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How many ms should it take to cross the United States?

Posted on 2011-10-13
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For privately owned connections across the US how many ms should it take?

We are taking 60ms and I don't know wether that is fast or slow.

Most of our local equipment and links in the city take 0ms RTT.

Should we focus on a 3ms RTT to our local switch or the 60ms RTT from the coast to coast connection?

We are troubleshooting VOIP packet loss but do not have any packet loss indicated on our interfaces or pings.
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Question by:Dragon0x40
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RPPreacher earned 1000 total points
ID: 36968851
Speed of light is ~186 miles per ms.

At its widest, distance across U.S. is 3400 miles or 18 ms.  36 ms RTT.

Add 1-2 ms per hop (router).

60 ms is not bad.
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by:ddiazp
ddiazp earned 1000 total points
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60ms is decent for across the US connections, the 3ms to the local switch though -- where exactly is this switch? same city? same building same office?

Have you measured performance through each one of the devices the VOIP packets go through? (bandwidth, packets/second, etc). Are you working with Cisco gear? what types of phones do you use?

Is CoS configured where needed?
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by:Dragon0x40
ID: 36970592
Is 3ms really that much?

The 3ms delay is to a local firewall about 5 miles away over a Cisco Optical Network System.

It probably should be <1 ms so we need to find out if it is the link, the intermediate switch or the firewall.

Avaya phones.

Tracing route to 1.2.3.4 over a maximum of 30 hops (Public IP Address)

  1     1 ms    <1 ms    <1 ms  local 6500 on local lan (Private IP Address)
optical transport network
3750 layer 2 switch with 1gb fiber port (5 miles away)
  2     2 ms     3 ms     4 ms  Firewall 2.3.4.5 (Public IP Address)
  3     3 ms     2 ms     2 ms  Connection to ISP (Public IP Address) 3.4.5.6
  4    60 ms    60 ms    60 ms  ISP router 6.7.8.9 (Private IP Address)
  5    60 ms    61 ms    60 ms  Remote site external screening router 7.8.9.10 (Public IP Address)
  6    60 ms    60 ms    60 ms  1.2.3.4 (Public IP Address)
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Author Comment

by:Dragon0x40
ID: 36970607
I forgot to add that all are switches that have qos enabled have "mls qos trust dscp" on the interfaces
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by:Darr247
ID: 36970656
5 miles geographically doesn't mean 5 miles of wire.

According to my telco there is almost 24,000 feet of wire between my house and the nearest switching office, which is only 2 miles away as the crow flies.
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by:ddiazp
ID: 36970683
Looks fine, though delay looks a bit high it shouldn't account for noticeable VOIP issues.

Have you tried looking at interface counters/statistics for main links to see how saturated they are (not just pakcet drop), maybe to see if there are errors on any interfaces instead?
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by:rochey2009
ID: 36970735
What is the bandwidth of the WAN link?
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by:inbox788
ID: 36971319
What kind of firewall are you dealing with? What features are turned on? If it's a stateful firewall, 3ms isn't anything to sweat at. Although stateless firewalls are generally less than that, it's still not very significant, unless you've got other issues.

You said, "We are troubleshooting VOIP packet loss but do not have any packet loss indicated on our interfaces or pings." I don't see that you're having any problems. Are you? Seems like you're just trying to gauge your network  performance, and it's quite good. What kind of bandwidth and load do you have planned? How are you stress testing?

http://www.voip-info.org/wiki/view/How+To+Debug+and+Troubleshoot+VOIP
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by:RPPreacher
ID: 36971353
IPSla might help you identify VoIP issues.  SolarWinds.com has a good tool with a 30 day trial.
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by:Dragon0x40
ID: 36971653
I will open another question for more troubleshooting on the VOIP. it seems like everyone is in agreement that the RTT do not look excessive?

inbox788 If I understand what you are asking then VOIP analysis tools show packets that did not make it in time to be placed into the voice stream. (They are not dropped physically just too late) Most protocols don't care if there are delays, jitter and out of sequence packets but VOIP can't use delayed packets.

The 3750 we have is a switchstack of 3 switches and the processor shows spikes up to 90% utlization and just seems like it might be the weak link. The average cpu utilization is about 25%.
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by:inbox788
ID: 36971899
I'm not clear on whether you're having a current problem that you're trying to solve. Are the VOIP phones up and running? Is there an issue with call quality or are you still planning/building it? Do you have end-to-end bandwidth, latency, jitter and packet loss test results?

You could do test from both ends to a 3rd party and see how things work. Of course, any trouble-spots may not immediately mean your setup is responsible.

http://www.whichvoip.com/voip/speed_test/ppspeed.html

High CPU utilization in a router can be a source of additional latency/delay, so while it's still under 100% now, at higher loads, it may become problematic. You might be able to shut down CPU intensive features if they're not crucial or have to upgrade the box.
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