Port-channel reducdency in Nexus 9K switches

[chaitu.kranthi]

Hello Team,

We have a typical requirement from business to avoid outage at our datacenter.

For your reference i am attaching a visio about current and future setup planning.

We have man links between our data centers currently 2 X 10 Gig links running on port-channel.

Due to capacity issue we planned to upgrade of these links to 40Gig and now vendor has upgraded one of our Man link to 40 Gig and second one may take more than 4 to 6 months due to recent Covid-19 situation.

Since we have two different speeds now in port channel we are able to use only one link.

Now the business is looking for redundent port channel for an interim period, so the plan is create two port-channels and one will be with 10 gig interface and second port-channel will be with 40Gig. and the expectation is traffic has to route via 40 gig link and 10Gig port-channel should be in standby incase of any failure to 40Gig interface/port-channel traffic to shift automatically to 10gig one.

Can some one sugget possible options

[Sergiu.Daniluk]

Hi @chaitu.kranthi 

As far as I can see, there is no need to use vpc/port-channels as of now, since you only have one 40G and one 10G interfaces on the respective vPC peers. Leave them as individual links, and STP will take care of loop avoidance, best path (40G) selection.

Once the 10G convets to 40G, you will configure port-channel as the current setup.

Regards,

Sergiu

[chaitu.kranthi]

Hi Sergiu,

Thanks for your quick reply..Just want to understand further on this part. Currently our devices are configured with Spanning tree MST. does this config automatically takes care. Also i would like to understand if the 10Gig interface is in suspended mode due to spanning tree and if the 40Gig goes down, will it automatically enables the port ?

spanning-tree mode mst
spanning-tree pathcost method long
spanning-tree port type edge default
spanning-tree port type edge bpduguard default
spanning-tree mst 1 priority 24576
spanning-tree mst configuration

sh spanning-tree mst 1

##### MST1 vlans mapped: 1-3967,4048-4093
Bridge address 00f2.8bfd.4f7f priority 24577 (24576 sysid 1)
Root this switch for MST1

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po1 Desg FWD 250 128.4096 (vPC peer-link) Network P2p
Po50 Desg FWD 200 128.4145 (vPC) Network P2p

[paul driver]

Hello
I would suggest to keep both 10GB & 40GB  port-channels and activate their related physical interfaces as/when applicable, Just remember the more interfaces added decreases the stp cost of that PC, The 40gb should be calculated to have the lower stp cost but you can always manually specify this for a more deterministic stp path..

int port-channel xx
spanning-tree mst x cost xxx