IBM VLAG and Cisco vPC

[anazarenko]

Dear All,

What's your opinion about mixing these two technologies in the same Datacenter. IBM VLAG will be used  mainly on the Blade Centers, and vPC in the access/distribution layers. It's planned to connect IBM VLAG-enabled  switches straight into Nexus 5ks.

My main concern is mixing different vendor loop-avoidance technologies in the same L2 domain. But there're  engineers who are comfortable with that and arguing that in case VLAG falls apart, fallback STP will take care about the network or storm-control on the Access  layer will block the excess traffic.

[anazarenko]

Just for the public information: the integration with IBM VLAG took place  and went quite successfully.

The following design points were chosen:

1)STP is disabled on IBM EN4093 switches. The overall  STP domain should better stay only with Cisco equipment. 

2)b2b vpc-vlag on N5k side has STP as a fallback mechanism. In a Dual-Active IBM scenario this 's a case.

3)LACP link-aggregation.

We conducted a number of different failover tests, including a complete reset of IBM switches to factory defaults and dual-active IBM operation, without any impact on the overall DC network.

[yuji_eda]

Thank you for information.

I have tried the same from N5K to Cumulus Linux in the past.
At this time there was no problem except that LLDP display was not partly done.

I am planning to try the same thing from N9K to VDX now.
Your information became very helpful. If the next plan goes well, I will expand the information.

[Michal Mihaly]

Hello,

can you elaborate on the solution a little bit? How does it work, when you disable STP on the IBM switches while still leave STP as a fallback mechanism in VPC LAPC port-channel? What does the N5K switch think of such links?

- sh spanning-tree interface Poxyz example would be fine as well as some standard VPC/LAPC configuration 

We're now running STP on the IBM 8124s as well on the 4093s. One side of the 8124s is VLAG to the 4093s and the other is VPC to the N5Ks. We do run the STP instance per each vlan on the 8124s and the ports on the N5Ks are configured as standard VPC port-type normal ports. So STP looks something like this (mark that VLAN 671 doesn't have an individual instance on the IBM switch, ergo the N5K switch things its edge port):

N5K_SW1# sh spanning-tree interface port-channel 155

Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0671 Desg FWD 1 128.4250 (vPC) Edge P2p

VLAN0672 Desg FWD 1 128.4250 (vPC) P2p

VLAN0673 Desg FWD 1 128.4250 (vPC) P2p

VLAN0674 Desg FWD 1 128.4250 (vPC) P2p

VLAN0675 Desg FWD 1 128.4250 (vPC) P2p

Thank you in advance for clarification.

The reason is that we plan to remove the 8124s from the topology and connect the 4093 directly to the nexus switches while leaving everything as it is. From what I understood from your description - your approach is different from what we do right now.