Home > 10GbE, Hardware, Home Lab, IBM, RackSwitch > HOWTO: IBM RackSwitch G8124 – Stacking and Port Channels

HOWTO: IBM RackSwitch G8124 – Stacking and Port Channels

Welcome to a work in progress J I fully suspect I’ll end up having to circle around and update some of this as I actually get more opportunity to test. I’m still working on some infrastructure in the lab to let me test these switches to their fullest, but in the meantime I’m looking to try to figure out how to get them setup the way I would if I had them at a client site. In general, this means supporting stacking or vPC LACP Port Channels, and connectivity to Cisco Nexus 5548’s.

I managed to find a PDF that shows just such a configuration: http://www.fox-online.cz/ibm/systemxtraining/soubory/czech-2013-bp-final_slawomir-slowinski.pdf

The first figure covers a scenario with teamed NIC’s, with either a Windows host or vSphere ESXi with vDS and LACP:


The second option shows how one might do it with individual non-teamed NIC’s:


The importance of these slides is that the confirm:

  • Cisco Nexus vPC connectivity if certainly a valid use case.
  • The IBM/BNT/Blade terminology for vPC is vLAG – I can live with that

What isn’t shown on THESE slides is some model information:

  • IBM G8000 48x 1GbE switches DO support stacking
  • IBM G8052 52x 1GbE switches do NOT support stacking, but support vLAG
  • IBM G8124 24x 10GbE switches do NOT support stacking, but support vLAG
  • IBM Virtual Fabric 10GbE BladeChassis switches DO support stacking

So there goes my hope for stacking. Not really the end of the world, if it supports vPC(vLAG). So with that in mind, we’ll move on.

I did manage to find a fellow who’s documented the VLAG and VRRP configuration on similar switches: http://pureflexbr.blogspot.ca/2013/10/switch-en4093-vlag-and-vrrp-config.html

So with some piecing together, I get, for Switch 2 (Switch 1 was already configured):

# Configure the LACP Trunk/Port-Channel to be used for the ISL, using ports 23 and 24

interface port 23-24


lacp mode active

# Set the LACP key to 200

lacp key 200

pvid 4094



# Configure VLAN 4094 for the ISL VLAN and move the ports into it.

vlan 4094


name "VLAN 4094"

member 23-24


# Set a new STPG of 20 with STP disabled

no spanning-tree stp 20 enable

# Add ports 23 and 24 to said STPG

interface port 23-24

no spanning-tree stp 20 enable


# Create the VLAN and IP Interface

interface ip 100

# Remember that this is on Switch2, so it is using IP2

# Change this when configuring Switch1

ip address

# configure this subnet configuraiton for VLAN4094

vlan 4094




# Configure the vLAG

vlag tier-id 10

# Indicate that the ISL VLAN is 4094

vlag isl vlan 4094

# As we’re on Switch2, this IP will be for Switch1 as the Peer

vlag hlthchk peer-ip

# Specify that same LACP ISL key of 200

vlag isl adminkey 200

# Enable the VLAG

vlag enable


If all goes well, you’ll see:


Sep 25 22:58:02 NW-IBMG8124B ALERT vlag: vLAG Health check is Up

Sep 25 22:58:11 NW-IBMG8124B ALERT vlag: vLAG ISL is up

Now, the questions I have for this:

· How do I create an actual vLAG – say using Ports 20 on both switches?

· What traffic is passing on this vLAG ISL? Is this just a peer-configuration check, or is it actually passing data? I’m going to assume it’s functioning as a TRUNK ALL port, but I should probably sift through the docs

· When will I have something configured that can use this J

Expect me to figure out how to configure the first in the next few days. It can’t be that much harder. In the meantime, I’m also building up a HDD+SSD StarWind SAN in a host with 2x 10GbE SFP+ that should let me configure port channels all day long. For now, I don’t really need them, so it might be a bit before I come back to this. Realistically, for now, I just need ISCSI, which doesn’t really want any LACP, just each switch/path to be in its own subnet/VLAN/fabric, with individual target/initiator NIC’s, unteamed. So as soon as I get a device up that can handle 10GbE traffic, I’ll be testing that!

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