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Have a VPLS network connecting 6 different sites back to our data center. Each site has a dedicated 50 MB connection with bursting up to 100 MB. Trying to do a file migration from one site to the data center and I'm only getting .5-.7 MBytes the other sites are fine. Tried doing some captures on the VPLS interface while testing with iperf and I'm seeing retransmissions and unseen segment packets. Not sure if this could be causing the slowness or not.

Here is a snippet of the capture

asked 13 Apr '16, 21:32

wargresh's gravatar image

accept rate: 0%

edited 14 Apr '16, 05:47

you have not taken capture from beginning but it looks that RTT is around 2 ms,regarding your IPERF Testing on port 5001,i could see your iperf client only sending 17032 bytes/rtt so 17032*8 = 136256 bits and RTT is approx 2 ms = 136256/.002 = 68 mbits/sec.In your capture there are retransmission as well with RTO of 300 ms,no delayed the slowness could be due to stop acking packets that caused RTO to kick in.if you can take a capture on you could find out the reason.

(14 Apr '16, 23:30) kishan pandey

or i feel didn't received the packets,could be packet dropped.

(14 Apr '16, 23:40) kishan pandey


Thanks for the information. I have performed a capture on specifying the iperf traffic. Here is the link:

(15 Apr '16, 07:26) wargresh

yes,there is packet drop, didnt received packets and because iperf is only sending 16k bytes/rtt and waits for ack before sending any data,due to this behaviour fast retransmit is not triggered and sender is waiting for rto

(15 Apr '16, 10:14) kishan pandey
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question asked: 13 Apr '16, 21:32

question was seen: 937 times

last updated: 15 Apr '16, 10:14

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