Comments on: Active / Standby etherchannels?

By: Duncan Epping

Duncan Epping — Tue, 03 Nov 2009 16:20:05 +0000

What you want to achieve is not possible. You need to either have a 4 nic etherchannel to a single switch or create two seperate vswitches with each two nics bonded as an etherchannel. Another option would be, and this is the most redundant, flexible and simple solution: 4 nics, two attached to each 3750, NO etherchannels, Virtual PortID load balancing!

By: LM

LM — Tue, 03 Nov 2009 09:02:37 +0000

We have two Cisco 3750’s (not stacked). We configured this just the same way you explained in this article. I want to get rid of mac flapping, so what is the best way? Is there a way to keep the performance of the etherchannel and to use the 4 nics? It’s very easy when you’re using stackable switches, just add the 4 nics as active. But what do you need to do when you have two seperate switches, connected with an etherchannel? If I’m using an other teaming method, can I use two active (to switch1)/two passive nic (to switch2) config? Can I use the 4 NIC “Virtual Port ID” based load balancing method (two active (to switch1)/two passive nic (to switch2)) in this case and if I’m using this will it perform the same way?

By: JGrote

JGrote — Fri, 16 Oct 2009 14:57:45 +0000

For those wondering why you would etherchannel instead of load balance based on port ID, the reason is because when you do that, you get more effective load balancing, because it is balanced on source/dest IP address at the ESX host and can be balanced at the TCP conversation level at the switch.

In the example of a file server, a single file transfer from the server to the client can only go a maximum of 1Gbps (1 conversation) using both methods, but two transfers from two different clients to the file server will go at 1Gbps each, wheras it would still be 1Gbps shared with the virtual port ID method. This all assumes your disk storage can go that fast .

Again, most workloads won’t utilize it, but shared SQL servers, File Servers, and Backup servers are the most common reasons to get improved performance using etherchannel over the standard virtual port ID, but virtual port ID is way simpler and doesn’t require expensive switches for proper redundancy, and what I generally recommend unless they either (a) already have something like 3750’s or (b) have a need to meet the requirement stated above but aren’t willing to go to 10Gb.

By: Cliff Jeffcoat

Cliff Jeffcoat — Wed, 14 Oct 2009 16:14:08 +0000

That is a good reason for MEC with stacked 3750’s and use three 1 Gb connections. More than likely only one port will fail and you can maintain your 2 Gb link requirement and save the 4th port all together.

By: Nevynxxxx

Nevynxxxx — Tue, 13 Oct 2009 14:07:42 +0000

True, from a networking side, it’s nice to treat ESX as “just another switch” and cross switch Etherchannel it off in the same way you do any other switch…

I think we are agreed that having half your NICs sitting doing nothing isn’t too useful!

By: Duncan Epping

Duncan Epping — Tue, 13 Oct 2009 10:27:40 +0000

Yes but a 4 NIC “Virtual Port ID” based load balancing “link” to the switches would also work fine. So why make it more complex than needed?

By: Nevynxxxx

Nevynxxxx — Tue, 13 Oct 2009 09:34:32 +0000

@ Gabrie – Why have a single active connection, when you you can have two active connections that keep working even if one connection fails? That’s why people use etherchannels.
If you are dedicating two ports to each vNIC for failover, you may as well use them.

By: Duncan

Duncan — Tue, 13 Oct 2009 08:21:15 +0000

Good question Jonb157, no clue why they wanted to have it like this. They couldn’t give me a justification for it. I received the phone call because the local partner did not have a clue what was happening and happen to know me… and I knew the customer.

By: Malaysia VMware

Malaysia VMware — Tue, 13 Oct 2009 02:58:20 +0000

I would said only use > 1GB nic for enhanced storage networking but not really for service console and vmkernel.

By: jonb157

jonb157 — Mon, 12 Oct 2009 16:56:31 +0000

Duncan, we use this setup but with 4 active nics all in a team using IP Hash. Why wouldn’t this particular customer “use” the two nics instead of keeping them in standby?