Are there any concerns of trouble for bonding mode 3 (broadcast mode)?
Environment
- Red Hat Enterprise Linux
- bonding, mode 3
- broadcast
Issue
- Are there any concerns of trouble for bonding mode 3 (broadcast mode)?
Resolution
In bonding mode 3, packets are transmitted on all slave interfaces. Thus the traffic grows to double. If you use the mode 3, you need to design the system for double traffic. Since also other modes provide fault tolerance, there is usually no strong reason to use the bonding mode 3. Review your system design.
From Documentation/networking/bonding.txt:
The balance-rr, balance-xor and broadcast modes generally require that the switch have the appropriate ports grouped together. The nomenclature for such a group differs between switches, it may be called an "etherchannel" (as in the Cisco example, above), a "trunk group" or some other similar variation.
For these modes, each switch will also have its own configuration options for the switch's transmit policy to the bond. Typical choices include XOR of either the MAC or
IP addresses. The transmit policy of the two peers does not need to match. For these three modes, the bonding mode really selects a transmit policy for an EtherChannel group; all three will interoperate with another EtherChannel group.
Comments
- See the bonding.txt that is provided by a kernel-doc package. You can know other modes and examples.
- We have reports of higher network latency and higher CPU consumption for bonding mode 3, compared to other bonding modes
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