What is Interface bonding
Bonding (or channel bonding) is a technology-enabled by the Linux kernel and Red Hat Enterprise Linux, that allows administrators to combine two or more network interfaces to form a single, logical “bonded” interface for redundancy or increased throughput. The behavior of the bonded interfaces depends upon the mode; generally speaking, modes provide either hot standby or load balancing services. Additionally, they may provide link-integrity monitoring.
Why use Interface bonding?
The two important reasons to create an interface bonding are :
1. To provide increased bandwidth
2. To provide redundancy in the face of hardware failure
One of the pre-requisites to configure a bonding is to have the network switch which supports EtherChannel (which is true in case of almost all switches).
Bonding modes
Depending on your requirement, you can set the bonding mode to any of the below 7 modes.
| Mode | Policy | How it works | Fault Tolerance | Load balancing |
|---|---|---|---|---|
| 0 | Round Robin | packets are sequentially transmitted/received through each interfaces one by one. | Yes | Yes |
| 1 | Active Backup | one NIC active while another NIC is asleep. If the active NIC goes down, another NIC becomes active. only supported in x86 environments. | Yes | No |
| 2 | XOR [exclusive OR] | In this mode the, the MAC address of the slave NIC is matched up against the incoming request’s MAC and once this connection is established same NIC is used to transmit/receive for the destination MAC. | Yes | Yes |
| 3 | Broadcast | All transmissions are sent on all slaves | Yes | No |
| 4 | Dynamic Link Aggregation | aggregated NICs act as one NIC which results in a higher throughput, but also provides failover in the case that a NIC fails. Dynamic Link Aggregation requires a switch that supports IEEE 802.3ad. | Yes | Yes |
| 5 | Transmit Load Balancing (TLB) | The outgoing traffic is distributed depending on the current load on each slave interface. Incoming traffic is received by the current slave. If the receiving slave fails, another slave takes over the MAC address of the failed slave. | Yes | Yes |
| 6 | Adaptive Load Balancing (ALB) | Unlike Dynamic Link Aggregation, Adaptive Load Balancing does not require any particular switch configuration. Adaptive Load Balancing is only supported in x86 environments. The receiving packets are load balanced through ARP negotiation. | Yes | Yes |
Creating the Network Bonding using nmcli
1. Creating the Bonding interface
1. Use the nmcli connection command without any arguments to view the existing network connections. You can shorten the “connection” argument to “con“. Example:
# nmcli connection NAME UUID TYPE DEVICE ens33 59b61d18-90ed-4c3c-97e0-6c9e0528f25f 802-3-ethernet ens33 ens37 c09f18e1-793b-4d60-9107-98762cf593a7 802-3-ethernet ens37
2. Include the “add type bond” arguments, and any additional information to create a network bond connection. The following example creates a bonded interface named bond0, defines the interface as bond0, sets the mode to “active-backup“, and assigns an IP address to the bonded interface.
# nmcli con add type bond con-name bond0 ifname bond0 mode active-backup ip4 192.168.219.150/24 Connection 'bond0' (1a75eef0-f2c9-417d-81a0-fabab4a1531c) successfully added.
The nmcli con command shows the new bond connection.
# nmcli connection NAME UUID TYPE DEVICE bond0 1a75eef0-f2c9-417d-81a0-fabab4a1531c bond bond0 ens33 59b61d18-90ed-4c3c-97e0-6c9e0528f25f 802-3-ethernet ens33 ens37 c09f18e1-793b-4d60-9107-98762cf593a7 802-3-ethernet ens37
3. The ‘nmcli con add type bond’ command creates an interface configuration file in the /etc/sysconfig/network-scripts directory. For example:
# cat /etc/sysconfig/network-scripts/ifcfg-bond0 DEVICE=bond0 BONDING_OPTS=mode=active-backup TYPE=Bond BONDING_MASTER=yes BOOTPROTO=none IPADDR=192.168.219.150 PREFIX=24 DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=yes IPV6_AUTOCONF=yes IPV6_DEFROUTE=yes IPV6_PEERDNS=yes IPV6_PEERROUTES=yes IPV6_FAILURE_FATAL=no IPV6_ADDR_GEN_MODE=stable-privacy NAME=bond0 UUID=1a75eef0-f2c9-417d-81a0-fabab4a1531c ONBOOT=yes
4. The ip addr command shows the new bond0 interface:
# ip addr show bond0
5: bond0: [BROADCAST,MULTICAST,MASTER,UP] mtu 1500 qdisc noqueue state DOWN qlen 1000
link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
inet 192.168.219.150/24 brd 192.168.219.255 scope global bond0
valid_lft forever preferred_lft forever
2. Creating the Slave Interfaces
1. For each interface that you want to bond, use the ‘nmcli con add type bond-slave‘ command. The following example adds the ens33 interface as a bond slave. The command does not include the con-name argument so a name is automatically generated. You can have the name set for the slave interfaces with the con-name argument.
# nmcli con add type bond-slave ifname ens33 master bond0 Connection 'bond-slave-ens33' (79c40960-6b2c-47ba-a417-988332affed1) successfully added.
2. The following example adds the ens37 interface as a “bond-slave“.
# nmcli con add type bond-slave ifname ens37 master bond0 Connection 'bond-slave-ens37' (46222a52-f2ae-4732-bf06-ef760aea0d7b) successfully added.
