Appendix D. Bonding Options
You can bundle multiple physical NICs together to form a single logical channel known as a bond. Bonds can be configured to provide redundancy for high availability systems or increased throughput.
D.1. Network Interface Bonding and Link Aggregation Control Protocol (LACP)
Red Hat OpenStack Platform supports Linux bonds, Open vSwitch (OVS) kernel bonds, and OVS-DPDK bonds.
The bonds can be used with the optional Link Aggregation Control Protocol (LACP). LACP is a negotiation protocol that creates a dynamic bond for load balancing and fault tolerance.
On any network that interacts directly with virtual machine instances, Red Hat recommends the use of OVS kernel bonds (bond type ovs_bond) or OVS-DPDK bonds (bond type ovs_dpdk_bond) with LACP. However, do not combine OVS kernel bonds and OVS-DPDK bonds on the same node.
On control and storage networks, Red Hat recommends the use of Linux bonds with VLAN and LACP, because OVS bonds carry the potential for control plane disruption that can occur when OVS or the neutron agent is restarted for updates, hot fixes, and other events. The Linux bond/LACP/VLAN configuration provides NIC management without the OVS disruption potential. Here is an example configuration of a Linux bond with one VLAN.
params:
$network_config:
network_config:
- type: linux_bond
name: bond_api
bonding_options: "mode=active-backup"
use_dhcp: false
dns_servers:
` get_param: DnsServers
members:
- type: interface
name: nic3
primary: true
- type: interface
name: nic4
- type: vlan
vlan_id:
get_param: InternalApiNetworkVlanID
device: bond_api
addresses:
- ip_netmask:
get_param: InternalApiIpSubnetD.2. Open vSwitch Bonding Options
The Overcloud provides networking through Open vSwitch (OVS). The following table describes support for OVS kernel and OVS-DPDK for bonded interfaces. The OVS/OVS-DPDK balance-tcp mode is available as a technology preview only.
The bonding options described in the following table require OVS 2.9 or later.
| OVS Bond mode | Application | Notes | Compatible LACP options |
| active-backup | High availability (active-passive) | active, passive, or off | |
| balance-slb | Increased throughput (active-active) |
| active, passive, or off |
| balance-tcp (tech preview only ) | Not recommended (active-active) |
| active or passive |
You can configure a bonded interface in the network environment file using the BondInterfaceOvsOptions parameter as shown in this example:
parameter_defaults: BondInterfaceOvsOptions: "bond_mode=balance-slb"
D.3. Considerations for balance-tcp Mode
If you decide to use balance-tcp mode despite its tech preview status and the known performance issues, you must manually delete the following lines from each network interface configuration (NIC) file before deployment:
constraints:
- allowed_pattern: "^((?!balance.tcp).)*$"
description: |
The balance-tcp bond mode is known to cause packet loss and
should not be used in BondInterfaceOvsOptions.After you delete the constraint from each NIC file, you can set the bond mode option in the bond interface parameter:
BondInterfaceOvsOptions:
"bond_mode=balance-tcp"D.4. Linux Bonding Options
You can use LACP with Linux bonding in your network interface templates. For example:
- type: linux_bond
name: bond1
members:
- type: interface
name: nic2
- type: interface
name: nic3
bonding_options: "mode=802.3ad lacp_rate=[fast|slow] updelay=1000 miimon=100"-
mode- enables LACP. -
lacp_rate- defines whether LACP packets are sent every 1 second, or every 30 seconds. -
updelay- defines the minimum amount of time that an interface must be active before it is used for traffic (this helps mitigate port flapping outages). -
miimon- the interval in milliseconds that is used for monitoring the port state using the driver’s MIIMON functionality.
For more information on Linux bonding options, see 4.5.1. Bonding Module Directives in the Red Hat Enterprise Linux 7 Networking Guide.
D.5. Bonding Options
The following table provides some explanation of these options and some alternatives depending on your hardware.
|
|
Balances flows based on source MAC address and output VLAN, with periodic rebalancing as traffic patterns change. Bonding with |
|
| This mode offers active/standby failover where the standby NIC resumes network operations when the active connection fails. Only one MAC address is presented to the physical switch. This mode does not require any special switch support or configuration, and works when the links are connected to separate switches. This mode does not provide load balancing. |
|
|
Controls the Link Aggregation Control Protocol (LACP) behavior. Only certain switches support LACP. If your switch does not support LACP, use |
|
| Sets the LACP behavior to switch to bond_mode=active-backup as a fallback. |
|
| Set the LACP heartbeat to 1 second (fast) or 30 seconds (slow). The default is slow. |
|
| Set the link detection to use miimon heartbeats (miimon) or monitor carrier (carrier). The default is carrier. |
|
| If using miimon, set the heartbeat interval in milliseconds. |
|
| Number of milliseconds a link must be up to be activated to prevent flapping. |
|
| Milliseconds between rebalancing flows between bond members. Set to zero to disable. |
