VXLAN spine or SD-Access border on the 9500?

[Gavin Sparks]

Hi,

I've been looking at the SD-Access documentation/webinars and I am a little confused with the overlap with VXLAN. It's stated that the SD-Access is based around VXLAN and that 9500s are supported as Border devices.

However the 9500s are not supported as a VXLAN spine switch in the VXLAN documentation? Isn't the functionality of the border device essentially the same as the Spine device if we take external connectivity out of the equation? Basically the border allows the VXLAN traffic from the VTEP devices to communicate? The VXLAN spine documentation all says Nexus switches only support this functionality. However the SD-WAN documentation matrix says that the Nexus 7k is only for "outside" fabric border functionality.

What am i missing in my understanding of this? If we had 9500 as our Distribution Layer (effectively the leaf and 9500s in the Core (essentially a spine) and wanted to do VXLAN would that work using pure VXLAN with BGP EVPN? Or does the SD-Access add something else? 

Many thanks in advance

[jedolphi]

Hello Gavin, I **suspect** you may have accidentally read some Nexus/ACI documentation. We have Catalyst 9500 (for campus LAN / SD-Access) and we have Nexus 9500 (for ACI / DC).

In SD-Access you can connect fabric edges directly to border switches, or, you can have a multi-hop routed path between fabric edge and border. In SD-Access there is no official concept of "spine", instead it's called "intermediate node". If you have a multi-hop routed path between FE and border then you have an intermediate node between them e.g. BORDER---IN---IN---FE. The IN routes VXLAN packets between fabric edges and borders, or fabric edges and fabric edges. Catalyst 9500 is one of the platforms we would recommend for IN role in an SD-Access network because it brings some additional functionality that compliments/automates SD-Access, but technically speaking, any platform that supports jumbo MTU, IGP and routed ports could be an IN e.g. Cat 6500, ASR, Nexus 7K, Nexus 9500, etc. Hope that makes sense. Jerome

[Mariusz Kazmierski · Accepted solution]

Hi Gavin, 

To add on top of what Jerome mentioned, note that there are two solutions: 

1) SD-Access which creates overlay with LISP (control-plane) and VXLAN (data-plane) and is fully orchestrated via DNA-Center. This solution uses naming convention like: border node, control node, edge node and Cat9500 is supported in this solution. Refer to the white paper for more details: https://www.cisco.com/c/dam/en/us/solutions/collateral/enterprise-networks/software-defined-access/white-paper-c11-740585.pdf

2) VXLAN EVPN which creates overlay with BGP (control-plane) and VXLAN (data-plane). This solution, known from Data Center environments and Nexus world, uses naming convention like spine & leaf. Here Cat9500 is currently not supported as a spine.  Refer to documentation: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/16-12/configuration_guide/vxlan/b_1612_bgp_evpn_vxlan_9500_cg.html

Regards, Mariusz

[Gavin Sparks]

This is the distinction I was struggling with. Thanks

[Gavin Sparks]

Thanks for the timely reply.

The confusion for me has been the control plane i believe. Whether we're doing BGP EVPN of LISP. There is a lot of documentation on both that has confused that matter for me.

I read this article but can see which is referencing Catalyst 9500s however it utilises spine Nexus 7ks and Ebgp

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/16-11/configuration_guide/lyr2/b_1611_lyr2_9500_cg/configuring_vxlan_bgp_evpn.html#id_79182

However another article https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/16-6/configuration_guide/cf/b_166_cf_9500_cg/b_166_cf_9500_cg_chapter_00.html

Has no mention of nexus 9k and uses LISP