High server availability

Unanswered Question
Feb 16th, 2010

Hi all,

I need to achieve an high availability for all the servers having only two NICs belonging to different VLANs with a particular configuration.

Infact, these servers are connected as shows at following:

(VLAN1) -->Server1--> (VLAN2) -->Server2 --> (VLAN3)-->Server3-->(VLAN4)

When one server fails, for example, Server2, the sequence has to be:


How do I achieve that by a swiitch?

Thank you in advance.

Best regards,


I have this problem too.
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Reza Sharifi Tue, 02/16/2010 - 17:22

Hello Giuseppe,

This is possible if you are using 3750 stacked switches or 6500 with VSS. You need to do NIC teaming on your servers and etherchannel on the switches.  This will give you NIC redundancy and also switch redundancy. Also run LACP on your etherchannel



gpangallo Wed, 02/17/2010 - 06:29

Hi Reza,

thank you for your answer. It is a good solution but I have only two NICs where in one of these the traffic flows inbound, for example, on VLAN 1 and in egress on the other NIC belonging to another VLAN, for example, VLAN 2.

Now, we have 4-5 server configured in this fashion. When a server fails I need to preserve the sequence of the traffic flow so it is continuous.

I have to know I could implement the dynamic VLAN replacement so I could preserve the right traffic flow.

The NICs are particular cards that work only at level 2 (MAC address).

I hope I explain correctly and if you have an idea I will be glad.





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