Comments on: Server NIC Aggregation to a Cisco Switch

By: Aaron Conaway

Aaron Conaway — Fri, 17 Jul 2009 22:44:14 +0000

The bonded interfaces on the server shouldn’t switch traffic, so there’s no danger of creating a switching loop. I wouldn’t expect any problems having multiple bonded pairs from the server to two different switches that are EtherChannelled together.

I hope that works for you. Let me know the result.

By: Kolars

Kolars — Fri, 17 Jul 2009 20:11:55 +0000

Good, I’m glad you suggested the 2nd option. My thought was to attempt the “2 pairs – one to each switch” solution but since the switches have an etherchannel between them I was curious how that would work since that would basically create a loop. My instinct would tell me that spanning tree would block one logical pair to break the loop but I’m not entirely sure if it works the same with all the bonding and channeling that would be happening. Any further thoughts?

By: Aaron Conaway

Aaron Conaway — Fri, 17 Jul 2009 16:58:58 +0000

Thanks for the question, Kolars.

I’m not sure what the best practice for 4 NICs in an ESX server is, so let’s simplify it for me. Let’s say you have 2 NICs in the ESX server doing VLAN tagging. You would cable these to two different modules of the 4500 (or the same if you’re adventurous) and configure those ports as an EtherChannel like in the example above. The difference is that you would configure the Port-Channel as a trunk the same way you do between your 4500s.

int Port-channel 1
 speed 100
 duplex full
 switchport
 switchport trunk encapsulation dot1q
 switchport mode trunk

Since the 4500s don’t support StackWise, you can’t put all the NICs across both switches and have them in the same channel-group. Can you bond two pairs of NICs into two separate logical interfaces to use? If so, you could have a pair into one 4500 on a channel-group and the other pair on the other 4500 in another channel-group.

By: Kolars

Kolars — Fri, 17 Jul 2009 16:29:32 +0000

What if you have a need to trunk multiple VLANs to an ESX server in the following environment? We recently had a supervisor die in one switch and didn’t have NIC’s connected to the other switch.

- Have 2 4500′s etherchanneled together.
- Have 3 line cards in each switch
- Switches are running GLBP
- 4 NIC’s in each ESX servers.

How do I use multiple NICs to truck multiple VLAN to servers from each switch? Will spanning tree play a role in this?

By: DoDzMaNo

DoDzMaNo — Mon, 11 May 2009 06:58:18 +0000

thanks, Aaron..

By: Aaron Conaway

Aaron Conaway — Wed, 15 Apr 2009 13:44:18 +0000

Good question. Mode 1, which is active-backup, has a primary NIC running as normal, and, in case of link failure, the backup NIC takes over. From the switch’s perspective, it just looks like the server was recabled to another port. No additional switch configuration is required; just make sure both ports are in the same VLAN.

By: welbow

welbow — Wed, 15 Apr 2009 01:41:24 +0000

So is this required if the server’s NICs are in active-passive mode where only one NIC is active at a time?