Packets switched through Linux bridge have very high packet delay variation and latency?
I configured a very simple bridge under Debian Wheezy(kernel 3.2.0-4-686-pae). I simply created bridge interface with
brctl addbr br0 and added interfaces eth1 and eth2 into this bridge with
brctl addif br0 eth1 and brctl addif br0 eth2 commands. STP is disabled. However, the latency of frames switched is very high and fluctuating. For example RTT shown in
ping output fluctuates from 30 to 1100ms if I ping a router in the very same broadcast domain. Usually it is below 1ms. However, there seems to be no packet loss. CPU load on this Linux bridge is very low. According to
ip -s link show dev eth1 and ip -s link show dev eth2 there are no errors or drops. Both
eth0 and eth1 are Realtek PCI NIC's using the 8139too LKM. What might cause such behavior? Some sort of faulty queuing?
EDIT: one of the Realtek interfaces was problematic. I formed a bridge with new NIC.
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Does "one of the Realtek interfaces was problematic. I formed a bridge with new NIC" mean the problem is gone? – Hauke
Laging Dec 21 '14 at 15:38
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@HaukeLaging Yes. Later this NIC was not even detected by system, i.e. if I loaded the
8139too driver, then the 8139too 0000:00:0d.0: Chip not responding, ignoring board message was logged into kernel ring buffer. Finally I just replaced the NIC and now the bridge works as it should. – Martin
Dec 23 '14 at 11:23
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