NX5000 & NX2000 questions

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Jan 8th, 2010
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I am new to the Nexus range and have a couple of questions to ask.

1)   If a NX2k is dual-homed to a pair of NX5Ks, which are joined by a vPC, which NX5K is the 'parent', and can you specify this?

2)   When connecting servers to the NX2Ks, what is the best strategy?  I have seen some Cisco diagrams which have servers using teamed NICs to connect to a pair of NX2Ks, which in turn each connect to a single NX5K.  Both of the NX5Ks are connected by a vPC, and the teamed NIC to NX2K connections is a vPC too

     Also I have seen diagrams, which are similar to the layout in question one: NX2K dual-homed to a pair of NX5Ks.  In this case the servers only connect to a single NX2K.

     So I guess I am asking can you have the following scenario:

     1 server with teamed NICs connecting to two NX2Ks.  Each of the NX2Ks is connected to the same pair of NX5Ks.  vPC is then used between the NX5Ks, between the NX5Ks and the NX2Ks, and also between the NX2Ks and the server?

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johgill Tue, 01/12/2010 - 05:33
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The vPC primary switch will have the role "primary" when you look at "show vpc".  The role is not considered for switching traffic, just for vPC communication.  You can change the vPC system priority and vPC local role priority to change which switch is elected primary.

The last scenario you mentioned would be the best of all worlds, but cannot be done yet, and is why you probably haven't seen it.  This is something that will likely be implemented in the future.

Right now, you can use only these two scenarios:

Single Homed Fabric Extender vPC Topology

Dual Homed Fabric Extender vPC Topology

hsw_networking Wed, 01/13/2010 - 05:43
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Thanks for your response.

With the vPC primary setting, thanks for clarifying that.

Regards the last scenario, just a shame that is not an option.  Hopefully it will be available in the future, like you say.

It all makes it a lot clearer, so I can work with our server guys, to get it all installed.


kesva.naidoo Wed, 09/19/2012 - 15:24
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I have a question regarding the first scenario which we are also implementing, but the 5Ks are also connectted to 7Ks. With VM NIC teaming configured on the servers, can be an active/active configuration on the server? I am confused because one of the 5K is VPC primary and the other VPC secondary, so I am wondering how the server VLANs that are configured on the VPC connected to the server; be in an active/active state.

johgill Wed, 09/19/2012 - 18:29
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I think you are talking about the "best of both worlds" option.  Where you have a vPC in the form of an active-active FEX, and then you have one port from each of two different FEX in a vPC.  This is known as a two-layer vpc, or an enhanced vpc.  When this thread was started, it was not possible. 

Today, we can use EvPC on the 5500 series platform:


If this isn't what you think you are looking to do, let me know.


John Gill

kesva.naidoo Tue, 11/27/2012 - 07:04
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We have decided to single home the NEXUS 2Ks to each 5K. I beleive tha the maximum number of 2Ks per 5K is 12, but apparently in future versions the number is going to increase to 20 per 5K. I also have another question. We intend to connect another set of 2 x 5K and corresponding 24 x 2Ks, 12 to each 5K. What is the best practice to connect this second domian without enabling another VDC, as we have already maxxed out VDCs. How can we extend rechability between the VPC domains?




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