DC design questions

[mikhailov.ivan]

Hello colleagues! There is a question in terms of Data center design. My current customer would like to save a money (often case, right?) and interested in using only 4 nodes in minimal configuration instead of 6. Initially I suggested 2 spines, 2 leafs and 2 bgw\border leafs. They haven't known yet which architecture they will use either ACI or VXLAN-EVPN (NDFC). So they asked could they use only 2 leafs and run all possible roles on it, like standard leafs for endpoint servers plus border leafs for DCI and L3Out at the same time. Let's skip the part of points of failure and performance and by design it isn't recommended and focus focus only on tech.limitations. The question is: can we connect servers and all BGW functions to the same leaf pair at the same time? (servers will use either VPC or VPC fabric with type-4). I remeber that several years ago there was a limit that on BGW we can connect some endpoints like LB, FW etc but only via L3 connection on phy port or sub.int, but we couldn't use SVI for instance. Maybe something has been changes on 2024. I'm still looking for correct design guide for this case. Sorry if the question is too obvious, but I haven't' find the correct answer yet. Thanks!

[mikhailov.ivan]

could anyone help please?

thanks !

[Sergiu.Daniluk · Accepted solution]

Hi @mikhailov.ivan 

In terms of ACI, it's a straight yes - you can use only two leafs for connecting anything to it.

In terms of NXOS VXLAN, if you go for a Multi-Site solution, then you must configure the leafs as VPC BGW - most likely you need VPC on the leafs for server connections, and because on anycast BGW you cannot use SVIs. You have as well the solution to use the Spines as BGW, of course.

Hope it helps,

Sergiu

[mikhailov.ivan]

now it's clear. Thanks mate !