NIC Teaming and Link Aggregation in Switch

November 5, 2009 at 07:12:21
Specs: Server 2003, Dual Xeon 5150
I have a rather detailed question about teaming 2 Broadcom 57 series NICS using their Smart Load Balancing and Failover configuration and connecting the physical NICs to two different 3Com switches - grouping the ports in each switch to increase the throughput to the NICs.

Is this a good place for this?



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November 5, 2009 at 07:39:10
You can't go to two different switches. Has to be to one switch that supports one of the teaming protocols.

BTW been doing this for 10 years with hp and nortel switches using a varity of nic manufacturers mostly intel/hp with both copper and fiber.

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November 5, 2009 at 11:31:45
best application for this is using a blade switch and teaming ports across blades. In cisco, its called a port-channel.

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November 9, 2009 at 05:51:52
Thanks guys for your responses. I'm going to lay out my entire confusion for you. Any insight you can offer is appreciated.

As I mentioned I have servers with Broadcom NICs in them. Using Broadcom's software I can team the NICs a number of different ways. I currently have them set up as such:

NIC A connected to Switch A
NIC B connected to Switch B
NIC A and NIC B teamed using Broadcom's Smart Load Balancing and Failover configuration.

My switches are 3Com Baseline 2848 Plus. I understand that these are standalone switches which as you suggested prevents me from being able to create a "group" using ports on Switch A and Switch B.

I think Broadcom's SLB&F are key here. This is what I know about it:

This proprietary Broadcom technology provides fault tolerance and load balancing based on IP flow. This feature can balance IP traffic across as many as eight team members for both outbound and inbound traffic. In this mode, all adapters in the team have separate MAC addresses. Smart Load Balancing™ (SLB) provides automatic fault detection and dynamic failover to another team member or to a hot-standby member, and works with any switch or hub. and

In this type of team, a standby member handles the traffic if all of the load balance members fail (a failover event). All load balance members have to fail before the standby member takes over. When one or more of the load balance members is restored (fallback), the restored team member(s) resumes the handling of the traffic. The LiveLink feature is supported only for this type of team.

What I'd like to do is create a port group consisting of 2 ports in Switch A. In doing this I believe that the combined throughput of both ports, 2Gbps, will be passed to the NIC team. This is an easy concept - it simply involves moving connecting NIC A and NIC B to the same switch, maintaining the existing team, and grouping the ports that each NIC is connected to in the switch.

The problem as I see it is that I lose redundancy. With NIC A and NIC B going to different switches it doesn't matter if one NIC or one switch go down, my server stays up (kinda stuck if both NICs or both switches go down but I don't really know how to account for that).

Anyway what I'd like to be able to do is keep redundancy at the NIC and switch levels AND boost the throughput from the switches to the server.

I think what I want can be accomplished by:
1. Adding 2 more NICs
2. Creating NIC TEAM A (comprised of 2 of the NICs) and connecting it to Switch A
3. Creating a group in Switch A to serve NIC TEAM A
4. Creating NIC TEAM B (comprised of the other 2 NICs) and connecting it to Switch B.
5. Creating a group in Switch B to serve NIC Team B
6. Creating NIC TEAM C which would be a failover-only team comprised of NIC TEAMS A & B.

What I believe this accomplishes is maintaining the safety net I put into place by providing failover across the switches (done with NIC TEAM C) while boosting throughput to the server by way of the grouping done in each switch.

Here's what I don't know:

Will this work as I think it will?

What is the benefit to grouping the ports in the switch, throughput?

If throughput is the benefit of grouping the switch ports how is it beneficial to provide the server with double or quadruple the throughput from the switch - we have a gigabit network so won't the boost in throughput also make more a substantial bottleneck once the data from the server passes through the switch on its way back out?

I've been told that I can't use two standalone switches as I want to because the switches may get confused when they each see the same MAC address and IP address coming from the server (a function of teaming). But SLB&F states specifically that each NIC in a team has its own MAC address. Does this help me in any way?

I am well aware at this point that if I had what 3Com calls stackable switches that this would all be very easy. I could then create a port group across Switch A and Switch B and preserve my current NIC team, achieving everything I want. Sadly, I went cheap with the switches because I had no intention of using any management features (we're a small company, I have no experience as a NetAdmin, and why spend the money?) until now. I'd like to make it work with what I've got.

On a related note, why would I use a VLan? I have a 50 node network and one or two tiny outer offices that connect to a terminal server. How could a VLAN benefit me?

Thanks for the help. Sorry this is such a long post.


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