Configuring Dual-homed servers for redundancy to 6509s

[N3t W0rK3r]

I am looking for assitance in properly configuring dual-homed servers for redundancy to two CatOS based 6509s. My search for information on how to do this has been unsuccessful to date, so any help you can provide would be most appreciated.

Do I need any special hardware/software on the 6509s and/or on the servers?

Thanks, in advance.

John

[rsissons]

My understanding is that a server with 2 NICs must have each in its own IP subnet. This means that you would need to use 2 VLANs on the switches and additional hardware/software to route between them. This could be either MFSC cards on the 6500s themselves, or an external router.

[N3t W0rK3r]

That sounds good and makes sense to me, but does that mean that a server connected in this manner will have one dns name that resolves to two different addresses? If so, then how does DNS decide which address to use, and how do the switches and routers decide which interface to forward server-bound traffic? Do you see what I am getting at?

I apologize if this sounds like a stupid question, but I just can't get my head around this.

Thanks very much.

John

[a.awan]

A lot depends on the kind of servers you have and the NIC teaming algorithms they support. Usually two or more NICs can be teamed in either a fault tolerant configuration (with one primary NIC) or in transmit load balancing configuration. Both these configurations allow the NICs to be connected to separate L2 switches so in case your servers do support such kind of teaming all you need is to have both NICs in the same VLAN and ensure L2 connectivity between the Catalyst 6509s. I recommend you research this from the server perspective also and like everything else test it before production deployment.

[N3t W0rK3r]

Atif, thank you for your reply. You have given me just the information I need to continue researching this. The term "nic teaming" is new to me, but I think this is what I was missing.

Thanks again.

John

[a.awan · Accepted solution]

I am glad i could be of some help. Some server makers like HP might have good information on NIC teaming and if you have HP servers you might be in luck :-)

http://h18004.www1.hp.com/products/servers/networking/whitepapers.html

[cckleibeuker]

I am new to NIC teaming.

My question is:

When I use nic teaming for load balancing on two separate L2/L3 switches, how do I configure this on the switches. On one L2/L3 switch it works with an etherchannel.

[AJAZ NAWAZ]

NIC teaming and L/Balancing are two separate technologies. NIC teaming or resilient NIC architecture will protect you from against NIC failure. For loadbalancing look for SLB and CSS.

hth

Ajaz Nawaz

[cckleibeuker]

I just read a document og HP about NIC teaming.

They say that it is possible two load balance on server on twe separated switches.

I have one HP server and two 6506 switches.

HP says to use NIC Team type "802.3ad Dynamic Dual Channel Load Balancing" and that the switches supports 802.3ad. Cisco 6506 support LACP, this is the same as 802.3ad, coorect me if I am wrong.

But my question is how do I have to configure the two 6506 for LACP, so it load balance a server connected to two switches (one VLAN).

Chris

[AJAZ NAWAZ]

John,

I wouldn't suggest that you need any additional HW or SW for the 65k's. The topology used in the deployment will be key and provide you will highly available access to your servers.

If your servers have two nics, you may consider physically attaching one nic to the primary switch and the second to backup switch. Then if both nic's need to see each other span their VLAN between both CAT's. I believe SUN Microsystems IPMP could be used in such design.

hth,

Ajaz Nawaz

[akemp]

I'd agree with anawaz IPMP on Sun , MC Serviceguard on HP/UX, and NIC teaming on Windows.