NIC Teaming & MAC learning on Switches

[snarayanaraju]

Hello All - Refer the attached diagram. No LACP or VPC configured in the switches

Question: On which Interface of SWITCH-1 the MAC address of the Windows Server (configured with NIC Teaming) will be learned. In my setup, the MAC f4c9.d3c4.3fd7 is learned alternative between SWITCH-1 Ports Gig 1/5 and Gig 1/6?

If this MAC is learned alternatively (Flapping) between these 2 interfaces of SWITCH-1 does it create issue in network performance to the Server?.

regards,

SAIRAM

[Mark Malone]

Hi
If both of those links are up your going to loop the traffic from the server , one of them should be blocking in STP mode to prevent the loop

can you check is one blocking or else you will have issues
show spanning-tree int g1/1 and repeat the same for 1 , one should be FWD the other BLK

[snarayanaraju]

Hey Mark - In STP perspective, in SWITCH-1 both Gig 1/5 & Gig 1/6 is in DES Role FWD state. I could see the MAC of NIC is changing often between Gig 1/5 & Gig 1/6. This setup is working for many months without major issue, expect a little Request Timeout in Ping test

[Mark Malone]

I would think the timeout could be stp changes in the background
You can confirm with this command , if the timers are resetting then there are layer 2 convergence changes going on in the background whihc would cause momentary loss of packets , depoending how large the network is it can have knock on effects

show spanning-tree detail | inc ieee|occurr|from|is exec

[snarayanaraju]

Thanks Mark - I will check the STP timers. By the way, what is the best practice. Do i have to configure Active/Standby in NIC?. Does LACP is a solution as well?

[snarayanaraju]

Hi Mark - This is the output from SWITCH-1

SWITCH-1#show spanning-tree detail | inc ieee|occurr
Number of topology changes 14318 last change occurred 00:25:44 ago
Number of topology changes 7826 last change occurred 00:25:44 ago
Number of topology changes 8329 last change occurred 00:53:30 ago
SWITCH-1#

[Mark Malone · Accepted solution]

Hi is that constantly resetting , did you run the full command it should show you what interface its originating from

xxxxxxx#show spanning-tree detail | inc ieee|occurr|from|is exec
Number of topology changes 192 last change occurred 2d23h ago
from GigabitEthernet0/1

id also look at the link below that Paul suggested, lacp wont work unless switches are stacked or in vss or vpc mode acting as one unit , you could have 1 active standby interface though stp  by setting cost either

[snarayanaraju]

Thank you Mark.

[paul driver]

Hello

Link state Tracking (LST) is ideal for this -review it here -

res
Paul

[snarayanaraju]

Hey Paul - Thanks for response. I want to know, On which interface of SWITCH-1, the MAC address is learned as both the Links are in STP FWD state. Both the Links are in STP FWD state because the Topology i have given doesnt detect the loop, unless STP is running on the Server NIC. In my case Server NIC doesnt run STP

regards,

sairam

[paul driver]

Hello

the switch runs stp not the server -So  you should be okay providing stp is active for the vlan the teamed nic is attached to.

res

paul