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Quick vPC Question

visitor68
Level 4
Level 4

Need my thinking verified...

If I dual home a device directly into 2 5000 switches in a vpc cluster, I can run active active LAG uplinks, right? But how about if I have that same device uplinked to 2 FEXs which are then uplinked to the same 2 5000 switches in a vpc? Can you still enjoy the functionality of vPC between the 5000s even if youre not directly connected to them? Can you still run act/act LAGs up to the FEXs?

Thanks

20 Replies 20

Reza Sharifi
Hall of Fame
Hall of Fame

Hi,

The FEXs are managed by 5K or 7K devices.  Another word, you have to connect your FEXs to a 5k or a 7k.  A FEX can not operate on its own. It is a fabric extension of 5K or 7K.

HTH

Reza, I know that the FEXs need to be connected to a 5K or 7K.

I still need my questions answered. Thanks

  • But how about if I have that same device uplinked to 2 FEXs which are then uplinked to the same 2 5000 switches in a vpc?

  • Can you still enjoy the functionality of vPC between the 5000s even if youre not directly connected to them?

  • Can you still run act/act LAGs up to the FEXs?

The answer is yes, you can.

Have a look a this link figure-1 and 2 for different scenarios using the FEX with 5K or 7K

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9670/design_guide_c07-625857.pdf

HTH

Thank you, Reza.

I noticed something with you...you give excellent answers to my questions - the second time around, The first time you answer, you write what comes to mind. lol

Thanks

if you want to multihome server links to 2 N2K and the N2K are setup with vPC up to the N5K and you want the servers link to be working in active/active then it is NOT supported now

have a look at the bellow discussion for similar question of yours

i fyou want to have active/active server NICs then multihome it to N2Ks which are connected straight through to N5K ( not vPC toN5K )

https://supportforums.cisco.com/message/3429407

you can also confirm it with cisco by asking the question on the ask the expert runing currently about vPC topic

HTH

if helpful Rate

Marwan,

can you confirm that Active/Active NICs from multihoming servers can be spported To Two N2K or N5K, without having a nother vPC uplink to Two N7K.

So the Scenario is One Server with dual Links connected to Two Nexus 5000 or 7000 , is possible?

Regards,

Mohamed

based on your scenario yes it is supported

the only think is not supported as for now ( i think will be as its mentioned in some Cisco docs you can confirm it with Hatim in the Ask the Expert vPC ) to have multihomed active/active to a N2K witch is vPC up to N5K

for your question it is even possible to have double sided vPC as per the diagram bellow

from N5K to N7K vPC and from N7K to N5K vPC

which is similar to the N2K straight through to N5K and multihomed NICs

HTH

Marwan, I am a bit confused. Sorry.

Can I ask you to kinldy draw diagrams of what IS possible and what is NOT possible? You can use the diagram below and then you can finish it, so to speak. 

Thank you

not a problem

N5K with FEX N2K bellow can be done

the bellow to my knowledge is not supported yet ( confirmed this with Jerry from cisco in the discussion link above ! ) but i think it will be in later software releases

but be aware we are talking about active/active NIC teaming

HTH

Thank you, Marwan.

So, in the top drawing - and specifically in the two scenarios in which a server is dual homed to 2 separate FEXs - the 5000 MUST be part of a vPC domain, correct? Even though the FEXs are straight-through, the 5000s are vPC'ed, so to speak - and that is what allows for the MCEC on the servers, right?

Thanks

Yes, the N5Ks will be in the same vPC domain (same domain ID). You will be able to configure the server with a LACP PO. The config on the N5Ks will be vPC for the 2 ports on different FEXs.

HTH,

jerry

Thank you, Jerry.

Hello Marwan,

Thanks for nice explanation.

this conversation is 5 year old however i found on cisco blog that - "enhanced VPC is still not supported on the Nexus 5010, 5020 or Nexus 7000"

My question arrives on your last diagram (unsupported scenario)

Should i understand that 5 years back eVPC/host VPC was not at all supported on either N7K or N5K with N2K connected down to either of Nexus peer switch where the host/server connected to two N2K running VPC. (active/active NIC teaming) (as you depicted in last diagram) ?

Hi Vinod -

Under current code versions you can only dual home N2Ks to N5500, N5600, and (I think) N6000 switches.  By dual home, I mean connecting a N2K to 2 different parent switches.  You can single home an N2K to any other Nexus switch that supports FEX.

Marwan's last diagram is a supported configuration under current code.  When you build the port-channel for the end host (at the bottom) you will not need the "vpc <#>" command because the nexus already knows based on the FEX connections.

PSC

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