Configuring vPC

[CiscoBrownBelt]

So if I have a pair of 93k as Core in a vPC domain, and then I have 2 pairs of 9k Access switches that I want to connect to the cores, should I configure these in a vPC domain just as the cores? How do I configure the actual trunk links between them?

[nazimkha]

I am not sure if they are catalyst 9K or Nexus 9K. If the 9K switches can do VSS or vPC then you can have a back to back vPC with a spanned port-channel. if they cannot VSS / vPC then it would be connected as a server. One port-channel per switch

[CiscoBrownBelt]

Yes they are Nexus. So you are saying connect the Core vPC pair and make the downstream 93K access switches another vPC pair the just create a normal Po on both ends to connect them togther?

[raul.hernandez]

It is interesting VPC double sided configuration. I have used succesfully lot of times. The connection between the two N9K layers is done with VPC. Check related section in https://www.cisco.com/c/dam/en/us/products/collateral/switches/nexus-7000-series-switches/C07-572830-00_Agg_Dsgn_Config_DG.PDF

Also search google for "VPC double sided" for more information

Of course, VPC Domain must be different for N9K Access and N9K Core. Also, L3 Routing is forbidden, but I suppose it is not your case.

[CiscoBrownBelt]

Hi thanks. 

L3 routing is forbidded on the access?

So the access are 93k not 92.

I can't open the doc or link - 404

[raul.hernandez]

Trying link again:

https://www.cisco.com/c/dam/en/us/products/collateral/switches/nexus-7000-series-switches/C07-572830-00_Agg_Dsgn_Config_DG.pdf

The routing is nos supported trough VPC connections, when the peer adjacency ends in the Nexus VPC. But I suppose that in an Access topology you don´t need it.

[CiscoBrownBelt]

Do you mind clarifying I am not sure I understand you.So if I have a pair of 95k as Cores in VPC domain 10 and 1 pairs of 93k access switches in different pairs of VPC domains (different numbers on all VPC pairs) just create SVIs on the cores?
What about a management SVI?
If I only have 1 link to use on access switches to connect to cores shall I just configure them as normal trunk?

[raul.hernandez]

Right. You can connect the Cores 95K in VPC Domain 100 and the 93K Access layer in VPC 101, for example. Four (or more) meshed links between both layers assigned to a VPC in each layer.

Over VPC is not supported dynamic routing. So, you have the option that you say, to configure the SVIs in the Core. If you want to configure SVIs in Access-layer you can, but communication with core only is supported with static routing.

Management SVI, if it is the same VLAN in the four chassis is not problema. It is not dynamic routing, is directly L2 connected.

[CiscoBrownBelt]

Ok so I would just configure management SVI on ALL core and access switches.

Just configure a normal trunk between Access and Core switches,

Different VPC domains on ALL pairs correct?

[raul.hernandez]

Right. You can connect the Cores 95K in VPC Domain 100 and the 93K Access layer in VPC  Domain 101, for example. Four (or more) meshed links between both layers assigned to a VPC in each layer.

Over VPC is not supported dynamic routing. So, you have the option that you say, to configure the SVIs in the Core. If you want to configure SVIs in Access-layer you can, but communication with core only is supported with static routing.

Management SVI, if it is the same VLAN in the four chassis is not problem. It is not dynamic routing, is directly L2 connected.

[CiscoBrownBelt]

Ok so I would only put a mgmt SVI on ALL switches, and trunk all switches togther with "switchport mode trunk", no vpc etc. I think I only have the option to do "vpc orphan".

[nazimkha]

Routing over vPC is supported since release 7.0(3)I5(1)

Added support for Layer 3 over vPC.

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/release/notes/70351_nxos_rn.html

For vPC design and best practices you can refer vPC cisco live session :

https://www.ciscolive.com/global/on-demand-library/?search=VPC#/session/14479207929320017eHp