RHEV: How to Configure LACP Ports on a Cisco Catalyst Switch

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Here is how to configure ports on a Cisco Switch for use as LACP (mode 4) uplinks for RHEV (Red Hat Enterprise Virtualization). Note that the configuration that I have defined below may need to be tweaked a bit depending on your configuration. I am not exactly using the most recent equipment in my lab at home.

Note that all configurations are on a Cisco 3560G unless otherwise noted.

RHEV Uplink Ports – Trunk Mode

Configure your port channel similar to what is shown below. This configuration allows you to trunk multiple vlans. VLAN tagging will be required on the RHEV side.

interface Port-channel1
description trunk to RHEV Host1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 101,192
switchport mode trunk
spanning-tree portfast disable
spanning-tree bpduguard disable
spanning-tree guard root

Below is the configuration for the first physical port in the port channel.

interface GigabitEthernet0/9
description uplink to ETH0, RHEV Host1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 101-104,192
switchport mode trunk
channel-protocol lacp
channel-group 1 mode active

Below is the configuration for the second physical port in the port channel.

interface GigabitEthernet0/10
description uplink to ETH1, RHEV Host1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 101-104,192
switchport mode trunk
channel-protocol lacp
channel-group 1 mode active

RHEV Uplink Ports – Access Mode

Configure your port channel similar to what is shown below. In this configuration you are configuring an access port. No VLAN tagging required on the RHEV Side

interface Port-channel2
description Uplink to RHEV02
switchport access vlan 101
switchport mode access
spanning-tree portfast disable
spanning-tree bpduguard disable
spanning-tree guard root

Below is the configuration for the first physical port in the port channel.

interface GigabitEthernet0/5
description Uplink to RHEV02 – ETH0
switchport access vlan 101
switchport mode access
channel-protocol lacp
channel-group 2 mode active

Below is the configuration for the first physical port in the port channel.

interface GigabitEthernet0/6
description Uplink to RHEV02 – ETH1
switchport access vlan 101
switchport mode access
channel-protocol lacp
channel-group 2 mode active

Additional Information

The port configuration that you need to use for RHEV (or KVM, or XEN) is going to be a bit different than what your network administrator may be used to configuring for ESX.  There are actually three settings which might give your network admin might be initially opposed to.  A bit about those below.

> spanning-tree portfast disable

Portfast is enabled when connecting to an end device such as a server, and is disabled when connecting to another layer 2 device such as a switch. With RHEV you are creating a software switch internal to the server, so portfast needs to be disabled.

> spanning-tree bpduguard disable

A Bridge Protocol Data Unit, is a data message sent between switches. Since we are creating software switches in RHEV, we need to allow BPDU. So we need to disable BPDU guard which will down a port if a BPDU data message is received.

> spanning-tree guard root

Root Guard allows the port to participate in STP. However, unlike BPDU Guard which will disable a port upon receipt of a BPDU data unit, the Spanning Tree Root Guard feature will allow BPDU’s through a port to maintain the spanning tree topology, however if it receives a superior BPDU, which indicates that another switch is trying to become the root bridge it will err-disable the port.

Addendum

Below is the configuration that I have in place on a Cisco 2950.

Below is the configuration on the Port-Channel itself.

interface Port-channel2
description LACP to RHEV
switchport trunk allowed vlan 101-104,192
switchport mode trunk
flowcontrol send off
spanning-tree portfast disable
spanning-tree bpduguard disable
spanning-tree guard root

Below is the configuration on the first physical port in the bond

interface FastEthernet0/20
description port-chan 2 interface
switchport trunk allowed vlan 101-104,192
switchport mode trunk
channel-group 2 mode active
channel-protocol lacp

Below is the configuration on the second physical port in the bond

interface FastEthernet0/21
description lacp port channel 2
switchport trunk allowed vlan 101-104,192
switchport mode trunk
channel-group 2 mode active
channel-protocol lacp

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