Comments for My EtherealMind

Comment on Is OpenFlow Open ? I Ask – Compared to What ? by Is OpenFlow Losing Its Openness? Part Two.

Is OpenFlow Losing Its Openness? Part Two. — Tue, 28 Feb 2012 08:02:15 +0000

[...] Ferro in his blog post Is OpenFlow Open ? I Ask – Compared to What ? asks the question, “What is the concept of [...]

Comment on A Rolling Upgrade Strategy, Apple OSX and Cloud Infrastructure by Grumpy

Grumpy — Mon, 27 Feb 2012 21:52:00 +0000

I believer that you’re quite right in that legacy or “old stuff” isn’t part of Apple’s plan, but neither is the “enterprise”, they might have achieved a lot more penetration, but most of that has been high end executives that just need^H want a fancy laptop and don’t run key applications, or small businesses where they don’t have any legacy applications…

More application will be updated over time, but it seems that some of these are now been driven by OS availability rather than a business need for the application to be changed, is this cost viable if you have OS upgrades happening every 12 months?

Comment on Merchant Silicon and Vendor Software – The Hype in 2012 by Network, Interrupted

Network, Interrupted — Mon, 27 Feb 2012 17:31:07 +0000

[...] what little vendor silicon is left these days in network gear since Broadcom and the likes seem to be in every vendor’s equipment. Tell me what happens when we put a broadcom chip right on the server bus and OpenFlow becomes a [...]

Comment on Comment: John Chambers on Why Cisco Never Bought Skype — GigaOm by rovinguser

rovinguser — Mon, 27 Feb 2012 16:14:00 +0000

Microsoft has learned it’s lessons : it’s not about hardware, it’s about the services. Expect Windows Phones from every vendor to be packed with skype : OTT telco 2.0 the nightmare of every telco (including it’s suppliers, i.e. Cisco and others). Internet access will be given away by the Amazons, Googles and Apples and startups like Macheen…

Comment on Comment: John Chambers on Why Cisco Never Bought Skype — GigaOm by ccie24290

ccie24290 — Mon, 27 Feb 2012 14:18:00 +0000

I was gutted when Cisco took on Jabber IM and killed it. They would have done the same with Skype. I hate M$ way more than most borg merchants but they’ve not changed Skype much yet…I’ll wait before I criticise JC for missing this one, it could be a lucky break. IMHO Cisco should concentrate far more on making their excellent comms product more inclusive and less proprietary. Businesses like to talk, bedroom dwellers like to type. One tool to rule them all?

Comment on Spanning Tree, Three States & Why Committees Can Suck by Aries

Aries — Mon, 27 Feb 2012 06:14:00 +0000

Super like this write-up. I always wondered this myself, but for once my thinking is correct. They are unnecessarily wasting 15 seconds of valuable time in listening / learning.

Comment on EIGRP – Auto Summary by Dhana Kaneshayogan

Dhana Kaneshayogan — Sun, 26 Feb 2012 09:30:00 +0000

No surprises here. A router will only auto-summarise routes that it knows it can be the “classful” boundary for. Hence, if a router has a 10.x.x.x/24 addressed interface participating in EIGRP, then it will advertise it as a 10.0.0.0/8 to its neighbours.

It wont summarise routes learned from other routers.

Comment on Is OpenFlow Open ? I Ask – Compared to What ? by Peter Ashwood-smith

Peter Ashwood-smith — Thu, 23 Feb 2012 22:20:00 +0000

Greg, very interesting, thanks .. three points. First, the interface between the control plane and the forwarding plane is probably one of the more difficult parts of a switch or router, there is a large volume of ‘stuff ‘ that moves back and forth. So some serious thoughts as to how to optimize that interface will be required in any open version of that interface. Second, since a controller can only control so many devices, controller to controller protocols are required .. the logical choice for those protocols are IETF link state/BGP (at least as a start otherwise .. micro flow based route propagation?) etc. The third thing that has always bothered me is the chicken egg issue of who controls the forwarding between the controller and its devices since clearly we can’t have hundreds of point to point links. That underlying control protocol is going to govern the performance of the entire system and has to be bullet proof because the last thing you want is to ‘brick’ your device by mis configuring forwarding to it from the controller by the controller and then getting permanently stuck.

Comment on What Is the Definition of a Switch Fabric ? by Qfabirc and its role in the enterprise « CCIE 31104, what's next?

