Comments on: A few words about Nexus 7000

By: Felix Rodriguez

Felix Rodriguez — Tue, 04 Jan 2011 09:46:24 +0000

It really isn’t hard at all to get the 7000 within 10 meters of a large population of servers. As long as you have patch panels to each of the rows in a data center it can reach servers as far as 200 feet. The wire management on this 7000 is very organized too.

By: Brad Hedlund

Brad Hedlund — Tue, 30 Nov 2010 02:04:57 +0000

Shahid,
VoQ with Central Arbitration, such as found in the Nexus 7000/5000 and MDS, eliminates head of line blocking (HOLB) and supports lossless switching within the box. If a lossless switch gets congested, it needs to tell its link partners so they can slow down their send rate, to create a lossless network. PFC 802.1Qbb are the messages that a lossless switch sends to its link partner when its input buffers reach a congestion threshold. ETS 802.1Qaz is not a message, it just defines a switch (or network adapter) that can provide minimum bandwidth guarantees to individual classes of traffic.
VoQ and Central Arbitration makes a switch lossless, PFC 802.1Qbb messages are how these switches communicate congestion to each other to form a lossless network.

By: Shahid Shafi

Shahid Shafi — Mon, 29 Nov 2010 21:49:01 +0000

Hi Brad,

Is VoQ applicable for ingress traffic to the switch? I am trying to understand the difference between VOQ and PFC 802.1Qbb/802.1Qaz.

thanks,

By: BG

BG — Fri, 28 Aug 2009 16:47:35 +0000

James, you seem easily amused. However, I am not so confidant that your question was answered to my delight..

Brad, I believe it is a fare assumption that most engineers will conclude that when a port is in a ’shutdown state’ it is using less power than a port actively forwarding data.

However I believe the question was more in line with, if ports are in an up / up state and there is 0% traffic traversing the interface will the NEXUS 7K remove the port from service and place into a Administrative / Down (Shut Down) state without human intervention? Also, in which state is power actually removed from a port?

If yes, would this result in a less (–) power drawl on the line card as a whole, hence power reduction from the power plant?

BTW- I think the Force10 looks like a “Predator on ludes” the NEXUS is much more sleek!
Ref- Comment by Brad Hedlund on 12 January 2009:
James,
Great question! A port that is not transmitting or receiving data is using less power than a port this is operating at full line rate. So, Yes, a port that is ’shutdown’ is using less power than a port actively forwarding data.

By: james hoffman

james hoffman — Sat, 17 Jan 2009 15:13:32 +0000

Brad,
Thanks so much for the quick response I am so glad I found this forum as it is difficult to get quick answers for “real” advanced technology topics. (Even when you know most of the ce and de’s at cisco) currently I am connecting a nexus solution to a wombat ticker feed for low latency I will post an update on how that goes in to coming months. Thanks again this is a great forum!!!!

By: Brad Hedlund

Brad Hedlund — Tue, 13 Jan 2009 05:10:44 +0000

James,
Great question! A port that is not transmitting or receiving data is using less power than a port this is operating at full line rate. So, Yes, a port that is ‘shutdown’ is using less power than a port actively forwarding data. A line card requests a power reservation from the system based on a worst case scenario, the most power it would ever need. However the power reserved by the linecard is not always the power that is actually used at any given time. This is why the Cisco Power Calculator on Cisco.com now shows “Typical Power” for Nexus 7000 configurations, in addition to “Total Power” which represents the worst case scenario. Typical Power is usually 30% less than worst case scenario Total Power due to the efficiencies saved in idle and shutdown ports. For example, the 32-port 10GE lincard reserves 750W from the system but typically only consumes 600W.

I love the enthusiasm for Nexus!

By: James Hoffman

James Hoffman — Mon, 12 Jan 2009 16:02:57 +0000

Brad,
I have been doing a great deal of work around data center consolidation and ultra low latency design. I completely agree with the FACT that the nexus should not even be spoken about in the same sentence as other switch vendors it is truly apples and oranges. This FACT is solidified when you look at technologies like ultra low latency, port cascading, enhanced low latent QOS, and then when you start incorporating ecosystem technologies like DAL and RAB Cisco puts itself in a class of its own. I do have one question however; my customers have been asking me if the Nexus switch will have the ability to power down ports when not in use. I expect to have an answer soon as we will be deploying this product in many of our accounts but for now I have no answer. Can you enlighten me on this topic since power consumption is always a hot topic?

By: Brad Hedlund

Brad Hedlund — Sat, 14 Jun 2008 14:47:08 +0000

Lets not confuse what is possible, with what is practical.

By: Scott Schweitzer

Scott Schweitzer — Fri, 13 Jun 2008 18:52:40 +0000

One could easily do 496 servers with 10M Twinax cables, but using Myricom’s 21U 512-port switch configured with 496 SFP+ 10GbE ports. Six 42U racks on each side of the networking rack all loaded with 1U servers would be a piece of cake.

Given that we also sell a 640-port 21U 10G Edge switch we could configure Twinax between computers and the Edge switches and fiber between Edges and multiple centralized 512-port Core switches the limit of 10M on Twinax is manageable. Actually up to 8,192 computers it’s pretty easy, after that it takes a little thought!

By: Brad Hedlund

Brad Hedlund — Sat, 07 Jun 2008 02:25:54 +0000

Max distance on SFP+ Twinax is 10 meters. It would be difficult to get a large population of servers within 10 meters of a Nexus 7000. Piece of cake with Nexus 5000 however because it is a Top of Rack switch. The majority of deployments where servers are connecting directly to Nexus 7000 will be done via fiber where the Nexus 7000 sits at the end or middle in a row of server cabinets.