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New Member

dual home servers to access-switches

hi all..

I am trying to figure out what I can do when I want to dual home a server NIC to two different access-layer switches.

My design is that I want to use two L3 switches in the distribution whit a L3 between them. My access-layer switches have uplinks to both the distribution switches, but are running L2 trunk. The L2/L3 is in the distr. switches who are running HSRP towards access-layer..

I was hoping to be able to do this with keeping the L3 between distr. sw, not making this a L2.

Will I have to make the NICs in different vlans? on, or do I need to put them in different vlans.. I am trying to figure this out, but need some help..

Today the switches are clustered, and I have the NICs in the same vlan. The plan is to split the cluster... No more cluster... I figure that the NICs will not loadbalance, but working one at a time. I am not a server guy, so I dont know this for sure. I am looking to find a couple of different options here that I would be able to solve this..

anybody that have any experience with this and can help me on the way...?



Re: dual home servers to access-switches


Our servers are dual attached to different switches, but on the same VLAN. Each access layer switch is dual attached to to each distro. Distro is inter-connected via Layer 2 and each distro is layer3 connected to the core. Why do you not want a layer 2 trunk between the distros? IMO HSRP is messy with out the trunk. If you do layer3 at the distro each switch needs to be a vlan, no sharing of vlans in access switches! AFAIK both NIC's need to be in the same VLAN, but I have'nt touched a server in a while and could be wrong. You'll want to double check that. Here's a link that should help.

New Member

Re: dual home servers to access-switches

hi.... using layer 3 between the distr`s is to get things less complex, getting the most destermistic and best performance in terms of convergense, reliability and manageability. But also making sure we are free from L2 loops and making sure STP dont have to resolve convergense ...

We have no need for spanning vlans across the access-switches and from what I have understand, Cisco says that if you can avoid using L2 linke between distr.... Do it..

However, with regards to the requerments I have over here with dual homed servers, I am not sure that this would be posible.. I know that if I make that trunk I am good to go, but I wondered if this was achivable with also using a L3 between them..



Re: dual home servers to access-switches

If your access switches can do layer 3 your OK. Fast convergence and no STP would be nice!

New Member

Re: dual home servers to access-switches

There isn't any easy answer to your question. It all depends on what the server, its OS and its NIC drivers are capable of. It also depends on whether you want the dual-homed NICs to work as an active/standby pair (i.e. failover), or active/active (i.e. load-sharing). You simply have to discuss this with the server support people and get down and dirty with the NIC and OS documentation. If possible, test it all out in a pilot as well.

And then, once you've got it all tied up in a bow, it will work. Until a sys admin installs new NIC drivers, that is...