Qfabirc and its role in the enterprise « CCIE 31104, what's next? — Thu, 23 Feb 2012 18:14:58 +0000

[...] http://etherealmind.com/what-is-the-definition-of-switch-fabric/ [...]

Comment on Blessay: Autonegotiation on Ethernet – It Works, It Should Be Mandatory! by Oliverg94

Oliverg94 — Wed, 22 Feb 2012 11:45:00 +0000

not tech savy but on xbox media centre it mismatches and i need to change my duplex speed… but my atheros 9285 doesn’t even allow me to…

Comment on A Rolling Upgrade Strategy, Apple OSX and Cloud Infrastructure by Charlie Clemmer

Charlie Clemmer — Wed, 22 Feb 2012 04:42:00 +0000

One thing I expect to see in play here is Apple push that they control the environment. Like the old mantra of limited hardware support in a controlled environment as it relates to OSX, I expect we’ll see further strengthening as Apple attempts to merge OSX and iOS into one environment … ultimately with the same kind of app control on OSX (or the traditional Mac platform after they drop that name) as they’ve established on the iOS mobile devices. The Gatekeeper functionality that’s been announced in OSX 10.8 could be viewed as another step to keep non-Apple approved applications from running, depending on the administrative control provided to that functionality.

Comment on Poster: Cloud Kittens by Kcraycraft

Kcraycraft — Wed, 22 Feb 2012 02:51:00 +0000

Greg where I’d you find all of those kittens?,, a few may be a good mouser.

Comment on EIGRP – Auto Summary by Vedburtruba

Vedburtruba — Mon, 20 Feb 2012 10:26:00 +0000

Route table in last case seems to be absolutely the same as in previous case and there is no 10/8 summary route.

Comment on IOS: Reverse SSH Console Access by Arunmozhi G

Arunmozhi G — Mon, 20 Feb 2012 02:39:00 +0000

Hi Greg,
Useful post.

I have a Cisco 2921 connected to the console ports of different devices(servers,storage switches, N5ks etc. ). I have a loopback ip configured on the router and then I have configured the hosts on the router. So when I want to connect to the storage switch I will type the hostname and enter and it will connect me to that host. So, my question is, is there a way to connect to the console port of the devices straight away from outside using just one command with just the line number and how ?.

Thanks
Arun

Comment on EIGRP – Auto Summary by Gareth Chalk

Gareth Chalk — Mon, 20 Feb 2012 01:01:00 +0000

Shouldnt there be 2 10./8 routes on R3 if auto summary is disabled on R2?

Comment on Tech Notes: Juniper QFabric – A Perspective on Scaling Up by Mjkantowski

Mjkantowski — Sun, 19 Feb 2012 16:09:00 +0000

1. I don’t think the failure domain is that big. You can lose a whole interconnect and still survive with 1/2 the bandwidth capacity (increased oversubscription, in reality.) This is similar to losing one side of your VPC. And if you scale your QFabric out with four interconnect chassis, then you are only looking at 1/4 capacity loss in a failure. Looking at more failures, such as a top of rack QFX3500, obviously that behaves the same way in almost any set up. Then there are things like the directors that can fail, but those are at least clustered into an Active/Active pair. Fabric/read card failures in the interconnect chassis are similar to failures on other vendor’s gear. It’s a decrease in fabric capacity between interconnect chassis front line cards. Front line card failures take out a portion of your capacity for any QFX3500s that are attached to the failed line card. Then there are the 2x EX4200 virtual chassis that are set up for MGMT plane and control plane, respectively. I guess losing an EX4200 that was handling the control plane work for a set of QFX3500s is one of the worst failures you can have. The MGMT plan connections would still be up (they are wired to a completely separate EX4200 VC….though these VC’s are connected to each other which brings up that next question..) I wonder if those surviving MGMT links to the QFX3500s can be used for control plane too in such a failure?

2. What do you mean by point of management? Every node has a MGMT interface plugged into the EX4200 virtual chassis. As far as points of MGMT that you have, once you have it set up, it really seems like the only thing you need to deal with is the director. Of course, there are things like the virtual chassis for MGMT and control plane that I don’t think fall under the director. So I guess you have those to deal with, separately. But even that looks like just 2 switches since it’s VC.

