How to test Ring such as EAPS or RSTP recovery time?

Does anyone know how to test Ring or RSTP recovery time? Any tools I can use? Extreme networks declare the EAPS recovery time is 50ms.

Thanks alot, st

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without more information on exactly what you want to test and the resources avaiable to you it is difficult to give precise recommendations however I would want:-

Some way of verifying the actual path in use network equipment commands Some way of interrupting the path shutdown interfaces disconnect wires Some way of verifying he failover time Ssay use iperf to send stream of udp traffic of some known rate and on the receiver use wireshark to capture the packets. Then look at the timestamps and the iperf interface to look at the numeber of "lost" packets.

There are commercial test tools available Spirent smartbits - maybe There is a Japanese company that does high end test tools I forget the name sorry.

netperf or tcpdump may be more to your liking than iperf.

One thing that you need to consider is that a real in-service failure may not be as tidy as the "failure" you get when pulling a wire. STP for example (posssibly not RSTP - I am not really that familiar with it) was and is susceptible to unidirectional link failures where STP does not correctly detect a link failure when one of the directions of an ethernet link becomes disconnected but the other direction does not.

Cisco has a fix - UDLD. UniDirectional Link Detection. This uses multicast frames so the transport needs to accomodate them.

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Thanks, What i am using some tools are SMB and IXIA either check Rx/Tx or use wireshark to see timestamps. Since the results are not consistent, so I am looking for a dedicate tool or equivalent for Ring/STP/RSTP,then I can repeat test it very quick. Does any tools has Ring/STP/RSTP recovery time measurement feature. just like a running watch. Any suggestions? st

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at work we have used Smartbits and Agilent testers of various flavours.

however - what may help more is to describe how we do it.

you want a tester that generates a packets stream at "reasonable" load

- at least 1000 pps if you want 1mSec resolution, and you want the recieve section to show a graph of no of packets/ unit time making it thru the link.

then you break the working link and look at the graph during the recovery time.

if you want some more paranoia, repeat at various load levels, from very low load to more than 100% applied, since the stuff may react differently under different traffic conditions.

make sure you simulate various faults - physical fibre disconnect gets signalled very quickly.

however - i dont like the idea of relying on spanning tree of any flavour to handle network repair.

spanning tree doesnt react well to some error types, since the "suppress loop" packets go in the opposite way across links to potential looping packets, some types of 1 way link fault can convert a working "resilient" ring into a broadcast packet generator.

something like OSPF and routing copes much better with the hassles real life throws at networks.

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Thanks, Which tool can show graphic recovey time? st

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we used the graphing stuff that comes with the agilent console - but all you need is something that shows traffic load as a graph and the timescales you want.

if your traffic generator doesnt come with a stats display. then wireshark may be able to do it.

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note - this is just looking at arrival stats - ideally you want to tag every frame you send and make sure how many you lose during the topology change, and that the ones that survive, stay in order etc.

but - just seeing how big a gap between cut link and recovery gets you most of the way there....

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This is a fine plan from Stephen.

Send with say iperf (UDP) and run Wireshark on the iperf receiver (or otherwise) and use the ioGraph as described. (filter on the iperf traffic).

If iperf does not sequence number the packets in the data portion then you could use the IP Identification field

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verify how many packets had been lost and if any had been re-ordered, if that was required.

Wireshark will display these graphs in real time as the packets are captured.

I get the idea that you are looking for some sort of automated tester that just magically displays the failover time. I doubt that such a thing will be available.

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