12-08-2013 07:29 PM - edited 03-04-2019 09:48 PM
We have the following wan setup...
Site 1 - asr1006 with ds3 link to ISP
Layer 3 VPN from ISP
Site 2 - 3945 isr with ds3 link to isp
Users experience problems with streaming video between sites. For testing I connected a laptop directly to each site router and ran jperf between the two. In the jperf output I see lots of out of order packets. I think that must be causing the video problems. However, I can not recreate the out of order packets using IP SLA on the routers.
How might I test for out of order packets on the routers? Thank you.
12-09-2013 08:05 AM
You can configure Netflow and export the captured information into a collector.
Within the collector, you can verify the packet timestamp.
Regards,
Edison
12-09-2013 10:34 AM
I wasn't aware that netflow could monitor packet by packet statistics. Can you explain further?
Here are the configs I have now...
--- sla config
ip sla 200
udp-jitter 1.1.1.1 16384 num-packets 1000
frequency 30
ip sla schedule 200 life forever start-time now
-- netflow configuration
ip flow-cache timeout active 1
ip flow-export version 9
ip flow-export destination 2.2.2.2 9999
Thank you.
12-09-2013 11:12 AM
Sure,
NetFlow Analyzer accounts for the following details from the NetFlow Packets :
Source and destination IP address
Input and output interface number
Source and destination port number
Layer 4 Protocol
Number of packets in the flow
Total Bytes in the flow
Time stamp in the flow
Source and destination AS
TCP_Flag & TOS
Your global network configuration looks fine but also you need to enable netflow in the interface.
Regards,
12-09-2013 07:47 PM
I'm using what's up gold as my netflow collector. I see data rates by protocol but nothing that looks helpful to me.
I don't understand how netflow would help since it does not know transmittal time from the source. I feel like I'm missing something here.
12-10-2013 11:08 AM
I guess it depends on the collector but time stamp is definitely collected.
12-11-2013 11:36 AM
Hi Tod,
For out of order packets you'd need burst of traffic with very little spacing in between.
Something like ~10-20 ping echo requests with 0 timeout.
You won't see the reply in the CLI, because timeout is 0, but you could capture that with embedded packet capture.
That isn't really a good test though, because you've already seen that there is reordering with your test from the laptop. So the next step would be to go hop by hop and see where reordering is happening (i.e. per packet load sharing, combined with latency difference on two circuits). There is no per-packet load sharing, right?
Are you looking for a continuous test for the future, or are you looking to fix the problem?
12-11-2013 11:58 AM
There is no load per-packet load sharing. (unless the ISP is doing it)
I'm looking to fix the current problem.
I'm unable to see how netflow can help since it doesn't know the packet transmit time or what order to expect the packets in (as far as I can tell).
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