Ping with Packet Size 1500 Costing Bandwidth 2 Mbps

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Sep 20th, 2007
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Dear All,

I'm doing ping test PTP connection with datagram size 1500 with Cisco Router 2600 at both side. This ping test costing almost 2.5 Mbps bandwidth. Could someone explain about this ? Thanks a lot.

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paul.matthews Thu, 09/20/2007 - 23:54
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How exactly are you doing the ping? If from a Cisco router, then the "next" echo request will be sent as soon as we get a reply to the "last" one, or it times out, so it can easily eat quite a bit of bandwidth if you start a large ping with a high count.

This is one of my fave tests though for simply throwing a load of traffic at a link - high count, large size, zero timeout means the router will send either a full link or as many as it can generate!


jakskal07 Fri, 09/21/2007 - 00:45
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Hi Paul,

Thank you very much for your reply. I'm pinging from Cisco Router. Can you give me the link regarding this topics.



jakskal07 Fri, 09/21/2007 - 04:11
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Thanks Paul,

Is there any ping or interface parameter that need to change, so if we do ping with datagram size 1500, didn't cost much bandwidth resource. I have problem with ping test in 1 Mbps ethernet link, because it's produce some RTO.

paul.matthews Fri, 09/21/2007 - 04:58
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If you are doing this on a live link, keep the count down - even on a smallish link, a count of five with 1500 will not be a big deal.

You could use QoS on the link to constrain the amount of bandwidth pings can use, but the effect of that may well be to cause more timeouts.

What are you trying to do with the large pings? That is probably key.

You send a lot of big packets quickly, you will use bandwidth. Either send them smaller or slower if you don't want the bandwidth used up.

Slower is awkward on Cisco routers, as there does not appear to be an interval parameter, all you can do is reduce the count and issue the command less frequently. Windows again does not have a parameter, but behaviour is different - IIRC it is every 2 secs. I also have a linux system and that has an interval parameter.

As for timeouts - remeber what I said earlier - the "next" request only gets sent on timeout or receipt. Unless timeout is very short, ping should not use so much bandwidth that pings start to fail.


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