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05-16-2018 03:29 AM - edited 03-08-2019 03:02 PM
Hi Guys, I need some help.
How can I configure two switches so that a single device with two NICs can plug into both of them in an active/standby or load balance team without creating a loop?
Is it possible to test using packet tracer?
Attached is the image of what I'm trying to achieve.
Two switches connect together and one server with two NICs connected to both switches
Thank you for your help
Claudio
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05-16-2018 03:38 AM - edited 05-16-2018 03:40 AM
Dear Claudio,
You cant do this with packet tacer, in realtime if you need to achieve this in simple catalyst switch like 3750 you need to do stacking . If its nexus or catalyst 6500 series you can achieve it through vPC { Nexus}or VSS { In catalyst}
HTH
Sandy
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05-16-2018 05:42 AM - edited 05-16-2018 05:45 AM
Usually NIC-teaming comprises of three IP addresses, two for physical NICs and one for virtual NIC. They are all in the same subnet. Virtual is the only address that all communication is carrried on.
From STP point of view, server ports are host ports on the switch....so no change in topology.
If the server supports LACP you can configure LACP on switch side too. Alternately, you can simply configure port-channel [802.3ad] on switch.
Regards.

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05-16-2018 03:38 AM - edited 05-16-2018 03:40 AM
Dear Claudio,
You cant do this with packet tacer, in realtime if you need to achieve this in simple catalyst switch like 3750 you need to do stacking . If its nexus or catalyst 6500 series you can achieve it through vPC { Nexus}or VSS { In catalyst}
HTH
Sandy
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05-16-2018 04:24 AM
Hi Sandy,
Thank you for your reply, I will have to read more about it.
This is one of the questions I will have to answer for a job interview, I need to know how to configure the switches. Do you know any software or application that can help me with that?
Thank you
Regards
Cláudio
@SANTHOSHKUMAR SARAVANAN wrote:
Dear Claudio,
You cant do this with packet tacer, in realtime if you need to achieve this in simple catalyst switch like 3750 you need to do stacking . If its nexus or catalyst 6500 series you can achieve it through vPC { Nexus}or VSS { In catalyst}
HTH
Sandy
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05-16-2018 04:17 AM
Active/Active Mode
Switches are not aware that different interfaces on the server comprise a team. Instead, all the teaming logic is done exclusively on the server.In an active/active mode, traffic is spread across both NICs until a failure occurs.
Active/Standby mode
all the traffic is on one team member until a failure occurs. When a failure is detected all the traffic moves to the standby team member.
If you have STP in place it should block loops however to be safe do not put both NICs on the same subnet
The real tradeoff is what happens when there is a failure. If you’ve configured active/standby then you will have the same level of performance in a failure condition whereas you’ll have degraded performace if you go with the active/active mode. On the other hand, when you don’t have a failure, you’ll have much greater bandwidth using active/active.
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05-16-2018 04:49 AM
Hi Jean,
Thank you for your help.
For what I could understand from your explanation, I only have to configure the STP on my switch, the rest (NIC team) is done on the server, correct?
Probably this is a stupid question, but if each nic is on a different subnet and I lost connectivity with one, how the packets will be redirected to the other subnet?
Thank you Jean,
Cláudio
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05-16-2018 05:42 AM - edited 05-16-2018 05:45 AM
Usually NIC-teaming comprises of three IP addresses, two for physical NICs and one for virtual NIC. They are all in the same subnet. Virtual is the only address that all communication is carrried on.
From STP point of view, server ports are host ports on the switch....so no change in topology.
If the server supports LACP you can configure LACP on switch side too. Alternately, you can simply configure port-channel [802.3ad] on switch.
Regards.
