Ping Replies

[thebdj]

I have seen this problem before and I remember that we resolved it but I was wondering if anyone had any ideas on what it may be.

When pinging across our network from our current location to various different locations using the -t switch there is an occasional reply saying 'Request timed out'. Now it's only about 1 in 20 to be honest but it does start to make us wonder as to certain things.

I wonder if there's too much cross-talk or noise somewhere along the circuit, maybe from where my machine is to the local switch/router.

If anyone has any bright ideas I would be most appreciative. I am not necessarily looking to sort this problem out as recognise exactly what is going on or could be going on.

Many Thanks
The BDJ

 

[Marcs41]

That is perfectly normal if you do that over thenet without a delay switch added.
Some destinations may disregard some pings because of a firewall (DoS attacks) or it is just to slow to respond in time and a ping gets lost.

Marc
[sub]If 'something' 'somewhere' gives 'some' error, expect random guesses or no replies at all. Please specify details.
Free Tip: The F1 Key does NOT destroy your PC![/sub]

 

[thebdj]

But is it perfectly normal inside your own network?

Cheers
The BDJ

 

[Marcs41]

Can be, slower hubs, traffic, a slow NIC somewhere ...
A -t option sends continu, so you should add the delay option too.

 

[thebdj]

Will give it a go, do you think this will allow for a more accurate result though. I was just thinking that with packets traversing the network every millisecond, surely this drop indicates that other non-ping packets will be dropping.

Cheers
The BDJ

 

[thebdj]

Sorry, remind me how I can add the delay in as well for the ping results.

Cheers

 

[Marcs41]

On a TCP/IP network, there will always be drops. If you use a sniffer, you would be surprised!


you have to add the -w xxx to allow more time before time-outs
ping /? will give you all options


Marc
[sub]If 'something' 'somewhere' gives 'some' error, expect random guesses or no replies at all. Please specify details.
Free Tip: The F1 Key does NOT destroy your PC![/sub]

 

[thebdj]

Sorry being blonde

I have used a sniffer and I am happy to accept that there are always dropped packets, I just thought that an average of 1 in 20 on a continuous ping seemed a little high.

Any Thoughts?

 

[Marcs41]

Like I said, it 'can' be. Traffic, hubs, switches, a bad or slow NIC, too long cable .. all things that may cause a loss.

 

[Marcs41]

Just tested it here with the -t, I get reply times of 1 ms, no drops.

You could also try ro increase the TTL

 

[thebdj]

Tried both of your ideas. It does seem that the frequency has become better for me as in 1 in 50 now with times of <10ms but there is still those drops. I was kinda hoping you said that in your network you had occasional ping drops as well

 

[Marcs41]

Hey .. I got the perfect network , haha.

No, where I am right now, there is no traffic and not many PC's or hubs, so I cannot compare it.
Maybe someone else here can try a test ping on the larger network?

But anyway, something on your LAN is slowing things down.
How many hubs and/or switches are there and how may Workstations (active) ?

 

[thebdj]

Well it's pretty large. 200-250 Workstations, 10+ switches and 5 routers spread over 4 sites.

Would be handy if someone in a larger network situation could help me out by doing the ping test that I am.

Cheers

 

[Marcs41]

Well, with that setup it does not surprise me.
And don't forget that a switch .. switches, they could be the reason.
Try in on a pure hub between 2 PC's on the same hub.
Oh, and of course mind your Default Gateway, if ot is on the far side of your LAN, your ping will traverse everything twice!

 

[sbutcher]

What type of connectivity do you have between your sites? If you ping between two of the other locations do you get the same results. In my experience a drop rate of 1 in 20 indicates a significant problem somewhere. Possibly a bad T-1 line, a congested Internet connection,a bad network card generating too much traffic or even a virus.

 

[thebdj]

I would put my neck on the line to say it is not a virus. Is there any easy of isolating a bad NIC and what would the symptoms be apart from maybe a shed-load of broadcasts? We have users connected on 100 Meg switches and the sites are connected via 2 meg fibre links routing through Cisco 2600 series routers.

Cheers

 

[Marcs41]

If you want to do that yourself, you will have to work by elimination.
Ping while disconnecting half the hubs or switches. Then the other half. Whichever gives the slower response, is to be narrowed down until you may finally find a PC, or even a hub or switch causing the delays.

Pings across the fibre should prove ok, but ping from a spot as close to the link itself to eliminate possible other glitches.

Have fun.