Overall, I think QFabric is highly redundant and beautifully thought out and executed. I haven’t had the chance to operate a deployment, so I’m speaking only about what I’ve read and talked to people about. I would love to get one

Comment on What Is the Definition of a Switch Fabric ? by Joe Smith

Joe Smith — Sun, 19 Feb 2012 01:35:00 +0000

Hello. Interesting article.

I want to reiterate Steve’s question. How does a Crossbar fabric prevent collisions? It doesnt in and of itself, correct? Fabric arbitration, buffers and other methods to prevent HOL are really what prevent the collisions. No?

Thanks

Comment on Tech Notes: Juniper QFabric – A Perspective on Scaling Up by Mjkantowski

Mjkantowski — Sat, 18 Feb 2012 03:24:00 +0000

Yes, you are right on.

Comment on When Proprietary Kills the Standard by it’s with great sadness and reservation I take these powers…. « kontrolissues

it’s with great sadness and reservation I take these powers…. « kontrolissues — Sat, 18 Feb 2012 03:12:50 +0000

[...] with their own agendas, allowing them to force or stall individual projects on a whim. ( see Greg Ferro’s article for a great description of this in [...]

Comment on Tech Notes: Juniper QFabric – A Perspective on Scaling Up by Mjkantowski

Mjkantowski — Sat, 18 Feb 2012 00:20:00 +0000

Don’t forget to watch the Juniper free web based training on installing and configuring QFabric. I couldn’t figure out how to give a good link, but your path is this:

Learning Portal Home > Training Courses > QFabric Switch Installation and Initial Configuration-WBT

So click “Education” off the main homepage, then “Courses”, then use the pulldowns to select product category “Switching” and product family “QFabric”.

Comment on Problems With Cat6A Cables in Data Center by lordbrayam

lordbrayam — Fri, 17 Feb 2012 21:06:00 +0000

Great post !

Comment on Tech Notes: Juniper QFabric – A Perspective on Scaling Up by Lukas Krattiger

Lukas Krattiger — Fri, 17 Feb 2012 19:05:00 +0000

By looking at QFabric, I’m seeing a lot of components involved which is building a whole fabric. Comparing this to a classic Chassis approach does lack a bit as within QFabric, some components are also Chassis based systems.
Even if the N5k/N2k approach is based on a tagging protocol (VNTAG) it would be more comparable to it, not only from a port-count perspective.
Looking at both approaches, two questions are coming into my mind:
1. Do I really want such a big failure domain?
2. How many point of management do I have?

Comment on Tech Notes: Juniper QFabric – A Perspective on Scaling Up by Brandon Bennett

Brandon Bennett — Fri, 17 Feb 2012 15:49:00 +0000

For the “Service Provider” only agrument. If you look at past Juniper product lanches. The MX and the SRX the largest box in the line was launched first and then scaled down. For the SRX this went from a 120Gbps firewall down to a 700Mbit firewall in the size of half a paper.

Qfabric is still new and it will be scaled down for more appropriate deployments. Also although QFabric is often represented as the entire date center and you will get the most benefit from a wide deployment of Qfabric there is NO reason why you have to rip and replace. You can start by buying the QFX3500s (QF/Nodes as standone) and hooking them up to your existing core. At some point it may make sense to buy a couple interconnects and a couple of directors. Maybe later you replace your DC core with QFabric.

For those who think that QFabric still doesn’t fit well or isn;t “ITILable” enough the EX line with VC is still a perfectly valid and great data center design that will look more like existing deployments.

Comment on Tech Notes: Juniper QFabric – A Perspective on Scaling Up by Brandon Bennett

Brandon Bennett — Fri, 17 Feb 2012 15:44:00 +0000

Juniper mantra. Seperation of control plane and forwarding plane as much as possible although It would be nice if the management network could be built into the QF/Interconnect or better yet the QF/Directory for smaller scale networks.

Comment on Tech Notes: Juniper QFabric – A Perspective on Scaling Up by Brandon Bennett

Brandon Bennett — Fri, 17 Feb 2012 15:42:00 +0000

Just like how each linecard in a 6500 actually runs it’s own scaled down version of IOS and they communicate over an internal switch to program thing like FIBs?

Is a Chassis switch or router not a single control plane? How about FEX, Stackwise+, Virtual Chassis. Are these a single control plane?

Distributed control plane would be more appropriate and thats how just about any technology achieves scale. The QF/Directors are still in charge.