849, sa...
B&H Photo has Space Gray and Rose Gold 10.5″ 512GB WiFi iPad Pros on sale for $849. Their price is $150 off MSRP, and it’s the lowest price available for these models, new, from any Apple... Read more
MacBook Pro sale! B&H drops prices on new...
B&H Photo has dropped prices on new 2017 13″ MacBook Pros, with models now on sale for up to $200 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only. Their... Read more
13″ MacBook Airs on sale for $100-$150 off MS...
B&H Photo has 13″ MacBook Airs on sale for $100-$150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13″ 1.8GHz/128GB MacBook Air (MQD32LL/A): $899, $... Read more
Huge iMac sale! Apple reseller now offering 2...
B&H Photo has new 2017 21″ & 27″ iMacs on sale today for up to $300 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27″ 3.8GHz iMac (MNED2LL/A): $... Read more
Sale! 1.4GHz Mac mini for $399, $100 off MSRP
B&H Photo has the 1.4GHz Mac mini on sale for $399 for a limited time. Their price is $100 off MSRP, and it’s the lowest price available for a mini from any Apple reseller: – 1.4GHz Mac mini (... Read more
Sale of the year continues as Apple resellers...
Adorama has new 2017 15″ MacBook Pros on sale for $250-$300 off MSRP. Shipping is free, and Adorama charges sales tax in NJ and NY only: – 15″ 2.8GHz Touch Bar MacBook Pro Space Gray (MPTR2LL/A): $... Read more
iPad sale continues! 9″ WiFi iPads for $50-$8...
Walmart has 9.7″ Apple iPads on sale for $50-$80 off MSRP for a limited time. Sale prices are for online orders only, in-store prices may vary: – 9″ 32GB iPad: $249.99 $80 off – 9″ 128GB iPad: $379 $... Read more

Jobs Board

*Apple* Retail Sales Associate / Service Wri...
Job DescriptioniStore is the premier retailer of Apple products and solutions. We're looking for dedicated individuals with a passion to simplify and enhance the Read more
Integration Technician, *Apple* - Zones, In...
…adapted, and grown for over 30 years. Position Overview The Apple Integration Technician will be responsible for performing customer specific configuration Read more
*Apple* Retail - Multiple Positions - Apple,...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Part Time Reseller Specialist - *Ap...
…in a reseller store, you help create the energy and excitement around Apple products, providing the right solutions and getting products into customers' hands. You Read more
*Apple* Technical Specialist - Apple, Inc. (...
…customers purchase our products, you're the one who helps them get more out of their new Apple technology. Your day in the Apple Store is filled with a range of Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.