3. The nmcli con command shows the new connections.
# nmcli connection NAME UUID TYPE DEVICE bond0 1a75eef0-f2c9-417d-81a0-fabab4a1531c bond bond0 ens33 59b61d18-90ed-4c3c-97e0-6c9e0528f25f 802-3-ethernet ens33 ens37 c09f18e1-793b-4d60-9107-98762cf593a7 802-3-ethernet ens37 bond-slave-ens33 79c40960-6b2c-47ba-a417-988332affed1 802-3-ethernet -- bond-slave-ens37 46222a52-f2ae-4732-bf06-ef760aea0d7b 802-3-ethernet --
4. The nmcli con add type bond-slave commands create interface configuration files in the /etc/sysconfig/network-scripts directory. For example:
# cat /etc/sysconfig/network-scripts/ifcfg-bond-slave-ens33 TYPE=Ethernet NAME=bond-slave-ens33 UUID=79c40960-6b2c-47ba-a417-988332affed1 DEVICE=ens33 ONBOOT=yes MASTER=bond0 SLAVE=yes
# cat /etc/sysconfig/network-scripts/ifcfg-bond-slave-ens37 TYPE=Ethernet NAME=bond-slave-ens37 UUID=46222a52-f2ae-4732-bf06-ef760aea0d7b DEVICE=ens37 ONBOOT=yes MASTER=bond0 SLAVE=yes
5. The ip addr command includes “SLAVE” for the ens33 and ens37 interfaces and also includes “master bond0“.
3. Activating the Bond
1. You can use the nmcli command to bring up the connections. Bring up the slaves first, and then bring up the bond interface. The following commands bring up the slaves:
# nmcli connection up bond-slave-ens33 # nmcli connection up bond-slave-ens37
2. The following command brings up the bond0 interface:
# nmcli con up bond0
3. The ip addr command, or the ip link command, now shows the slave and the bond interfaces that are UP.
# ip link
2: ens33: [BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP] mtu 1500 qdisc pfifo_fast master bond0 state UP mode DEFAULT qlen 1000
link/ether 00:0c:29:54:f7:20 brd ff:ff:ff:ff:ff:ff
3: ens37: [BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP] mtu 1500 qdisc pfifo_fast master bond0 state UP mode DEFAULT qlen 1000
link/ether 00:0c:29:54:f7:20 brd ff:ff:ff:ff:ff:ff
4: bond0: [BROADCAST,MULTICAST,MASTER,UP,LOWER_UP] mtu 1500 qdisc noqueue state UP mode DEFAULT qlen 1000
link/ether 00:0c:29:54:f7:20 brd ff:ff:ff:ff:ff:ff
Viewing Network Bonding Information
1. Each network interface contains a directory in the /sys/class/net directory. For example:
# ls /sys/class/net bond0 bonding_masters ens33 ens36 ens37 lo
2. In this example, a network bond named ‘bond0’ exists. A directory of the same name exists that contains configuration information for that bond. For example:
# ls /sys/class/net/bond0 addr_assign_type bonding carrier_changes dormant gro_flush_timeout iflink lower_ens37 operstate queues subsystem uevent address broadcast dev_id duplex ifalias link_mode mtu phys_port_id speed tx_queue_len addr_len carrier dev_port flags ifindex lower_ens33 netdev_group power statistics type
3. Within this directory is a bonding directory that contains information for the bond0 interface. For example:
# ls /sys/class/net/bond0/bonding active_slave ad_aggregator ad_select arp_interval fail_over_mac mii_status num_unsol_na queue_id updelay ad_actor_key ad_num_ports ad_user_port_key arp_ip_target lacp_rate min_links packets_per_slave resend_igmp use_carrier ad_actor_sys_prio ad_partner_key all_slaves_active arp_validate lp_interval mode primary slaves xmit_hash_policy ad_actor_system ad_partner_mac arp_all_targets downdelay miimon num_grat_arp primary_reselect tlb_dynamic_lb
4. There are also directories that contain information for each of the slaves. For example:
# ls /sys/class/net/bond0/lower_ens33 addr_assign_type bonding_slave carrier_changes dev_port flags ifindex master operstate queues subsystem uevent address broadcast device dormant gro_flush_timeout iflink mtu phys_port_id speed tx_queue_len upper_bond0 addr_len carrier dev_id duplex ifalias link_mode netdev_group power statistics type
5. Following are some examples of viewing files in the /sys/class/net directory.
# cat /sys/class/net/bonding_masters bond0
# cat /sys/class/net/bond0/operstate up
# cat /sys/class/net/bond0/address 00:0c:29:54:f7:20
# cat /sys/class/net/bond0/bonding/active_slave ens33
# cat /sys/class/net/bond0/bonding/mode active-backup 1
# cat /sys/class/net/bond0/bonding/slaves ens33 ens37
6. Following is an example of viewing the /proc/net/bonding/bond0 file.
# cat /proc/net/bonding/bond0 Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011) Bonding Mode: fault-tolerance (active-backup) Primary Slave: None Currently Active Slave: ens33 MII Status: up MII Polling Interval (ms): 100 Up Delay (ms): 0 Down Delay (ms): 0 Slave Interface: ens33 MII Status: up Speed: 1000 Mbps Duplex: full Link Failure Count: 0 Permanent HW addr: 00:0c:29:54:f7:20 Slave queue ID: 0 Slave Interface: ens37 MII Status: up Speed: 1000 Mbps Duplex: full Link Failure Count: 0 Permanent HW addr: 00:0c:29:54:f7:34 Slave queue ID: 0
How to disable IPv4 or IPv6 on bonded interface
These steps are only needed if bond1 will not use an ipv4 or ipv6 address
# nmcli connection modify bond1 ipv4.method disabled
and/or
# nmcli connection modify bond1 ipv6.method ignore