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New Member

Cisco N5K-urgent

hi,

I have 4 x cisco N5K switches, 2 in each site. siwtches in each site are connected via a peer link which is working fine. now I want to connect both sites via 2 x 10G fibers i.e.

switch-1 site-1  to switch-1 site-2

switch-2 site-1 to switch-2 site 2

aand using the following config per switch:

interface port-channel4060

  switchport mode trunk

  spanning-tree port type network

  flowcontrol receive on

  flowcontrol send on

  vpc 4060

interface Ethernet1/24

  description 10G link to TC2NXSW002

  switchport mode trunk

  flowcontrol receive on

  flowcontrol send on

  channel-group 4060 mode active

the same config is on every switch as i am using po4060 and eth1/24 on all the switches.

Can you please have a look if my config is right as its not working?

Many thanks,

Qk

7 REPLIES

Re: Cisco N5K-urgent

Hi,

As this is what would be considered a double-sided vPC, I presume you've configured the vPC domain ID to be different for the switches in both sites? You should have a vPC domain with a unique ID in site 1 comprised of Site1-Switch1 and Site1-Switch2, and then another vPC domain with a different vPC ID used within site 2 comprised of Site2-Switch1 and Site2-Switch2.

Can you post show port-channel summary and show vpc from each of the switches so we can see if there are any errors?

Also, at this point I don't believe it's related to the issue you're seeing, but the use of the spanning-tree port type network command is only recommended on the vPC peer link. I would change this to use spanning-tree port type normal for the links between the sites.

Regards

New Member

Cisco N5K-urgent

thanks Steve for your swift response.

If you mean the vpc id  so I have used vpc 4060 on all the four switches.

but as soon as  I enable the ports. the ports goes into suspended state and when I remove the interfaces from vpc the ports goes up.

any advice please?

regards,

New Member

Cisco N5K-urgent

I have just noticed the vpc domain on all the switches have set to number-1. could this be the problem?

thanks

Purple

Cisco N5K-urgent

   Yes each domain must have a different name , one site could be like domain 10  and the other sight could be 11 , but they must be different.

Re: Cisco N5K-urgent

Hi,

Most certainly that is your problem. As I stated in the original response you should have a unique vPC domain ID for the two switches in site 1, and another unique domain ID for the switches in site 2. This is what is referred to as "Double Sided vPC".

If you take a look at Mark Stinnette's Quick Start Guide :: Virtual Port Channel (vPC) you'll see this shown on slide 4, and in more detail on slide 17. In the example on slide 17 you'll see that the Nexus 7K pair use vpc domain 1, and the Nexus 5K pair use vpc domain 10.

As shown in the note at the top of slide 17, and again on slide 32 "vPC Configuration - Strong Recommendation", Always use different domain ID in double-sided vPC topology.

Regards

New Member

Re: Cisco N5K-urgent

Many thanks Steve and Glen.

However, i have another question. as these switches are  live and down time is really hard to get. is there any way I can change the VPC domain id on eitehr side without dropping the connections?

Also I have left the 2 x new links connected and but removed from the the VPC. They are working and i can see data is going through the new links but

the problem is that both the links are up and I was thinking spanning-tree would block one the links?(any idea?)

I really appreciate your help!

regards,

qasim

Cisco N5K-urgent

Hi Qasim,

Unfortunately not. If you change the vPC domain ID it will flap the peer-link and all vPC member ports.

Regards

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