环境
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 5
- Red Hat Enterprise Linux 4
- Mode 0 (round-robin) bonding device
问题
- Using a mode 0 bond, when using a tool such as
tcpdump or ping, half of all traffic appears to be lost inexplicably.
决议
- From the bonding.txt file:
Raw
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.
- Ensure that the switch has an appropriate Etherchannel configured to support a mode 0 bond - if it does not, this must be configured for the bond to work properly, otherwise there is likely no return path to the server resulting in up to half of all traffic lost.
根源
- If a switch is unaware of a mode 0 bond on a system, it will likely see a flapping MAC address as each of the interfaces on the server repeatedly ARP out their respective addresses with varying IP's. This can cause traffic to be lost on the return-trip, as traffic is incorrectly routed or dropped by the switch as it is not configured to accommodate the behavior of the bond, necessitating the need for an etherchannel on the switch which will allow this behavior.
诊断步骤
- Symptoms associated with this occurring have been application slowness, lost
ping replies when contacting the server, and loss of traffic seen in tcpdump from the target server to a foreign host.
