- Blue, 1500 points or more
I am running a number of sites with 4 circuits between them using load balance by packet.
They work well as far as balance goes but I have had issue with file transfer throughput being very low. During testing I can actually get better throughput by shutting down 2 of the circuits.
There are no errors anyplace and all circuits are exactly the same as far as speed and latency.
After getting a packet capture from both client machines there are a huge number of packet retransmissions. There is no actual loss of any packet in the capture so these are not really valid retransmissions.
From what I can tell it is due to the packets arriving out of order. This causes many acks to be sent for the same seq number which the far end decides is loss and retransmits. From reading the RFC it appears that 3 is the magic number to cause a retransmission.
I know I can use multilink ppp to solve the out of order issue but it increases the knowledge level to support. I have a few NOC guys that will not understand that circuits can be down but still appear to ping.
Anyone suggestions. I have been looking to see if there is any parm in the tcp stack that would affect this but this appears to be very fundamental to tcp.