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7K and Fabric Extender Connectivity



1st question) If I have two 7k switches the connection would be something like this diagram for making a single domain,

what will happen if I have a 3rd 7k and I still want a single domain, should I connect the both 7ks to the new one?



2nd question) I just want to know if I got the concept right? when we have a single domain, it means all ports whether they are FEX ports or 7K switches ports they are all belong to a same logical switch? so all we have to do is to define vlans, and advertise the whole fabric(domain) SVIs to the ospf for them to be connected to the next campus/major network. am I right?

this probably is so much faster, than traditional networks where we connect all switches together from the access layer all the way to core with L3 links, and they are all individual switches.


You wont be able to add in another 7K to the vpc domain, you wont be allowed to create an addtional peer link.
When you create a VPC domain, you are logically creating one switch but there is still the notion of two control planes, they are synced between the two using CFS protocol. Because of this you still need to configure both devices with the same configuration, ie vlans, SVIs and port channels.

But we would have a better performance in compare to two 7Ks that had been setup outside of the domain with L3 links, right? basically what I am asking is that Switches that are connected with CFS Protocol have a better performance in compare to Switches that are connected with L3 links.


and ofc when they are inside of the domain there is no spanning tree running between the switches on the domain from the administrator perspective?!


Can someone help me with my question?

I am still looking for an answer


Sorry I got your message but I can't answer that I have not tested cfs in that aspect based against a standard 7K FEX setup 


If no one has answered it here its best to try TAC they may be able to give you the breakdown of pros and cons of both styles of 


There very different styles of deployment though , one basically allows inter domain communication between 5s/7s and even MDS 9000s but the standard setup is very fixed so getting a test that may work on both to show difference of speeds may be difficult but if anyone has that information it will be Cisco themselves