Configuring Network Bonding on RHEL 7,8
Configuring Network Bonding on RHEL 7,8
RHEL 7,8
Using NetworkManager
To create a bond connection:
nmcli con add type bond con-name bond0 ifname bond0 bond.options "mode=active-backup,miimon=1000" |
To add a port interface:
nmcli con add type ethernet slave-type bond con-name bond0-port1 ifname enp7s0 master bond0 |
Configure the IPv4 settings:
nmcli con modify bond0 ipv4.addresses '192.0.2.1/24' ipv4.gateway '192.0.2.254' ipv4.dns '192.0.2.253' \ |
Enables all ports automatically when the bond is enabled:
nmcli con modify bond0 connection.autoconnect-slaves 1 |
Activate the connection:
nmcli con up bond0 |
Display the status of the bond:
cat /proc/net/bonding/bond0 |
Upstream Switch Configuration Depending on the Bonding Modes
Apply the following settings to the upstream switch depending on the bonding mode:
| Bonding mode | Configuration on the switch |
|---|---|
| 0 - balance-rr | Requires static Etherchannel enabled (not LACP-negotiated) |
| 1 - active-backup | Requires autonomous ports |
| 2 - balance-xor | Requires static Etherchannel enabled (not LACP-negotiated) |
| 3 - broadcast | Requires static Etherchannel enabled (not LACP-negotiated) |
| 4 - 802.3ad | Requires LACP-negotiated Etherchannel enabled |
| 5 - balance-tlb | Requires autonomous ports |
| 6 - balance-alb | Requires autonomous ports |
The different network bonding modes
The Linux bonding driver provides link aggregation. Bonding is the process of aggregating multiple network interfaces in parallel to provide a single logical bonded interface. The actions of a bonded interface depend on the bonding policy that is also known as mode. The different modes provide either load-balancing or hot standby services.
The following modes exist:
Balance-rr (Mode 0)
Balance-rr uses the round-robin algorithm that sequentially transmits packets from the first available port to the last one. This mode provides load balancing and fault tolerance.
This mode requires switch configuration of a port aggregation group, also called EtherChannel or similar port grouping. An EtherChannel is a port link aggregation technology to group multiple physical Ethernet links to one logical Ethernet link.
The drawback of this mode is that it is not suitable for heavy workloads and if TCP throughput or ordered packet delivery is essential.
Active-backup (Mode 1)
Active-backup uses the policy that determines that only one port is active in the bond. This mode provides fault tolerance and does not require any switch configuration.
If the active port fails, an alternate port becomes active. The bond sends a gratuitous address resolution protocol (ARP) response to the network. The gratuitous ARP forces the receiver of the ARP frame to update their forwarding table. The Active-backup mode transmits a gratuitous ARP to announce the new path to maintain connectivity for the host.
The primary option defines the preferred port of the bonding interface.
Balance-xor (Mode 2)
Balance-xor uses the selected transmit hash policy to send the packets. This mode provides load balancing, fault tolerance, and requires switch configuration to set up an Etherchannel or similar port grouping.
To alter packet transmission and balance transmit, this mode uses the xmit_hash_policy option. Depending on the source or destination of traffic on the interface, the interface requires an additional load-balancing configuration. See description xmit_hash_policy bonding parameter.
Broadcast (Mode 3)
Broadcast uses a policy that transmits every packet on all interfaces. This mode provides fault tolerance and requires a switch configuration to set up an EtherChannel or similar port grouping.
The drawback of this mode is that it is not suitable for heavy workloads and if TCP throughput or ordered packet delivery is essential.
802.3ad (Mode 4)
802.3ad uses the same-named IEEE standard dynamic link aggregation policy. This mode provides fault tolerance. This mode requires switch configuration to set up a Link Aggregation Control Protocol (LACP) port grouping.
This mode creates aggregation groups that share the same speed and duplex settings and utilizes all ports in the active aggregator. Depending on the source or destination of traffic on the interface, this mode requires an additional load-balancing configuration.
By default, the port selection for outgoing traffic depends on the transmit hash policy. Use the xmit_hash_policy option of the transmit hash policy to change the port selection and balance transmit.
The difference between the 802.3ad and the Balance-xor is compliance. The 802.3ad policy negotiates LACP between the port aggregation groups. See description xmit_hash_policy bonding parameter.
Balance-tlb (Mode 5)
Balance-tlb uses the transmit load balancing policy. This mode provides fault tolerance, load balancing, and establishes channel bonding that does not require any switch support.
The active port receives the incoming traffic. In case of failure of the active port, another one takes over the MAC address of the failed port. To decide which interface processes the outgoing traffic, use one of the following modes:
- Value 0: Uses the hash distribution policy to distribute traffic without load balancing
- Value 1: Distributes traffic to each port by using load balancing
With the bonding option tlb_dynamic_lb=0, this bonding mode uses the xmit_hash_policy bonding option to balance transmit. The primary option defines the preferred port of the bonding interface.
See description xmit_hash_policy bonding parameter.
Balance-alb (Mode 6)
Balance-alb uses an adaptive load balancing policy. This mode provides fault tolerance, load balancing, and does not require any special switch support.
This mode Includes balance-transmit load balancing (balance-tlb) and receive-load balancing for IPv4 and IPv6 traffic. The bonding intercepts ARP replies sent by the local system and overwrites the source hardware address of one of the ports in the bond. ARP negotiation manages the receive-load balancing. Therefore, different ports use different hardware addresses for the server.
The primary option defines the preferred port of the bonding interface. With the bonding option tlb_dynamic_lb=0, this bonding mode uses the xmit_hash_policy bonding option to balance transmit. See description xmit_hash_policy bonding parameter.
